JP2011116904A - Method for producing composite particle, composite particle, resin composition, wavelength conversion layer, and photovoltaic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing composite particles excellent in light-emitting properties (emission quantum yield) and excellent in dispersibility and durability over a long period of time. <P>SOLUTION: The composite particles include semiconductor particles of zinc oxide and particles of an inorganic compound. The method for producing the composite particles includes at least one step of subjecting an intermediate of the composite particles to reduction treatment in the production process of the composite particles. The step of subjecting the composite particles to reduction treatment includes subjecting the intermediate of the composite particles to heat treatment in an atmosphere containing a gas having reduction ability, when a dispersion of the semiconductor particles is mixed with a dispersion of the particles of an inorganic compound and the resulting mixed dispersion is dried by a spray drying process. For example, when the intermediate of the composite particles is spray-dried with a spray dryer 100, a method of using hydrogen gas as a carrier gas is preferred. The resin composition containing the composite particles produced by the method for producing composite particles is used for a wavelength conversion layer and a photovoltaic device, which have high-performance and are excellent in reliability. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing composite particles, composite particles, a resin composition, a wavelength conversion layer, and a photovoltaic device.

  Photovoltaic devices are used as solar cells that photoelectrically convert sunlight to extract electrical energy. As this type of photovoltaic device, currently, one using single crystal silicon, polycrystalline silicon, spherical silicon, amorphous silicon, CdTe, or CIGS as a photovoltaic layer for converting light into electromotive force is mainly used. Recently, organic solar cells such as dye-sensitized solar cells have been developed, and various photovoltaic layers containing organic materials have been used.

  In the case of these photovoltaic devices, since the spectral sensitivity is limited to the substantially visible light region, it is possible to efficiently convert regions other than visible light, such as the ultraviolet region and the infrared region, into sunlight. Can not. In addition, the crystalline silicon solar cell has a problem in that the photoelectric conversion efficiency is lowered as the temperature rises due to ultraviolet light absorption. Furthermore, in an organic solar cell using a photovoltaic layer containing an organic material, there has been a problem that the photoelectric conversion efficiency is lowered as the organic material is deteriorated by ultraviolet rays.

  Here, Patent Document 1 uses a quantum dot composed of semiconductor fine particles such as CdSe, CdTe, GaN, Si, InP, and ZnO, and particles (core-shell particles) obtained by making them into a core-shell type, as a wavelength conversion substance. Proposed. By using such quantum dots, light in a wavelength region that cannot be used for photoelectric conversion is converted into light in a wavelength region that can be photoelectrically converted, and an energy conversion film that can increase the photoelectric conversion efficiency of a solar cell is obtained. .

  However, the quantum dots described in Patent Document 1 have low light emission characteristics and have not sufficiently increased the photoelectric conversion efficiency of solar cells.

JP 2006-216560 A

  An object of the present invention is to produce a composite particle capable of efficiently producing composite particles having excellent luminescent properties (luminescence quantum yield) and excellent long-term dispersibility and durability, and a method for producing such composite particles. And providing a resin composition having the composite particles.

  It is another object of the present invention to provide a wavelength conversion layer and a photovoltaic device that have high performance and excellent reliability.

Such an object is achieved by the present inventions (1) to (28) below.
(1) A method for producing composite particles comprising zinc oxide semiconductor particles and inorganic compound particles,
A method for producing composite particles, comprising a step of reducing the intermediate of the composite particles at least once during the step of producing the composite particles.

  (2) The reduction treatment includes heating the intermediate of the composite particles in a reducing atmosphere composed of a gas having a reducing ability and a mixed gas of a gas having a reducing ability and an inert gas. The method for producing composite particles according to (1) above, which is to be treated.

  (3) The method for producing composite particles according to (2), wherein the gas having the reducing ability is hydrogen gas.

  (4) The method for producing composite particles according to (2) or (3) above, wherein the content of the gas having the reducing ability in the mixed gas is 1 to 10% by volume or 85 to 100% by volume.

(5) The intermediate of the composite particles includes particles having a reducing ability,
The method for producing composite particles according to the above (1), wherein the reduction treatment includes heat-treating the intermediate of the composite particles.

  (6) The method for producing composite particles according to (5), wherein the particles having the reducing ability are carbon particles.

  (7) In the above-mentioned step (1), the step of reducing treatment is to coexist the intermediate of the composite particles and a simple substance or alloy of reducing metal in the same space, and heat-treat them. A method for producing the composite particles according to 1.

  (8) The reduction treatment step includes heat-treating the pipe in a state where at least the inner surface is provided with the composite particle intermediate body in the pipe made of the metal having a reducing ability or an alloy. The manufacturing method of the composite particle as described in said (7) which is what.

  (9) The method for producing composite particles according to (7) or (8), wherein the metal having reducing ability is copper.

  (10) The method for producing composite particles according to any one of (1) to (9), wherein the reduction treatment step is performed at 200 to 1,000 ° C.

  (11) The method for producing composite particles according to any one of (1) to (10), wherein the step of reducing treatment is performed while the step of combining the semiconductor particles and the inorganic compound particles is performed.

  (12) The method for producing composite particles according to any one of (1) to (10), wherein the step of reducing treatment is performed after the step of combining the semiconductor particles and the inorganic compound particles.

  (13) The method for producing composite particles according to (11) or (12), wherein the step of combining is performed by a spray drying apparatus.

  (14) The method for producing composite particles according to any one of (1) to (13), wherein an average particle size of primary particles of the semiconductor particles is 1 to 10 nm.

  (15) The method for producing composite particles according to any one of (1) to (14), wherein the inorganic compound particles are oxide particles.

(16) The method for producing composite particles according to (15), wherein the inorganic compound particles are at least one of silica (SiO ₂ ) particles and zirconia (ZrO ₂ ) particles.

  (17) The method for producing composite particles according to any one of (1) to (16), wherein the content of the semiconductor particles is 10 to 90% by volume of the entire composite particles.

  (18) A composite particle obtained by the method for producing a composite particle according to any one of (1) to (17).

  (19) A resin composition comprising the composite particles according to (18) above and a curable resin.

  (20) The resin composition according to (19), wherein the content of the composite particles is 30 to 70% by volume of the entire resin composition.

  (21) A wavelength conversion layer obtained by curing a layer composed of the resin composition according to (19) or (20).

  (22) A photovoltaic device comprising the wavelength conversion layer according to (21).

  (23) The photovoltaic device according to (22), wherein the wavelength conversion layer has an uneven structure in a plane thereof.

  (24) The photovoltaic device according to (23), wherein the uneven structure has a height difference of 300 nm to 100 μm.

  (25) The photovoltaic device according to (23) or (24), wherein an in-plane period of the concavo-convex structure is 300 nm to 50 μm.

  (26) The photovoltaic device according to any one of (23) to (25), wherein the uneven structure has a fine uneven shape smaller than the uneven structure.

(27) It has a laminate formed by laminating two or more wavelength conversion layers,
The photovoltaic device according to any one of (23) to (26), wherein a shape of the uneven structure is different between the two wavelength conversion layers.

  (28) The light according to any one of (22) to (27), wherein the wavelength conversion layer is formed by supplying the resin composition by an inkjet method and curing the supplied resin composition. Electromotive device.

  ADVANTAGE OF THE INVENTION According to this invention, the composite particle which was excellent in the light emission characteristic (luminescence quantum yield) of composite particle, and was excellent in the dispersibility and durability over a long period of time can be manufactured efficiently. Moreover, the resin composition which has the composite particle excellent in the luminescent property is obtained.

  Further, according to the present invention, by using the resin composition, a wavelength conversion layer and a photovoltaic device excellent in performance and reliability can be obtained.

It is sectional drawing which shows typically 1st Embodiment of the photovoltaic apparatus of this invention provided with the wavelength conversion layer of this invention containing the composite particle of this invention. It is sectional drawing which shows typically embodiment of the wavelength conversion layer of this invention containing the composite particle of this invention. It is the schematic which shows an example of the spray-drying apparatus used for 1st Embodiment of the manufacturing method of the composite particle of this invention. It is sectional drawing which shows typically 2nd Embodiment of the photovoltaic apparatus of this invention. It is sectional drawing which shows typically 3rd Embodiment of the photovoltaic apparatus of this invention. It is sectional drawing and the top view which show typically 4th Embodiment of the photovoltaic apparatus of this invention. It is sectional drawing and the top view which show typically 4th Embodiment of the photovoltaic apparatus of this invention. It is sectional drawing and the top view which show typically 4th Embodiment of the photovoltaic apparatus of this invention. It is sectional drawing and the top view which show typically 4th Embodiment of the photovoltaic apparatus of this invention. It is sectional drawing and the top view which show typically 4th Embodiment of the photovoltaic apparatus of this invention. It is sectional drawing and the top view which show typically 4th Embodiment of the photovoltaic apparatus of this invention.

  Hereinafter, the method for producing composite particles, composite particles, resin composition, wavelength conversion layer and photovoltaic device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

(Composite particles)
First, the composite particles of the present invention will be described.

  FIG. 1 is a cross-sectional view schematically showing a first embodiment of the photovoltaic device of the present invention including the wavelength conversion layer of the present invention including the composite particles of the present invention, and FIG. 2 includes the composite particles of the present invention. It is sectional drawing which shows typically embodiment of the wavelength conversion layer of this invention.

  The composite particles of the present invention are particles containing zinc oxide semiconductor particles and inorganic compound particles.

  Since such composite particles have a function of changing the emission wavelength with respect to the absorption light wavelength, they are particularly used as a wavelength conversion material. A photovoltaic device 1 (photovoltaic device of the present invention) 1 shown in FIG. 1 is applied to, for example, a solar cell, etc., and includes a photovoltaic layer 2 that generates an electromotive force with light irradiation, and a photovoltaic device. It has the wavelength conversion layer (wavelength conversion layer of the present invention) 3 provided on the light incident surface side of the layer 2 and containing the composite particles of the present invention. The wavelength conversion layer 3 can convert light (electromagnetic waves) in a wavelength region unsuitable for photoelectric conversion into light in a wavelength region capable of photoelectric conversion, and can improve the photoelectric conversion efficiency of the photovoltaic device 1.

  The wavelength conversion layer 3 shown in FIG. 2 is obtained by dispersing composite particles 4 (composite particles of the present invention) in a curable resin 5.

  The composite particles 4 shown in FIG. 2 include semiconductor particles 6 and inorganic compound particles 8, but the distribution form of these particles 6 and 8 is not particularly limited. An example of a preferable distribution form is (a) a form in which the semiconductor particles 6 are covered with inorganic compound particles 8 (see FIG. 2A). Since the semiconductor particles 6 have high activity, the durability of the curable resin 5 is reduced. However, since the inorganic compound particles 8 are disposed so as to cover the semiconductor particles 6, the activity of the semiconductor particles 6 is increased. As a result, the durability of the curable resin 5 can be further increased. As a result, the wavelength conversion layer 3 using the composite particles 4 of the present invention is highly durable.

  More specifically, this form is a form in which the semiconductor particles 6 and the inorganic compound particles 8 are aggregated (adsorbed) to each other, and are classified into several forms based on the aggregation pattern.

  As the form of the composite particles 4 classified based on the aggregation pattern of the particles 6 and 8, for example, (b-1) a form in which the semiconductor particles 6 and the inorganic compound particles 8 are randomly distributed (FIG. 2). (See (b-1)), (b-2) a form in which the semiconductor particles 6 are connected in a chain shape, and the gaps are filled with inorganic compound particles 8 (see FIG. 2 (b-2)), ( b-3) The form (refer FIG.2 (b-3)) etc. with which the particle | grains 8 of an inorganic compound are arrange | positioned so that the circumference | surroundings of the semiconductor particle 6 may be mentioned. In FIG. 2, the small circles indicate the semiconductor particles 6, and the large circles indicate the inorganic compound particles 8.

  Among these, the form of (b-2) and the form of (b-3) are preferable, and the form of (b-2) is more preferable. The composite particles 4 having these forms are connected (aggregated) with a plurality of semiconductor particles 6 so that excellent emission characteristics (especially, an excitation absorption band can be expanded). And a characteristic of shifting to the long wavelength side. And the said form is useful from a viewpoint that the said effect is acquired even if it does not increase the addition amount of the semiconductor particle 6 very much. Particularly in the case of (b-2), the semiconductor particles 6 linked in a chain form have excellent light emission characteristics equivalent to particularly large semiconductor particles with a particularly small addition amount, so that a great effect is obtained.

  In addition, in such a form, the cross section of the composite particle 4 is scanned with various electron microscopes such as a scanning electron microscope (SEM) and a transmission electron microscope (TEM, FE-TEM), an atomic force microscope (AFM), and scanning. It can be confirmed and evaluated by observing with a scanning tunneling microscope (STM), a three-dimensional atom probe device (3D-AP), an energy dispersive X-ray analyzer (EDX) or the like. Moreover, the cross section of the composite particle 4 can be produced by, for example, a focused ion beam processing observation apparatus (FIB) or the like.

  Further, when the semiconductor particles 6 are covered with the inorganic compound particles 8, it is not necessary that the semiconductor particles 6 are completely covered with the inorganic compound particles 8, and a portion that is not partially covered is provided. There may be.

  Furthermore, the inorganic compound particles 8 may be arranged so as to cover not only the single semiconductor particle 6 but also the aggregate of the plurality of semiconductor particles 6, and in this case, the inorganic compound particles 8. The number of is not particularly limited.

  As described above, since the semiconductor particles 6 and the inorganic compound particles 8 are composited, the composite particles 4 of the present invention control the activity of the semiconductor particles 6 and prevent aggregation of the semiconductor particles 6. Thus, the semiconductor particles 6 can be uniformly dispersed in the dispersion medium. For this reason, the absorption and emission characteristics are improved, and it can be used as a high-performance wavelength conversion material.

Hereinafter, semiconductor particles and inorganic compound particles will be sequentially described.
The semiconductor particles used in the present invention are composed of zinc oxide (ZnO) particles. Zinc oxide is useful from the viewpoint of production cost and ease of work for producing composite particles because it has little risk of resource depletion and low toxicity.

  As the semiconductor particles, those containing rare earth elements are preferably used. By adding a rare earth element to the semiconductor particles, the composite particles can control the absorption characteristics such as the absorption wavelength and the emission characteristics such as the emission wavelength. Thereby, for example, ultraviolet rays, infrared rays and the like that are not used for photoelectric conversion can be converted into light having a wavelength capable of photoelectric conversion, so that a wavelength conversion material capable of realizing a solar cell with higher photoelectric conversion efficiency can be obtained.

  As the rare earth elements contained in the semiconductor particles, 17 elements consisting of lanthanoid elements having atomic numbers 57 to 71 and scandium (Sc) and yttrium (Y) can be used alone or in combination of two or more. However, a combination of one or more of europium (Eu), erbium (Er), thulium (Tm) and ytterbium (Yb) is particularly preferable.

  Among these, by including europium (Eu) as a rare earth element in particular, the composite particles have a wavelength conversion function of absorbing ultraviolet light and emitting visible light.

  In particular, the composite particles include one of erbium (Er), thulium (Tm) and ytterbium (Yb) as rare earth elements, so that the composite particles absorb ultraviolet rays and emit infrared rays, or absorb infrared rays. In addition, it has a wavelength conversion function for emitting visible light.

  Note that the above-described zinc oxide can be doped with rare earth elements without using a large-scale apparatus such as a vacuum apparatus. For this reason, by using zinc oxide particles as the semiconductor particles, it is possible to uniformly and efficiently dope rare earth elements to a plurality of semiconductor particles, and as a result, obtain composite particles having excellent absorption and emission characteristics. Can do.

  The content of the rare earth element in the entire composite particle is preferably 0.01 to 20% by weight, and more preferably 0.02 to 10% by weight. By setting the content of the rare earth element within the above range, composite particles excellent in absorption and emission characteristics such as emission quantum yield can be obtained.

  Such semiconductor particles preferably have an average primary particle diameter of 1 to 10 nm, more preferably 1 to 5 nm. By setting the average particle size within the above range, the quantum size effect appears more remarkably in the semiconductor particles, and thus the absorption / emission characteristics of the semiconductor particles are particularly improved. As a result, a wavelength conversion material capable of realizing a photovoltaic device with higher photoelectric conversion efficiency is obtained. In addition, by setting the average particle diameter within the above range, the semiconductor particles are smaller than the wavelength of visible light, so the influence of the semiconductor particles on the transmitted light is reduced, and the transparency of the semiconductor particle dispersion is improved. To do.

  The average particle size of the primary particles of the semiconductor particles is evaluated in the state of a transparent dispersion formed by dispersing the semiconductor particles in a dispersion medium using, for example, a dynamic light scattering device (Zetasizer Nano ZS manufactured by Malvern). can do.

  Further, the content of the semiconductor particles in the whole composite particle is preferably 10 to 90% by volume, more preferably 30 to 80% by volume, and further preferably 50 to 80% by volume. By setting the content of the semiconductor particles within the above range, the absorption and emission characteristics of the semiconductor particles can be enhanced, and the durability of the semiconductor particles can be enhanced.

  In addition, when content of a semiconductor particle is less than the said lower limit, there exists a possibility that the wavelength conversion function by a semiconductor particle may fall in a composite particle. On the other hand, when the content of the semiconductor particles exceeds the upper limit, the semiconductor particles and the inorganic compound particles are not uniformly dispersed, and the action of the inorganic compound particles such as controlling the activity of the semiconductor particles is reduced. Therefore, the stability and durability of the composite particles may be reduced.

  Examples of the inorganic compound particles used in the present invention include particles having a composition different from that of the semiconductor particles. Examples thereof include particles of various metals, non-metal nitrides, oxides, phosphides, sulfides, and the like. However, oxide particles are particularly preferably used. By using oxide particles as the inorganic compound particles, the chemical stability of the composite particles, particularly in the atmosphere, can be improved, and durability over a long period of time can be improved.

Here, specific examples of the inorganic compound particles include at least one selected from the group consisting of ZnO, SiO ₂ , ZnS, GaN, CdS, GaP, CdS, ZrO ₂ , YVO ₄ , and Y ₂ O ₃ . Particles are preferably used, and at least one of silica (SiO ₂ ) particles and zirconia (ZrO ₂ ) particles is more preferably used. Since these oxides are particularly excellent in chemical stability, the activity of the semiconductor particles can be controlled and the durability of the resin composition can be reliably increased. As a result, absorption / emission characteristics such as emission quantum yield in the composite particles can be enhanced.

  The average particle size of the primary particles of such inorganic compound particles is not particularly limited, but is preferably about 1.5 to 10 times the average particle size of the primary particles of the semiconductor particles, and about 2 to 8 times. More preferably. By setting the average particle size of the inorganic compound particles within the above range, the packing properties of the semiconductor particles and the inorganic compound particles are improved, so that denser composite particles can be obtained.

  The inorganic compound particles used in the present invention may be produced by any method, and any known method may be used. Common production methods include, for example, spray drying method, flame spray method, plasma method, gas phase reaction method, freeze drying method, precipitation method (coprecipitation method), hydrolysis method (salt aqueous solution method, alkoxide method, sol-gel) Method), hydrothermal method (precipitation method, crystallization method, hydrothermal decomposition method, hydrothermal oxidation method, etc.).

  In the composite particles of the present invention, the lithium content is preferably 3% by weight or less, more preferably 2% by weight or less, and even more preferably 1% by weight or less, thereby improving dispersibility and durability with respect to the dispersion medium. Can solve the problem. Although the reason for this is not clarified in detail, it is considered that lithium inhibits adsorption (aggregation) between semiconductor particles and inorganic compound particles by adsorbing moisture in the atmosphere.

  In other words, lithium is distributed in the composite fine particles and hinders smooth adsorption (aggregation) between the semiconductor particles and the inorganic compound particles, so that the composite particles are not likely to have a spherical particle shape and are likely to have an irregular shape. Furthermore, when it becomes an irregular shape, the semiconductor particles are likely to be exposed, so that the activity of the exposed semiconductor particles cannot be controlled. As a result, it is considered that the light resistance and long-term stability of the resin composition are lowered.

  On the other hand, according to the present invention, the above-described problems can be reliably solved by controlling the lithium content within the above range. Further, by setting the lithium content within the above range, the emission quantum yield can be increased.

  Examples of the method of bringing the lithium content into the above range include a method of subjecting semiconductor particles or composite particles to a washing treatment, a method of passing a dispersion of semiconductor particles through an ion exchange resin (permeable membrane), and the like.

  Moreover, even if it uses the manufacturing method (for example, zinc oxide synthesis method etc.) of the semiconductor particle which does not use lithium in a raw material, lithium content can be made into the said range.

  On the other hand, if the lithium content is less than or equal to the above upper limit, the effects as described above can be obtained, but preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and further preferably 0.5% by weight. A lower limit value of% or more may be set. By making lithium content more than this lower limit, said subject can be solved more reliably. Although the effect of solving the above-mentioned problem becomes conspicuous as the lithium content decreases, there is a maximum value in the magnitude of the effect, and this maximum value contains lithium from the lower limit. This is because it is located in a region having a large amount. That is, when the lithium content is less than the lower limit, the light emission characteristics may be deteriorated.

  In the present invention, the acetic acid content in the composite particles is preferably 20% by weight or less, more preferably 10% by weight or less, still more preferably 9% by weight or less, and 8% by weight. Most preferably: By setting the content of acetic acid within the above range, heat resistance and weather resistance are improved.

  For acetic acid, a lower limit of preferably 0.01% by weight or more, more preferably 0.1% by weight or more may be set. By setting the acetic acid content to be equal to or higher than this lower limit, the above-mentioned problems can be solved more reliably and the emission quantum yield can be increased.

  Furthermore, in the present invention, the total content of other ionic impurities in the composite particles is preferably 0.5% by weight or less, and more preferably 0.3% by weight or less. Since these ionic impurities also affect the characteristics of the composite particles, the effect of the present invention becomes more remarkable by reducing the content thereof.

Other ionic impurities include, for example, F ⁻ , Cl ⁻ , NO ₂ ⁻ , Br ⁻ , NO ₃ ⁻ , PO ₄ ³⁻ , SO ₄ ²⁻ , (COO) ₂ ²⁻ , HCOO ⁻ , Na ⁺ , NH ₄ ⁺ , K ⁺ , Mg ²⁺ , Ca ^{2+ and the} like.

  Such contents of lithium, acetic acid, and ionic impurities can be measured by, for example, ion chromatography analysis. In the case of lithium chromatographic analysis, the above-described lithium content and acetic acid content are measured as lithium ion content and acetate ion content, respectively.

  The ion chromatographic analysis is performed by the following procedure, for example, using ion chromatography.

  First, a sample to be analyzed is placed in a container and diluted with ultrapure water. Then, after sealing the container, the container is put into a thermostatic chamber, and the container is subjected to hot water treatment at, for example, 125 ° C. × 20 hours.

  Next, the container subjected to the hot water treatment is gradually cooled to room temperature. Then, the sample in the container is subjected to a centrifugal separation process and a filter filtration process, and the sample after each process is used as a test solution for ion chromatography analysis.

  Subsequently, the obtained test solution and an ion standard sample having a known concentration are introduced into ion chromatography, and the content of each ion in the test solution is quantified by a calibration curve method.

  As described above, the lithium content, the acetic acid content, and the content of other ionic impurities can be measured.

  The composite particles of the present invention preferably satisfy the following conditions in thermogravimetric analysis.

  For example, the composite particles are subjected to thermogravimetric analysis for measuring the weight loss (reduction rate) between 250 and 500 ° C. when the temperature is raised from room temperature at 10 ° C./min.

  In the composite particles of the present invention, the weight loss measured by thermogravimetric analysis is preferably 20% or less, and more preferably 15% or less. Such a composite particle indicates that the content of a substance to be measured for weight loss in thermogravimetric analysis, in particular, the content of organic impurities, is very small, and can solve the above problems more reliably. It becomes. In addition, the emission quantum yield is higher.

  The average particle size of the composite particles of the present invention is not particularly limited, but is preferably 20 to 100 nm, more preferably 45 to 55 nm. When the average particle size is within the above range, the dispersibility in the dispersion medium is particularly improved, and the composite particles can be filled in the dispersion medium at a high density. Thereby, the light emission characteristics of the composite particle dispersion are improved, and a transparent dispersion (for example, a resin composition described later) in the visible light region is obtained.

  The average particle size of the composite particles can also be evaluated in the state of a transparent dispersion using, for example, a dynamic light scattering device (Malvern, Zetasizer Nano ZS).

  As described above, the composite particles as described above have high absorption / emission characteristics and are used as a high-performance wavelength conversion material. For this reason, it can use for optical materials with which various devices, such as EL illumination, optical communication, EL display body, LED illumination, a solar cell, bioimaging, are provided, for example. In particular, it is preferably used as a wavelength conversion material provided in LED lighting, solar cells and the like.

  Further, when used in the above-described applications, the emission quantum yield of the composite particles of the present invention is preferably 30% or more at the excitation wavelength in the visible light region or near ultraviolet region, and preferably 40% or more. It is more preferable that

Next, the manufacturing method of the composite particle of this invention is demonstrated.
(Method for producing composite particles)

<First Embodiment>
First, 1st Embodiment of the manufacturing method of the composite particle of this invention is described.

[1] Manufacture of Semiconductor Particles Prior to the description of the method of manufacturing composite particles, first, the method of manufacturing semiconductor particles will be described. Examples of the method for producing semiconductor particles include various liquid phase methods such as a sol-gel method, a solvothermal method (including a hydrothermal synthesis method), and a synthesis method using zinc nitrate, a flame method, and a sputtering method. Examples include various gas phase methods.

Here, the sol-gel method will be described as an example.
First, zinc acetate or a hydrate thereof (for example, zinc acetate dihydrate) is prepared as a raw material and dissolved in a solvent. Examples of the solvent include ethanol and propanol.

  Next, the solution is refluxed as necessary. The heating temperature in the reflux treatment is appropriately set according to the volatility of the solvent and the reaction temperature of the solute, but is preferably about 60 to 100 ° C., and the duration of the reflux treatment is about 30 minutes to 10 hours. It is said.

  Next, an alkali metal hydroxide is added to the obtained solution, and the mixture is allowed to stand at a low temperature (eg, 10 ° C. or lower). Thereby, the dispersion liquid of a zinc oxide semiconductor particle is obtained. Examples of the alkali metal include lithium and sodium.

When producing semiconductor particles doped with rare earth elements, in addition to zinc acetate or hydrates thereof, acetates of rare earth elements or hydrates thereof (for example, erbium acetate tetrahydrate, europium acetate tetrahydrate) Etc.) may be added.
Semiconductor particles can be manufactured as described above.

  The obtained dispersion of semiconductor particles is preferably subjected to a washing treatment. As a result, various impurities such as lithium, acetic acid, ionic impurities, and organic impurities attached to the semiconductor particles can be removed.

  Examples of the cleaning treatment include a method of adding a cleaning liquid to a dispersion of semiconductor particles. You may add a vibration, an ultrasonic wave, etc. to a washing | cleaning liquid as needed.

  Examples of the cleaning liquid include hexane, pentane, heptane, octane, cyclohexane, and acetone.

  Of these, hexane is particularly preferably used for the cleaning liquid. Since hexane has a relatively low polarity, the polarity of the dispersion liquid of semiconductor particles can be greatly changed. As a result, the effect of improving the separation performance between the semiconductor particles, the ionic impurities, and the organic impurities, that is, the efficiency of the cleaning process can be obtained.

  As a method for removing various impurities such as lithium, acetic acid, ionic impurities and organic impurities adhering to the semiconductor particles, in addition to the above-described cleaning treatment, (i) Examples include a method of performing the same cleaning treatment, and (ii) a method of passing a dispersion of semiconductor particles through an ion exchange resin (permeable membrane).

  Furthermore, composite particles having a low lithium content can be produced by using a method for producing semiconductor particles that does not use lithium (for example, a zinc oxide synthesis method).

The addition amount of the cleaning liquid is preferably about 1 to 10 by volume ratio, more preferably about 2 to 5 when the volume of the semiconductor particles is 1. When the addition amount of the cleaning liquid falls below the lower limit, the above-described cleaning effect is impaired. On the other hand, when the addition amount of the cleaning liquid exceeds the upper limit, no further improvement in the cleaning liquid effect can be expected.
In addition, the frequency | count of a washing process is not specifically limited, Multiple times may be sufficient.

[2] Manufacture of Composite Particles Next, a method for manufacturing composite particles will be described. The composite particles of the present invention may be produced by any method. For example, a dispersion of semiconductor particles and a dispersion of inorganic compound particles are mixed, and the mixture is finely divided by various atomization methods. A spray-drying method in which droplets are formed and dried is preferably used.

  Hereinafter, a method of mixing a dispersion of semiconductor particles and a dispersion of inorganic compound particles and drying the mixed dispersion by a spray drying method will be described in detail.

  This method includes: [2-1] a mixing step of mixing a dispersion of semiconductor particles and a dispersion of inorganic compound particles; and [2-2] a compounding step of combining semiconductor particles and inorganic compound particles. And have. Hereinafter, each process is explained in full detail.

[2-1] Mixing Step First, a dispersion of semiconductor particles and a dispersion of inorganic compound particles are prepared.

  The semiconductor particle dispersion is obtained by dispersing the semiconductor particles produced by the method [1] in a dispersion medium. Examples of the dispersion medium include ethanol and propanol.

  The concentration of the semiconductor particle dispersion is not particularly limited, but is preferably about 0.01 to 5M, more preferably about 0.05 to 1M.

  On the other hand, a dispersion of inorganic compound particles is also obtained by dispersing inorganic compound particles in a dispersion medium as described above.

  The concentration of the dispersion of inorganic compound particles is not particularly limited, but is preferably about 0.01 to 5M, and more preferably about 0.05 to 1M.

  Next, the semiconductor particle dispersion and the inorganic compound particle dispersion are mixed to prepare a mixed dispersion (intermediate of composite particles).

[2-2] Compositing Step Next, the obtained mixed dispersion (intermediate of composite particles) is dried while being powdered. Thereby, composite particles are obtained.

  As the drying method, any drying method such as a flame drying method or a reduced pressure drying method can be used, but a spray drying method is particularly preferably used. According to the spray drying method, homogeneous composite particles having a uniform particle diameter can be efficiently produced. In addition, since the powder is dried while being pulverized into fine particles, a significantly high temperature is not required. For this reason, it is also possible to use a raw material with low heat resistance.

  FIG. 3 is a schematic view showing an example of a spray drying apparatus used in the first embodiment of the method for producing composite particles of the present invention.

  A spray drying apparatus 100 shown in FIG. 3 includes a sprayer 110, an electric furnace 120 including a furnace core tube 121 and a heater 122, and a bag filter 130.

  The sprayer 110 atomizes the slurry-like raw material into droplets and sprays with high-pressure gas.

  As the various atomization methods, any method can be used as long as the mixed dispersion is made into fine droplets, but an atomization method using an ultrasonic atomizer or a two-fluid nozzle is preferably used. An ultrasonic atomizer is preferably used. The ultrasonic atomizer can produce droplets having a size of several microns without heating the mixed dispersion. As a result, the mixed dispersion can be atomized without degrading the semiconductor particles by heat. Moreover, it is preferable that the droplets produced by various atomization methods are separated into smaller sized droplets by a classifier such as a cyclone. By using the classification device, uniform composite fine particles having a particle diameter of several tens of nanometers or less can be finally produced.

  Any method may be used for drying the droplets as long as the solvent in the droplets can be dried. In addition to the method of passing through a heated furnace as described here, a method of irradiating a laser or microwave Etc. are used.

  Further, the furnace core tube 121 provided in the electric furnace 120 has a cylindrical shape elongated in the vertical direction, and a heater 122 is provided so as to cover the outer peripheral surface thereof. The inside of the core tube 121 can be heated by the heater 122.

  The lower end of the core tube 121 and the sprayer 110 are connected by a pipe 140, and raw material droplets sprayed from the sprayer 110 are supplied into the core tube 121. The raw material sprayed in the core tube 121 is dried by heating to become a solid powder.

  On the other hand, the upper end of the core tube 121 and the bag filter 130 are connected by a pipe 150. The solid powder generated by drying is sent to the bag filter 130 via the pipe 150, and the bag filter 130 collects the powder. The gas carrying the powder is sent from the bag filter 130 to an exhaust gas device (not shown).

  Then, the procedure which manufactures composite particle | grains using said spray-drying apparatus 100 is demonstrated.

First, the mixed dispersion prepared in [2-1] and the high-pressure gas are supplied to the nebulizer 110.
Next, the mixed dispersion is atomized into fine droplets by various atomization methods and sprayed into the core tube 121 using a high-pressure gas.

  In the core tube 121, the droplets are dried by the influence of heat, and the semiconductor particles and the inorganic compound particles contained in the droplets are adsorbed to each other. As a result, composite particles containing semiconductor particles and inorganic compound particles are obtained. As described above, according to the spray drying apparatus 100, it is possible to efficiently produce fine and uniform composite particles containing two kinds of particles, and spontaneously become spherical droplets due to surface tension. It becomes possible to produce spherical composite particles.

  Here, the present invention is characterized in that the mixed dispersion liquid (intermediate of composite particles) is subjected to a reduction treatment at least once in the production process of such composite particles.

  The reduction treatment may be any treatment as long as it is a treatment that reduces the zinc oxide constituting the semiconductor particles in the mixed dispersion, but here, a detailed description is given of a method of performing the reduction treatment while performing spray drying. Describe.

  Here, the high-pressure gas (carrier gas) supplied to the nebulizer 110 includes a gas having a reducing ability for semiconductor particles.

  Examples of the gas having such reducing ability (reducing gas) include hydrogen and carbon monoxide. Among these, hydrogen is preferably used from the viewpoints of reduction ability, safety, and the like.

  The high-pressure gas may be a mixed gas containing these reducing gas and inert gas. Examples of the inert gas include nitrogen, helium, argon, and the like.

  Although the content rate of the reducing gas in the mixed gas is not particularly limited as long as the reducing gas is contained, it is preferably 1 to 10% by volume, more preferably 3 to 8% by volume. . Such a mixed gas has a necessary and sufficient reducing ability and can prevent excessive reduction treatment.

  Or it is preferable that it is 85-100 volume%, and it is more preferable that it is 90-100 volume%. Since such a mixed gas has a high hydrogen concentration, the reducing ability is large, and the reduction treatment can be performed in a shorter time than when a mixed gas having a low hydrogen concentration is used.

  When a reducing gas is used as the high-pressure gas, composite particles are formed in the electric furnace 120 and a reducing action acts on the semiconductor particles. This reduction action partially reduces zinc oxide in the semiconductor particles.

  By the way, the composite particles of the present invention are applied to various uses by utilizing the light emission characteristics of zinc oxide.

  The light emission mechanism of zinc oxide is considered to be caused by various point defects existing in the crystal lattice of zinc oxide. One of these point defects is an oxygen defect. In order to increase the light emission characteristics, particularly the light emission quantum yield, of the semiconductor particles of zinc oxide, it is necessary to control so as to include this oxygen defect.

  As described above, in the present invention, since zinc oxide in the semiconductor particles is partially reduced during the manufacturing process of the composite particles, oxygen defects are thereby formed in the zinc oxide. As a result, the light emission characteristics (luminescence quantum yield) in the semiconductor particles can be enhanced. Therefore, the composite particles containing such semiconductor particles are excellent in light emission characteristics and excellent in dispersibility and durability as described above.

  Further, by performing the reduction treatment while forming the composite particles, the reducing action acts on the semiconductor particles before the composite particles are completely formed. When the composite particles are completely formed, the semiconductor particles and the inorganic compound particles are adsorbed to each other, so there is a possibility that the semiconductor particles and the reducing gas cannot be sufficiently reduced. If particles are in the process of being formed, the reducing gas can be contacted with the semiconductor particles more frequently, so that the reduction treatment can be sufficiently performed.

  The temperature in the reduction treatment (temperature in the core tube 121) is preferably 200 to 1000 ° C, more preferably 300 to 950 ° C, and further preferably about 500 to 900 ° C. Thereby, it is possible to reliably perform the drying process and the reduction process on the droplet moving at high speed. In addition, when temperature is less than the said lower limit, there exists a possibility that a drying process and a reduction process may become inadequate. On the other hand, when temperature exceeds the said upper limit, a reduction process will become excess and zinc oxide more than necessary will be reduce | restored. As a result, the semiconductor particles may lose semiconductor characteristics.

Further, the reduction process is not limited to once, and may be performed a plurality of times. Further, after the reduction treatment is performed while forming the composite particles, the reduction treatment may be performed separately.
As described above, composite particles having excellent light emission characteristics can be obtained.

  Note that when forming the composite particles, the reduction treatment may not be performed, and the reduction treatment may be performed separately after the composite particles are manufactured. In this case, since there is no limitation on the time for performing the reduction treatment, sufficient reduction treatment can be performed over time while taking into consideration the light emission characteristics of the composite particles. Therefore, even if the composite particles are completely formed, there is no problem with the reduction treatment. In this case, the high-pressure gas supplied into the core tube 121 may not include a gas having a reducing ability, and may be an inert gas or an oxidizing gas such as air or oxygen. Good.

  Moreover, when performing a reduction process separately, it can carry out using a continuous type and a batch type heating furnace.

  In this case, the heating temperature is preferably equivalent to the above temperature range, and the heating time is preferably about 5 minutes to 5 hours.

Moreover, you may make it use the composite particle after manufacture for a grinding | pulverization process as needed. Examples of the pulverization method include a method using various pulverizers such as a ball mill and a bead mill, and various dispersers such as an ultrasonic dispersion apparatus.
Furthermore, classification processing may be performed as necessary.

  In addition, the composite particle manufactured with the reduction process contains more oxygen defects than before the process. The presence or absence of an increase in the amount of oxygen defects can be evaluated by, for example, laser Raman spectroscopy.

Second Embodiment
Next, a second embodiment of the method for producing composite particles of the present invention will be described.

  Hereinafter, although the second embodiment will be described, the description will focus on the differences from the first embodiment, and the description of the same matters will be omitted.

  This embodiment is the same as the first embodiment except that instead of using a gas having reducing ability, a mixed dispersion liquid (intermediate of composite particles) containing particles having reducing ability is used.

  First, in the mixing step, particles having reducing ability are added to a mixed dispersion liquid (intermediate of composite particles) containing semiconductor particles and inorganic compound particles.

  Examples of the particles having a reducing ability include carbon particles such as carbon black and graphite powder, or particles containing a carbon material, and carbon particles are preferably used. Carbon particles are suitable as particles having reducing ability because they are excellent in dispersibility and reducing ability, and the product after the reduction treatment can be easily discharged as a gas (carbon monoxide).

  The average particle size of primary particles of such particles is preferably about 1 to 100 nm, and more preferably about 2 to 80 nm. By setting the particle size of the particles having the reducing ability within the above range, the semiconductor particles and the particles having the reducing ability are easily dispersed uniformly, and the opportunity for contact between the two is increased. As a result, a sufficient reduction treatment can be performed on the semiconductor particles.

  In addition, the content of the particles having reducing ability is appropriately set according to the particle size of the primary particles, but as an example, the content is preferably about 30 to 500% by volume of the content of the semiconductor particles. More preferably, it is about ~ 400% by volume. Thereby, the contact opportunity between the semiconductor particles and the particles having the reducing ability can be further increased, and the particles having the reducing ability can be prevented from becoming excessive.

  In addition, what is necessary is just to make it improve the dispersibility of each particle | grain by giving an ultrasonic wave and a vibration to the mixed dispersion liquid which added the particle | grains which have reducing ability as needed.

  Next, in the compounding step, the obtained mixed dispersion is powdered and dried. At this time, a reduction reaction occurs between the semiconductor particles and the particles having reducing ability due to heating. For example, in the case of carbon particles, oxygen in the semiconductor particles and carbon in the carbon particles react to generate carbon monoxide. Since this carbon monoxide is discharged together with the high-pressure gas, it is possible to efficiently form composite particles and reduce semiconductor particles.

  In this case, the high-pressure gas may be any of a reducing gas, an inert gas, an oxidizing gas, and the like, but is preferably an inert gas in order to prevent unintended oxidation and reduction.

  Note that the reduction treatment described above can be replaced by microwave treatment, high-frequency ultrasonic treatment, laser irradiation treatment, or the like. In any of these treatments, a reduction treatment can be performed by causing a reaction between semiconductor particles and particles having a reducing ability by the energy of microwaves, high-frequency ultrasonic waves, and lasers.

  In particular, since carbon particles are easily absorbed by microwaves, lasers, etc., the carbon particles can directly self-heat with less energy. As a result, the reduction process can be performed more efficiently than when heated from the outside, and the temperature of the carbon particles is increased uniformly, so that the uniformity of the reduction process is improved. As a result, the progress of the reduction process can be strictly controlled.

When performing such a process, the process may be performed on the droplets of the mixed dispersion liquid as in the first embodiment. Thereby, volatilization of the dispersion medium and reduction treatment can be performed to produce composite particles.
The frequency of the microwave is, for example, about 1 to 30 GHz.

In the present embodiment as described above, the same operations and effects as in the first embodiment can be obtained.
In addition, since it is not necessary to use a gas having reducing ability, the manufacturing cost can be reduced. In particular, by using microwave treatment, high-frequency ultrasonic treatment, laser irradiation treatment, or the like, particles having reducing ability can be directly heated, so that energy efficiency is high and manufacturing cost can be further reduced.

<Third Embodiment>
Next, a third embodiment of the method for producing composite particles of the present invention will be described.

  In the following, the third embodiment will be described. The description will focus on the differences from the first embodiment, and the description of the same matters will be omitted.

  In this embodiment, instead of using a gas having a reducing ability, a mixed dispersion (intermediate of composite particles) and a simple substance or alloy having a reducing ability coexist in the same space, and these are heated. Except for the above, it is the same as the first embodiment.

  In the present embodiment, a core tube having an inner wall made of a metal or alloy having a reducing ability is used as the core tube 121 of the spray drying apparatus 100. By using such a core tube 121, the semiconductor particles can be subjected to a reduction treatment by bringing the droplets of the mixed dispersion into contact with the inner wall surface of the core tube 121 under heating in the compounding step. it can. As a result, simply passing the mixed dispersion liquid through the core tube 121 (or a pipe instead thereof) allows continuous and efficient reduction treatment, and increases the mass productivity of the composite particles.

  Examples of the metal having a reducing ability include copper, titanium, aluminum and the like. Moreover, as an alloy of these metals, the intermetallic compound containing the said 2 or more types of said metals or the said metal, and the other metal is mentioned.

  Of these, reduction treatment can be performed particularly efficiently by using copper as the metal having reducing ability. Further, although copper is oxidized by the reduction treatment, copper oxide can be easily reduced, so that there is an advantage that reuse is easy.

  Further, the metal or alloy having the reducing ability may be used in a form other than the inner wall surface of the core tube 121. As such a form, for example, a net-like body, a slit-like body provided so as to cross the inside of the core tube 121, a plate-like body arranged in parallel along the longitudinal direction of the core tube 121, or the like may be used. Good. All of these forms provide sufficient opportunities for contact between the semiconductor particles and the metal or alloy having the reducing ability without hindering the flow of the mixed dispersion, so that reliable reduction treatment and high mass production are possible. It is compatible with sex. In addition, since any of these forms of metals or alloys can be easily replaced, they are also useful from the viewpoint of ease of maintenance of the apparatus.

  The form of the metal or alloy having reducing ability may be a simple lump, plate, rod, powder, flake or the like. Further, the mixed dispersion does not necessarily have to be reduced in the pipe, and the reduction treatment is performed by coexisting with a metal or alloy having a reducing ability in a simple container and subjecting it to heat treatment. In this case, the cost required for the facility can be reduced.

  In addition, among the said forms, since the powder and flake-like body have a large surface area, the efficiency of a reduction process is high.

  The atmosphere in the reduction treatment is not particularly limited and may be any of a reducing gas, an inert gas, and an oxidizing gas, but is an inert gas in order to prevent unintended oxidation and reduction. Is preferred.

Using the apparatus as described above, composite particles are produced in the same manner as in the first embodiment.
In this embodiment as well, the same operations and effects as in the first embodiment can be obtained.

  In addition, since it is not necessary to prepare gas having reducing ability, particles having reducing ability, etc., the manufacturing cost can be greatly reduced.

(Resin composition)
The resin composition of the present invention has the composite particles of the present invention and a curable resin. Such a resin composition can easily supply (apply) the composite particles of the present invention to various devices without using an expensive vacuum apparatus or heat treatment at a high temperature by using various application methods. And can be fixed. Thereby, the wavelength conversion function mentioned above can be added with respect to various devices, and the function improvement of various devices can be aimed at.

  As the curable resin, a photocurable resin, a thermosetting resin, or the like can be used, and in particular, a resin having light permeability is preferably used. Examples of such curable resins include epoxy resins, acrylic resins, silicone resins, and ethylene vinyl acetate (EVA) resins. By using these, the light transmittance of the resin composition can be further enhanced.

  Among these, examples of the epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, naphthalene type epoxy resins or hydrogenated products thereof, epoxy resins having a dicyclopentadiene skeleton, and triglycidyl. Examples thereof include an epoxy resin having an isocyanurate skeleton, an epoxy resin having a cardo skeleton, and an epoxy resin having a polysiloxane structure. When the resin composition requires heat resistance, such as directly forming a photovoltaic layer such as amorphous silicon or an antireflection film, those having an alicyclic structure are preferred. Examples of the alicyclic epoxy resin include 3,4-epoxycyclohexylmethyl 3 ′, 4′-epoxycyclohexanecarboxylate, 1,2,8,9-diepoxylimonene, and ε-caprolactone oligomer at both ends, respectively. Examples include an ester-bonded 4-epoxycyclohexylmethanol and 3,4-epoxycyclohexanecarboxylic acid, a hydrogenated biphenyl skeleton, and an alicyclic epoxy resin having a hydrogenated bisphenol A skeleton.

  The acrylic resin is not particularly limited as long as it is a (meth) acrylate having two or more functional groups, but a resin composition such as directly forming a photovoltaic layer or an antireflection film such as amorphous silicon. When heat resistance is required, those having an alicyclic structure are preferable. As the (meth) acrylate having an alicyclic structure, an acrylic resin obtained by polymerizing at least one (meth) acrylate selected from the following general formula (1) and general formula (2) is particularly preferable.

［一般式（１）中、Ｒ^１およびＲ^２は、互いに異なっていてもよく、水素原子またはメチル基である。また、ａは１または２であり、ｂは０または１である。］

[In General Formula (1), R ¹ and R ² may be different from each other, and are a hydrogen atom or a methyl group. Further, a is 1 or 2, and b is 0 or 1. ]

More preferably, in the general formula (1), R ¹ and R ² are hydrogen, a is 1 and b is 0. In the general formula (2), X is — Perhydro-1,4; 5,8-dimethananaphthalene-2,3,7- (oxymethyl) tri having a structure in which CH ₂ OCOCH═CH ₂ , R ³ , R ⁴ are hydrogen and P is 1 An acrylate, and at least one acrylate selected from acrylates having a structure in which X, R ³ and R ⁴ are all hydrogen and P is 0 or 1, are more preferable in consideration of viscosity and the like. In this case, norbornane dimethylol diacrylate having a structure in which X, R ³ and R ⁴ are all hydrogen and P is 0 is used.

  A water-dispersed acrylic resin can be used as the acrylic resin. A water-dispersed acrylic resin is an acrylic monomer, oligomer, or polymer that is dispersed in a dispersion medium containing water as the main component. In a dilute state like an aqueous dispersion, the crosslinking reaction hardly proceeds, but water is evaporated. If this is done, the crosslinking reaction will proceed and solidify at room temperature, or it will have a functional group capable of self-crosslinking, and it will be crosslinked and solidified only by heating without the use of additives such as catalysts, polymerization initiators, and reaction accelerators. Acrylic resin.

  In the former type, the crosslinking reaction hardly proceeds in a dilute state such as an aqueous dispersion, and if water is evaporated and the crosslinking reaction proceeds and solidifies at room temperature, it is not particularly limited. Additives such as a polymerization initiator and a reaction accelerator may be used, or a functional group capable of self-crosslinking may be used. Further, heating for the purpose of completing the reaction is not limited. The self-crosslinkable functional group is not particularly limited. For example, carboxyl groups, epoxy groups, methylol groups, vinyl groups, primary amide groups, alkoxysilyl groups, methylol groups and alkoxymethyl groups, carbonyl groups And hydrazide group, carbodiimide group and carboxyl group. The water-dispersed acrylic resin is suitably used when the composite particles containing the wavelength conversion substance have an affinity for water.

On the other hand, examples of the silicone-based resin include commercially available silicone resins for LEDs.
In addition, as the ethylene vinyl acetate resin having crosslinkability, those having a vinyl acetate content (VA content) of 25% by weight or more are preferably used. For example, Solar Eva (trademark) manufactured by Mitsui Chemicals Fabro Co., Ltd. is suitable. Can be used.

  Note that the curable resin as described above may be any resin that finally forms a network structure, and ionomer resins that form a network using ions as a medium can also be used.

  Although content (volume fraction) of curable resin is not specifically limited, It is preferable that it is 20-65 volume% of the whole resin composition, and it is more preferable that it is especially 30-55 volume%. When the content is within the above range, the light emission characteristics and durability are particularly excellent.

  On the other hand, the content (volume fraction) of the composite particles is not particularly limited, but is preferably 30 to 70% by volume, more preferably 40 to 60% by volume, based on the entire resin composition. When the content is within the above range, particularly the moldability of the resin composition can be ensured, and since the filling property of the composite particles in the resin composition is ensured, the composite particles are regularly and uniformly. It becomes easy to arrange. As a result, when the resin composition is molded into a layer, the transparency of the layer is increased.

  In addition to the above-described curable resin and composite particles, the resin composition of the present invention improves the affinity between the catalyst for promoting crosslinking, a crosslinking agent, other wavelength converting substances, and composite particles and the resin. In addition, various additives such as a compound having an alkoxy group for improving the dispersibility of the composite particles, a coupling agent, and a surfactant may be contained.

  Examples of such additives include silicon alkoxide compounds such as tetraethoxysilane and tetramethoxysilane, various coupling agents containing silicon such as aminosilane, epoxysilane, and acrylic silane, and silicon other than silicon such as aluminum and titanium. Examples thereof include an alkoxy group-containing compound containing an element.

  Further, when the composite particles containing zinc oxide semiconductor particles are dispersed in the curable resin, it is preferable to use a silane coupling agent containing silicon as a dispersant. As the silane coupling agent, those having nitrogen or an amino group are preferably used, and aminosilane, azasilane and the like are preferably used. When aminosilane is used, disilane having a bifunctional alkoxy group or monosilane having a monofunctional alkoxy group is preferable, and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane and the like are preferable from the balance of cost and performance. Preferably used. When azasilane is used, cyclic azasilane or the like is preferably used, and 2,2-dimethoxy-1,6-diaza-2-silacyclooctane or N-methyl-aza-2,2,4 is used from the balance of cost and performance. -Trimethylsilacyclopentane and the like are preferably used.

(Wavelength conversion layer and photovoltaic device)
The wavelength conversion layer of the present invention is formed by molding and curing the resin composition of the present invention into a predetermined shape. Such a wavelength conversion layer can make light of a specific wavelength incident on various devices by changing the emission wavelength with respect to the absorption light wavelength.

  Moreover, the photovoltaic device of the present invention has the wavelength conversion layer of the present invention. For this reason, the photovoltaic device excellent in photoelectric conversion efficiency is obtained by selecting suitably the light emission wavelength in a wavelength conversion layer according to the photoelectric conversion characteristic in a photovoltaic device.

<First Embodiment>
First, a first embodiment of the wavelength conversion layer of the present invention and the photovoltaic device of the present invention will be described.

  As described above, the photovoltaic device 1 (photovoltaic device of the present invention) 1 shown in FIG. 1 includes a photovoltaic layer 2 that generates an electromotive force in response to light irradiation, and the light of the photovoltaic layer 2. It has the wavelength conversion layer (wavelength conversion layer of this invention) 3 provided in the entrance plane side, and comprised with the hardened | cured material of the resin composition of this invention.

  The photovoltaic layer 2 generates electromotive force by light, and includes a semiconductor layer composed of a p-type semiconductor layer, an intrinsic semiconductor layer, and an n-type semiconductor layer, a sealing material such as an EVA resin composition, and one surface of the semiconductor layer. Or the transparent electrode layer provided in the surface of both sides is provided.

  The material constituting the semiconductor layer is not particularly limited as long as it is a semiconductor material, and examples thereof include single crystal silicon, polycrystalline silicon, spherical silicon, amorphous silicon, a compound semiconductor, an organic semiconductor, and a quantum dot semiconductor.

  The transparent electrode is not particularly limited, and is formed of, for example, an ITO film or a tin oxide film. The configuration of the photovoltaic device 1 is not limited to this, and can be applied to various photovoltaic devices 1. In particular, when a commercially available photovoltaic layer 2 is prepared and the wavelength conversion layer 3 is attached thereto, glass, a transparent electrode, a non-reflective layer, a protective layer, etc. are further formed on the photovoltaic layer 2. preferable. In this case, the wavelength conversion layer 3 may be attached on or below glass, a transparent electrode, a non-reflective layer, a protective layer, or the like. The wavelength conversion layer 3 converts sunlight in the ultraviolet region into a visible light region or a near infrared region. Alternatively, infrared rays in the infrared region are converted into a visible light region or a near infrared region. The converted sunlight is incident on the photovoltaic layer 2. Therefore, compared with the case where the wavelength conversion layer 3 is not provided, the photoelectric conversion efficiency in the photovoltaic layer 2 is increased, and when an organic material is used for the photovoltaic layer 2, the deterioration thereof can be suppressed. it can. As a result, the lifetime of the photovoltaic layer 2 such as a photoelectric conversion layer in a solar cell is improved.

  In this embodiment, the wavelength conversion layer 3 includes a curable resin 5 and composite particles 4 dispersed in the curable resin 5, as shown in FIG. As described above, the composite particles 4 control the activity of the semiconductor particles and can be uniformly dispersed in the curable resin 5. Therefore, in the wavelength conversion layer 3, the composite particles 4 are curable resin 5. Evenly distributed in the interior. Therefore, the wavelength conversion layer 3 can make the wavelength-converted light uniformly incident on the entire photovoltaic layer 2.

  Such a wavelength conversion layer 3 is formed by, for example, applying the above-described resin composition to the surface of the photovoltaic layer 2 and curing it. For this reason, for example, the wavelength conversion layer 3 can be formed only by apply | coating a resin composition to the commercially available photovoltaic layer 2, and making it photocure.

  Examples of the coating method include a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, a die coating method, an ink jet method, and a dispenser method.

  Note that the photovoltaic device 1 can be applied to various devices such as EL illumination, optical communication, EL display, LED illumination, solar cell, bioimaging, and the like.

Second Embodiment
Next, a second embodiment of the photovoltaic device of the present invention will be described.
FIG. 4 is a cross-sectional view schematically showing a second embodiment of the photovoltaic device of the present invention.

  Hereinafter, although the second embodiment will be described, the description will focus on the differences from the first embodiment, and the description of the same matters will be omitted. In the present embodiment, the same components as those of the first embodiment are denoted by the same reference numerals as those of the components described above, and detailed description thereof is omitted.

  The present embodiment is the same as the first embodiment except that the photovoltaic device 1 has two wavelength conversion layers 3.

  The photovoltaic device 1 shown in FIG. 4 includes, as the wavelength conversion layer 3, a first wavelength conversion layer 31 that converts sunlight in the ultraviolet region into a visible light region or a near infrared region, and visible sunlight in the infrared region. And a second wavelength conversion layer 32 that converts the light region or the near infrared region. In the second embodiment, as shown in FIG. 4, a first wavelength conversion layer 31 and a second wavelength conversion layer 32 are provided in this order above the photovoltaic layer 2 from the light incident side.

  In general, the longer the wavelength of light, the easier it is to pass through the object. Therefore, the first wavelength conversion layer 31 that converts the relatively short wavelength ultraviolet region into the visible light region is used as the incident light of the photovoltaic layer 2. The amount of light incident on the wavelength conversion layers 31 and 32 by providing the second wavelength conversion layer 32 provided on the upstream side and converting the infrared region having a relatively long wavelength into the visible light region on the downstream side of the incident light. Can be secured more. In the first wavelength conversion layer 31, ultraviolet rays of sunlight are converted into a visible light region or a near infrared region, and in the second wavelength conversion layers 32, infrared rays of sunlight are converted into a visible light region or a near infrared region. By converting into the region, the amount of visible light (or near-infrared region) incident on the photovoltaic layer 2 increases. As a result, the photoelectric conversion efficiency in the photovoltaic layer 2 can be increased.

  In addition, the 2nd wavelength conversion layer 32 is not limited to the layer which converts the sunlight ray of an infrared region into a visible light region, Like the 1st wavelength conversion layer 31, it converts the sunlight ray of an ultraviolet region into a visible light region. It is a wavelength conversion layer, Comprising: The 1st wavelength conversion layer 31 may differ in a composition.

Further, the number of wavelength conversion layers 3 stacked is not limited to two but may be three or more.
In addition, the refractive index of the wavelength conversion layer 3 is such that the refractive index of the layer located upstream of the incident light is the smallest, and the refractive index increases as the layer closer to the photovoltaic layer 2 increases. The loss accompanying the reflection of light in can be suppressed, and the light transmittance of the wavelength conversion layer 3 can be increased. As a result, the amount of light incident on the photovoltaic layer 2 is increased, and the photovoltaic device 1 with high photoelectric conversion efficiency is obtained.

  In addition, the first wavelength conversion layer 31 and the second wavelength conversion layer 32 are formed by sequentially forming a film above the photovoltaic layer 2, but separately, the resin composition of the present invention is formed into a film. The film formed and cured may be formed by adhering to the photovoltaic layer 2 with an adhesive or the like.

  In the present embodiment as described above, the same operations and effects as those in the first embodiment can be obtained.

<Third Embodiment>
Next, a third embodiment of the photovoltaic device of the present invention will be described.
FIG. 5 is a cross-sectional view schematically showing a third embodiment of the photovoltaic device of the present invention.

  In the following, the third embodiment will be described. The description will focus on the differences from the first embodiment, and the description of the same matters will be omitted. In the present embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals as those described above, and detailed description thereof is omitted.

  This embodiment is the same as the second embodiment except that the arrangement of the two wavelength conversion layers 3 is different.

  The photovoltaic device 1 shown in FIG. 5 has a first wavelength conversion layer 31 provided above the photovoltaic layer 2 and a second wavelength conversion layer 32 provided below the photovoltaic layer 2. is doing.

  As described above, the longer the wavelength of light, the easier it is to transmit light. Therefore, the infrared region having a relatively long wavelength has a transmission power enough to pass through the photovoltaic layer 2 as well. For this reason, even if the second wavelength conversion layer 32 for converting the infrared region into the visible light region is provided below the photovoltaic layer 2, the second wavelength conversion layer 32 has a sufficient amount of infrared region. Can receive sunlight.

  Further, the photovoltaic device 1 shown in FIG. 5 has a reflective layer 7 provided below the second wavelength conversion layer 32. The reflective layer 7 reflects light that has been sequentially transmitted through the first wavelength conversion layer 31, the photovoltaic layer 2, and the second wavelength conversion layer 32 upward. As a result, light that would not have contributed to photoelectric conversion without the reflective layer 7 can be incident on the photovoltaic layer 2 again. As a result, the amount of light incident on the photovoltaic layer 2 increases, and the photovoltaic device 1 with high photoelectric conversion efficiency is obtained.

  Furthermore, in this embodiment, since the second wavelength conversion layer 32 is provided below the photovoltaic layer 2 and the reflection layer 7 is further provided below the second wavelength conversion layer 32, the second wavelength conversion layer 32 is reflected by the reflection layer 7. The light before being transmitted and the light after being reflected by the reflective layer 7 are transmitted. For this reason, in this embodiment, the wavelength conversion opportunity in the 2nd wavelength conversion layer 32 becomes twice, and wavelength conversion efficiency becomes higher. From this viewpoint, the photoelectric conversion efficiency of the photovoltaic device 1 can be further improved.

  In addition, although the 1st wavelength conversion layer 31 and the 2nd wavelength conversion layer 32 are each formed by forming into a film on each surface of the photovoltaic layer 2, otherwise, the resin composition of this invention is made into a film form separately. It may also be formed by bonding a film formed and cured to the photovoltaic layer 2 with an adhesive or the like.

  Also in the present embodiment as described above, the same operations and effects as in the first embodiment can be obtained.

<Fourth embodiment>
Next, a fourth embodiment of the photovoltaic device of the present invention will be described.

  6 to 11 are a sectional view and a plan view, respectively, schematically showing a fourth embodiment of the photovoltaic device of the present invention.

  In the following, the fourth embodiment will be described. The description will focus on the differences from the first embodiment, and the description of the same matters will be omitted. In the present embodiment, the same components as those of the first embodiment are denoted by the same reference numerals as those of the components described above, and detailed description thereof is omitted.

  In the present embodiment, the photovoltaic device is the same as that in the first embodiment, except that the photovoltaic device has a regularly distributed cured product of the dot-like resin composition.

  The photovoltaic device 1 shown in FIG. 6 (a) is provided above the photovoltaic layer 2, and has a plurality of cured products of the resin composition having a dot-like form. The cured products of the plurality of resin compositions are spaced from each other at substantially equal intervals, and are regularly arranged on the upper surface of the photovoltaic layer 2. In other words, the wavelength conversion layer 3 has a concavo-convex structure formed of the cured product of the resin composition of the present invention formed on the upper surface of the photovoltaic device 1. In the case of the wavelength conversion layer 3 shown in FIG. 6B, the wavelength conversion layer 3 has a discontinuous structure because the cured product of the resin composition having a dotted shape is scattered. However, even in such a structure, it is referred to as a wavelength conversion layer in this specification.

  When the wavelength conversion layer 3 has a concavo-convex structure, when the light incident on the cured product of one resin composition is reflected, there is a probability that the light is reflected not in the upper direction of FIG. Get higher. The light reflected in the left-right direction is incident again on the adjacent cured product and incident on the photovoltaic layer 2 with refraction. As a result, when the wavelength conversion layer 3 does not have a concavo-convex structure, the light incident on the photovoltaic layer 2 is lost due to reflection, whereas the wavelength conversion layer 3 shown in FIG. In this case, a part of the light that should have been lost if there was no concavo-convex structure can be made incident on the photovoltaic layer 2. That is, the wavelength conversion layer 3 shown in FIG. 6 has an antireflection function in addition to the wavelength conversion function as described above. As a result, the photoelectric conversion efficiency in the photovoltaic device 1 can be further increased.

  The height difference of the concavo-convex structure is preferably from 300 nm to 100 μm, more preferably from 1 to 50 μm, and even more preferably from 10 to 50 μm, from the balance between the absorption of sunlight from the oblique direction and the cost. . The height difference of the concavo-convex structure can be measured using various microscopes such as an atomic force microscope, a confocal microscope, and a laser microscope.

  The in-plane period of the concavo-convex structure is preferably 300 nm to 50 μm. By setting the in-plane period of the concavo-convex structure within the above range, the probability that light is reflected on the surface of the concavo-convex structure can be particularly reduced, and the antireflection function of the concavo-convex structure can be particularly enhanced.

  Furthermore, it is preferable that the period is substantially equal to or less than the absorption wavelength region of the wavelength conversion layer 3. Thereby, when light enters the wavelength conversion layer 3, Fresnel reflection hardly occurs. Then, regardless of the shape of the concavo-convex structure, the reflection of light by the wavelength conversion layer 3 is reduced, and the amount of light incident on the wavelength conversion layer 3 is further increased. As a result, the amount of light incident on the photovoltaic layer 2 also increases.

  Moreover, the uneven | corrugated period of an in-plane perpendicular direction (X direction, Y direction) may be the same, or may differ. There may also be variations in the in-plane cycle in the same direction. The in-plane period of the concavo-convex structure is obtained by Fourier transforming image information acquired using various microscopes such as an atomic force microscope, a confocal microscope, a laser microscope, and a field emission scanning electron microscope (FE-SEM). Can do.

  Examples of the shape of the concavo-convex structure include various shapes such as dots, microlenses, line and space (L & S), honeycombs, cells, square pyramids, moth eyes, and cones. From the viewpoint of cost and efficiency, the shape of a dot, microlens, L & S, cell, or quadrangular pyramid is preferable, and the shape of a dot or microlens is more preferable.

  The concavo-convex structure shown in FIGS. 6 to 8 and FIG. 11 is an example of the concavo-convex structure in the form of dots or microlenses. These concavo-convex structures have a substantially circular shape in plan view, while the vertical cross-sectional shape has a substantially semicircular shape.

  In addition to the discontinuous structure as shown in FIG. 6, the uneven structure provided in the wavelength conversion layer 3 is a resin composition having a flat plate shape covering the upper surface of the photovoltaic layer 2 as shown in FIG. 7. It may be a structure of a laminate of the cured product and a cured product of the resin composition that is provided on the cured product and has a regularly distributed spot shape. If it is such a structure, the light which injected into area | regions other than the hardened | cured material of the resin composition which makes a dot-like form also injects into the wavelength conversion layer 3, and can convert the wavelength. In other words, according to the wavelength conversion layer 3 shown in FIG. 7, the wavelength conversion can also be performed on the light that could not be converted by the wavelength conversion layer 3 shown in FIG. 6. The ratio of light in the wavelength region that can be photoelectrically converted can be increased.

  In the uneven structure, the distribution of the cured product of the resin composition in the form of a dot may be regular or irregular. In the case of regularity, the pattern of distribution is not particularly limited.

  Further, as shown in FIG. 8A, the concavo-convex structure is convex on the photovoltaic layer 2 side as shown in FIG. 8B, even if the light irradiation side (upstream side) is convex. However, from the viewpoint that a large amount of light is incident on the photovoltaic layer 2, it is preferable that the photovoltaic layer 2 side is convex. In this case, the concavo-convex structure may be embedded in the photovoltaic layer 2 as shown in FIG. In this case, the in-plane period of the concavo-convex structure is preferably in the range of 300 nm to 1 μm.

  Moreover, even if the uneven | corrugated structure is comprised with the same resin composition, the adjacent unevenness | corrugation may be comprised with a different resin composition. When the light absorption wavelength range of the resin composition is relatively narrow, the power generation efficiency of the photovoltaic device 1 is set by setting the adjacent uneven resin composition different for the purpose of, for example, widening the light absorption wavelength range. Can be improved easily.

  Furthermore, as shown in FIG. 8C, the concavo-convex structure may have a smaller fine concavo-convex shape at each convex portion. Thereby, the light confinement effect is generated by the fine uneven shape, and the reflection of light by the wavelength conversion layer 3 can be further reduced. The height difference of the fine uneven shape is preferably 100 to 500 nm.

  The concavo-convex structure is a structure in which the concavo-convex structure of FIG. 8A and the concavo-convex structure of FIG. 8B are combined, that is, both the light irradiation side and the photovoltaic layer 2 side are convex. Such a structure may be used (see FIG. 8D). In this case, it is preferable that the in-plane period of the concavo-convex structure in which the photovoltaic layer 2 side is convex is smaller than the in-plane period of the concavo-convex structure in which the side irradiated with light is convex. Thereby, the light quantity which injects into the photovoltaic layer 2 can be increased.

  Moreover, it is preferable that the in-plane position of the concavo-convex structure where the photovoltaic layer 2 side is convex and the in-plane position of the concavo-convex structure where the side irradiated with light is convex are shifted from each other. Thereby, the area of the wavelength conversion layer 3 in a plan view can be secured larger, and the amount of light incident on the wavelength conversion layer 3 can be increased.

  Moreover, the concavo-convex structure shown in FIG. 9 is an example of the concavo-convex structure having an L & S shape. Specifically, as shown in FIG. 9B, the concavo-convex structure shown in FIG. 9 has an elongated plan view shape extending along the Y direction, while the longitudinal sectional shape is substantially semicircular. ing.

  Furthermore, the concavo-convex structure shown in FIG. 10 is also an example of the concavo-convex structure having an L & S shape. However, the concavo-convex structure shown in FIG. 10 is an elongated shape extending along the Y direction as shown in FIG. A cured product of a plurality of resin compositions having a shape in plan view and provided at equal intervals, and a cured product of a plurality of resin compositions provided in an elongated plan view shape extending in the X direction at equal intervals. Are arranged so as to be orthogonal to each other. Thereby, the concavo-convex structure shown in FIG. 10 has a lattice shape in plan view.

  Further, the concavo-convex structure shown in FIG. 11 is composed of a cured product of a resin composition having a regularly distributed spot shape, but each cured product has a two-layer structure, and is composed of a lower layer and an upper layer. The types of the resin composition constituted by are different.

The combination of the types of resin compositions is not particularly limited. For example, the resin composition constituting the upper layer is made the same as the resin composition constituting the first wavelength conversion layer 31 in the second embodiment, and the lower layer is formed. What is necessary is just to make the resin composition to comprise the same with the resin composition which comprises the 2nd wavelength conversion layer 32 in 2nd Embodiment. That is, in the upper layer (first wavelength conversion layer 31), ultraviolet rays in the ultraviolet region are converted into the visible light region or near infrared region, and in the lower layer (second wavelength conversion layer 32), sunlight in the infrared region is visible. It is converted into the light region or near infrared region. Thereby, the light quantity of visible light (or near infrared region) which injects into the photovoltaic layer 2 increases. As a result, the photoelectric conversion efficiency in the photovoltaic layer 2 can be increased.
Note that the concavo-convex structure shown in FIG. 11 may be formed of a laminate of three or more layers.

  The wavelength conversion layer 3 having the concavo-convex structure as described above is formed by applying the resin composition of the present invention by various application methods as described above, and then curing the applied product. It is preferable to apply by an inkjet method. According to the inkjet method, a predetermined amount of the resin composition can be accurately applied to a desired region. For this reason, the shape of the concavo-convex structure can be accurately reproduced.

  Moreover, it is preferable to perform a surface treatment on the coated surface in advance so as to control the liquid repellency of the resin composition. Thereby, the resin composition discharged by the inkjet method is naturally formed into a hemispherical shape by the surface tension. As a result, the wavelength conversion layer 3 as shown in FIG. 6 can be more easily formed.

  Inkjet devices include various ejection methods such as a piezo method, an electrostatic method, and a thermal method. From the viewpoint that a relatively high viscosity resin composition can be ejected, a piezo method or an electrostatic method ink jet is available. An apparatus is preferably used.

  Further, after forming the concavo-convex structure, another resin composition may be overcoated on the concavo-convex structure. Thereby, the fall of stain resistance, durability, etc. in the photovoltaic apparatus 1 can be suppressed.

  In the present embodiment as described above, the same operations and effects as those in the first embodiment can be obtained.

  The embodiments of the composite particle manufacturing method, composite particles, resin composition, wavelength conversion layer, and photovoltaic device of the present invention have been described above, but the present invention is not limited to this, and for example, photovoltaic Arbitrary components may be added to the electric device.

Next, specific examples of the present invention will be described.
Example 1

1. Preparation of composite particles, resin composition and wavelength conversion layer <1> First, ethanol was added so that the concentration of zinc acetate dihydrate (Zn (CH ₃ COO) ₂ .2H ₂ O) was 0.1 M, 400 ml of an ethanol solution of zinc acetate dihydrate was prepared. The ethanol solution was concentrated with heating and stirring at about 80 ° C. for about 3 hours until the total amount of the solution reached 120 ml. After concentration, 120 ml of ethanol was added and cooled to room temperature. Next, the obtained ethanol solution was added so that the concentration of lithium hydroxide monohydrate (LiOH.H ₂ O) was 0.14 M, and sonicated at a temperature of 23 ° C. or lower for 20 minutes. As a result, 400 ml of an ethanol dispersion was obtained. This ethanol dispersion emitted green light when irradiated with ultraviolet rays, and it was confirmed that ethanol contained semiconductor particles.

  Then, hexane was added to 400 ml of the obtained ethanol solution, and centrifugation treatment was performed at 10,000 G for 1 minute. Hexane was added in such an amount that the volume ratio was about 3 (1200 ml) when the volume of the ethanol solution of semiconductor particles was 1. Thereafter, the supernatant was removed to obtain 4.9 g of a paste-like residue. Then, 400 ml of ethanol was added to the pasty residue and redispersed. As a result, an ethanol dispersion of the washed semiconductor particles was obtained.

<2> Next, an organosilica sol (product number: IPA-ST, average particle diameter of silica particles: about 12 nm, concentration of silica particles: 30% by weight, dispersion medium: 2-propanol) manufactured by Nissan Chemical Industries, Ltd. It was diluted about 34 times with ethanol to prepare a dispersion having a silica particle concentration of 0.15M. Next, 10 ml of this dispersion and 40 ml of an ethanol dispersion of semiconductor particles prepared in <1> were mixed to prepare a mixed dispersion.

  Next, the obtained mixed dispersion was dried by a spray drying method to obtain composite particles of semiconductor particles mainly containing zinc oxide and silica particles (inorganic compound particles). The furnace temperature during spray drying was 400 ° C., and the carrier gas used was 100% hydrogen. The inner wall surface of the furnace core tube of the spray dryer is made of stainless steel.

<3> 3.0 g of composite particles obtained by repeating the above operation were mixed with 100 g of ethanol, and dispersion treatment was performed using zirconia beads to obtain a transparent dispersion liquid in which the composite particles were dispersed.

<4> Norbornane dimethylol diacrylate having a structure in which X, R ³ and R ⁴ are all hydrogen and P is 0 in the general formula (2) (prototype No. TO-2111; manufactured by Toagosei Co., Ltd.) 0.30 g, N-methyl-aza-2,2,4-trimethylsilacyclopentane (manufactured by Gelest, SIM6501.4) 0.24 g, and 60 g of the composite particle transparent dispersion prepared in <3> were mixed. . Thereafter, the transparent dispersion was stirred at 40 ° C. under 30 hPa for 3 hours to remove volatile components.

  Then, 0.003 g of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Ciba Japan, Darocur 1173) was dissolved as a photopolymerization initiator in the transparent dispersion. Thereby, a resin composition was obtained.

<5> The resin composition obtained above was applied onto an ETFE (tetrafluoroethylene / ethylene copolymer) film having a surface treatment of 50 μm in thickness. The thickness after drying was about 20 μm. Then, the resin composition was cured by irradiating UV light of about 500 mJ / cm ² from both sides, and further heat-treated at about 180 ° C. under vacuum for 1 hour in a vacuum oven to remove the solvent. Thereby, the sheet-like hardened | cured material (wavelength conversion layer) of the resin composition was formed.

<6> Next, a solar cell sealing material EVA (VA content 28%, cross-linked type) sheet is laid on the CIGS solar cell, and the wavelength conversion layer of the resin composition obtained above is further formed thereon. The formed ETFE film was disposed so that the wavelength conversion layer faced downward (EVA sheet side). This was subjected to vacuum heat treatment to produce a photovoltaic device.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition and Photovoltaic Device <1> Particle Size Evaluation Silica particles in organosilica sol, ethanol dispersion of the obtained semiconductor particles and composite particles were evaluated as follows. .

  1) The Z average particle diameter of the primary particles of the semiconductor particles was measured by a dynamic light scattering apparatus (Zeta Sizer Nano ZS, manufactured by Malvern).

  2) The particle diameter of the semiconductor particles was observed with a field emission transmission electron microscope (FE-TEM, manufactured by Hitachi, Ltd., HF-2200). As an observation method, an image with an appropriate magnification was taken, 30 particles included in the image were randomly selected, the particle size was measured, and the average particle size was calculated. If necessary, the fine particles were embedded in a resin and the cross section was observed.

<2> Evaluation of light emission characteristics The following light emission characteristics were evaluated for the ethanol dispersion of the obtained composite particles and the wavelength conversion layer.

  1) An approximate emission peak wavelength was observed with a fluorescence spectrophotometer (F-2500, manufactured by Hitachi, Ltd.) under irradiation with an excitation absorption wavelength of 360 nm.

  2) Using an absolute PL quantum yield measuring apparatus (C9920-02G, manufactured by Hamamatsu Photonics Co., Ltd.), the fluorescence quantum yield when irradiated with near-ultraviolet light having wavelengths of 350 nm, 360 nm, and 370 nm was measured.

<3> Evaluation of Impurities etc. About the obtained composite particles, the ion content was measured using an ion chromatograph (Nihon Dionex Co., Ltd., ICS-2000 type ion chromatograph). As a measurement sample, 0.014 g of composite particles are precisely weighed in a polycarbonate container, 15 ml of ultrapure water is added, hydrothermal treatment is performed at 125 ° C. for 20 hours, and after cooling to room temperature, the inner solution is centrifuged and filtered. Solution. This solution and ion standard solution were introduced into an ion chromatograph, and each ion was quantified by a calibration curve method.

<4> Evaluation of thermogravimetric change The following thermogravimetric change was evaluated about the obtained paste-like residue, composite particle, and wavelength conversion layer.

  The weight reduction amount was measured using a differential heat / thermogravimetric simultaneous measurement device (TG / DTA6200R, manufactured by SII Nano Technology Co., Ltd.). Specifically, the temperature is increased from room temperature to a temperature of 500 ° C. at a rate of temperature increase of 10 ° C./min, and the weight decreases between 35 to 250 ° C. (a) and 250 to 500 ° C. (b) and the weight of the residue (c). % Was measured. From the results and various specific gravity data, the approximate volume ratio of the semiconductor particles and silica particles in the composite particles and the approximate volume ratio of the composite particles and resin components in the wavelength conversion layer were calculated.

<5> Evaluation of transparency The following transparency evaluation was performed about the ETFE film in which the wavelength conversion layer was formed.

  Total light transmittance and haze were measured using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH2000). The total light transmittance of the ETFE film alone was 94.2%, and the haze was 2.4.

<6> Light Resistance Evaluation Regarding the ETFE film on which the wavelength conversion layer is formed, a black panel temperature of 63 ° C., humidity of 50% RH, and irradiance of 100 mW / cm using an iSuper UV tester (SUV-W151, manufactured by Iwasaki Electric Co., Ltd.) ² (wavelength 300-400 nm), the light resistance test was done on condition of processing time 48 hours. Before and after the light resistance test, the case where the deterioration of the transparency and the light emission characteristics was less than 10% was evaluated as “Good”, and the case where the deterioration of at least one of the transparency and the light emission characteristics was more than 10% was evaluated as “X”.

<7> Evaluation of power generation efficiency The short-circuit current density Jsc (mA / cm ² ) and photoelectric conversion efficiency measurement of the photovoltaic device will be described. Irradiation of 1 kW / m ² of light using a simulated solar irradiation device (manufactured by Spectrometer Co., Ltd., OTENTO-SUNV type solar simulator), and the current and voltage generated at that time are measured by an IV tester (Keutley Instruments Co., Ltd.). ), 2400 type source meter), and measured according to JIS C 8913.

  Separately, a photovoltaic device produced in the same manner as described above was prepared as a comparative photovoltaic device, except that the wavelength conversion layer was not formed. The value obtained by subtracting the short-circuit current density Jsc measured for the comparative photovoltaic device from the short-circuit current density Jsc measured for the photovoltaic device obtained in Example 1 was defined as the short-circuit current density difference ΔJsc. .

In addition, after installing the obtained photovoltaic device outdoors for one month, the same evaluation as described above was performed, and when Jsc and photoelectric conversion efficiency were hardly decreased, the weather resistance was ○, and a remarkable decrease was observed. When it was seen, the weather resistance was set to x.
The above evaluation results are shown in Table 1.

(Example 2)
1. Preparation of composite particles, resin composition and wavelength conversion layer Composite particles, resin composition and wavelength were prepared in the same manner as in Example 1 except that the temperature of the furnace during spray drying was changed to 800 ° C. A conversion layer was obtained.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

(Example 3)
1. Preparation of composite particles, resin composition and wavelength conversion layer In preparation of composite particles, the carrier gas was changed to a mixed gas of hydrogen and nitrogen (hydrogen concentration 5%) and the furnace temperature during spray drying was changed to 800 ° C. Except that, composite particles, a resin composition, and a wavelength conversion layer were obtained in the same manner as in Example 1.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

Example 4
1. Preparation of composite particles, resin composition, and wavelength conversion layer In preparation of composite particles, composite particles were prepared using nitrogen as the carrier gas during spray drying, and the resulting composite particles were made into a batch-type electric furnace (manufactured by Motoyama Co., Ltd.). The composite particles, the resin composition, and the wavelength conversion layer were obtained in the same manner as in Example 1 except that they were put in an atmospheric electric furnace, SKM2030D) and subjected to heat treatment at 600 ° C. for 2 hours. The atmosphere in the batch type electric furnace was 100% hydrogen.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

(Example 5)
1. Preparation of composite particles, resin composition and wavelength conversion layer In preparation of composite particles, the carrier gas was changed to a mixed gas of hydrogen and nitrogen (hydrogen concentration 5%), and the furnace temperature during spray drying was set to 800 ° C. Except that the composite particles were prepared and the obtained composite particles were put into a batch type electric furnace (manufactured by Motoyama Co., Ltd., atmosphere type electric furnace, SKM2030D) and subjected to heat treatment at 600 ° C. for 2 hours. In the same manner as in Example 1, composite particles, a resin composition, and a wavelength conversion layer were obtained. The atmosphere in the batch type electric furnace was 100% hydrogen.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

(Example 6)
1. Preparation of Composite Particle, Resin Composition, and Wavelength Conversion Layer Composite particles, a resin composition, and a wavelength conversion layer were obtained in the same manner as in Example 1 except that the composite particles were prepared as follows.

  First, 1.0 g of carbon particles having an average particle diameter of 5 nm was further added to the mixed dispersion liquid containing semiconductor particles and inorganic compound particles.

  Next, the obtained mixed dispersion was dried by a spray drying method to obtain composite particles of semiconductor particles mainly containing zinc oxide and silica particles (inorganic compound particles). The furnace temperature during spray drying was 800 ° C., and nitrogen was used as the carrier gas. The inner wall surface of the furnace core tube of the spray dryer is made of stainless steel.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

(Example 7)
1. Production of composite particles, resin composition and wavelength conversion layer In preparation of composite particles, the temperature of the furnace during spray drying was set to 800 ° C., and the furnace core tube of the spray drying apparatus was attached to the inner wall with a stainless steel plate. A composite particle, a resin composition, and a wavelength conversion layer were obtained in the same manner as in Example 1 except that the product was changed to a manufactured product.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

(Example 8)
1. Preparation of Composite Particle, Resin Composition, and Wavelength Conversion Layer In the same manner as in Example 1, composite particles, a resin composition, and a wavelength conversion layer were obtained.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Except as described below, a photovoltaic device was produced in the same manner as in Example 1, and the photovoltaic device obtained was improved in power generation efficiency. Evaluation was performed. The evaluation results are shown in Table 1.

The obtained resin composition was apply | coated to the surface of an ETFE film so that it might become a micro lens shape (dot shape) using the commercially available inkjet apparatus (electrostatic system). Then, the resin composition was cured by irradiating UV light of about 500 mJ / cm ² from both sides, and further heat-treated at about 180 ° C. for 1 hour in a vacuum oven. As a result, a microlens-shaped cured product of the resin composition was formed. About the shape of the obtained cured product, when measured with a laser microscope (manufactured by Keyence Corporation, VK-9700), the diameter in plan view, the height difference of the concavo-convex structure, the period in the x-axis direction, the period in the y-axis direction, They were about 30 μm, about 20 μm, about 35 μm, and about 30 μm, respectively.

Thereafter, various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

(Comparative Example 1)
1. Preparation of composite particles, resin composition and wavelength conversion layer In the preparation of semiconductor particles, the cleaning with hexane was omitted, and in the preparation of composite particles, the composite was prepared in the same manner as in Example 1 except that the carrier gas was changed to nitrogen. Particles, a resin composition, and a wavelength conversion layer were obtained.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

(Comparative Example 2)
1. Preparation of composite particles, resin composition and wavelength conversion layer In the preparation of semiconductor particles, cleaning with hexane was omitted, and in the preparation of composite particles, the carrier gas was changed to nitrogen, and addition of organosilica sol was omitted, In the same manner as in Example 1, composite particles, a resin composition, and a wavelength conversion layer were obtained.

2. Evaluation of Semiconductor Particles, Composite Particles, Resin Composition, and Photovoltaic Device Various evaluations were performed in the same manner as in Example 1.
The above evaluation results are shown in Table 1.

  As is clear from Table 1, in the photovoltaic device obtained in each example, improvement in photoelectric conversion efficiency was recognized by providing the wavelength conversion layer.

  Moreover, in the photoelectric converting layer obtained by each Example, it was recognized that it is excellent in light resistance and a weather resistance compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 Photovoltaic apparatus 2 Photovoltaic layer 3 Wavelength conversion layer 31 1st wavelength conversion layer 32 2nd wavelength conversion layer 4 Composite particle 5 Curable resin 6 Semiconductor particle 7 Reflective layer 8 Inorganic compound particle 100 Spray drying apparatus 110 Sprayer 120 electric furnace 121 core tube 122 heater 130 bag filter 140 piping 150 piping

Claims (28)

A method for producing composite particles comprising zinc oxide semiconductor particles and inorganic compound particles,
A method for producing composite particles, comprising a step of reducing the intermediate of the composite particles at least once during the step of producing the composite particles.   The step of performing the reduction treatment includes heating the intermediate of the composite particles in a reducing atmosphere composed of a gas having a reducing ability and a mixed gas of a gas having a reducing ability and an inert gas. The method for producing composite particles according to claim 1.   The method for producing composite particles according to claim 2, wherein the gas having the reducing ability is hydrogen gas.   The method for producing composite particles according to claim 2 or 3, wherein a content of the gas having the reducing ability in the mixed gas is 1 to 10% by volume or 85 to 100% by volume. The intermediate of the composite particles includes particles having a reducing ability,
The method for producing composite particles according to claim 1, wherein the reduction treatment includes heat-treating the intermediate of the composite particles.   The method for producing composite particles according to claim 5, wherein the particles having the reducing ability are carbon particles.   2. The composite according to claim 1, wherein the reduction treatment is a process in which an intermediate of the composite particles and a single metal or alloy having a reducing ability coexist in the same space and heat-treat them. Particle manufacturing method.   The reduction treatment step heat-treats the pipe with at least the inner surface provided with the composite particle intermediate in the pipe made of the metal having a reducing ability or an alloy. The method for producing composite particles according to claim 7.   The method for producing composite particles according to claim 7 or 8, wherein the metal having a reducing ability is copper.   The method for producing composite particles according to any one of claims 1 to 9, wherein the reduction treatment is performed at 200 to 1,000 ° C.   The method for producing composite particles according to claim 1, wherein the reducing step is performed while performing the step of combining the semiconductor particles and the inorganic compound particles.   The method for producing composite particles according to claim 1, wherein the step of reducing treatment is performed after the step of combining the semiconductor particles and the particles of the inorganic compound.   The method for producing composite particles according to claim 11 or 12, wherein the step of combining is performed by a spray drying apparatus.   The method for producing composite particles according to any one of claims 1 to 13, wherein an average particle size of primary particles of the semiconductor particles is 1 to 10 nm.   The method for producing composite particles according to claim 1, wherein the inorganic compound particles are oxide particles. The method for producing composite particles according to claim 15, wherein the particles of the inorganic compound are at least one of silica (SiO ₂ ) particles and zirconia (ZrO ₂ ) particles.   The method for producing composite particles according to claim 1, wherein the content of the semiconductor particles is 10 to 90% by volume of the whole composite particles.   A composite particle obtained by the method for producing a composite particle according to claim 1.   A resin composition comprising the composite particles according to claim 18 and a curable resin.   The resin composition according to claim 19, wherein the content of the composite particles is 30 to 70% by volume of the entire resin composition.   A wavelength conversion layer obtained by curing a layer composed of the resin composition according to claim 19 or 20.   A photovoltaic device comprising the wavelength conversion layer according to claim 21.   The photovoltaic device according to claim 22, wherein the wavelength conversion layer has an uneven structure in a plane thereof.   The photovoltaic device according to claim 23, wherein a height difference of the concavo-convex structure is 300 nm to 100 µm.   The photovoltaic device according to claim 23 or 24, wherein an in-plane period of the concavo-convex structure is 300 nm to 50 µm.   The photovoltaic device according to any one of claims 23 to 25, wherein the concavo-convex structure has a fine concavo-convex shape smaller than the concavo-convex structure. It has a laminate formed by laminating two or more wavelength conversion layers,
27. The photovoltaic device according to any one of claims 23 to 26, wherein a shape of the uneven structure is different between the two wavelength conversion layers.   The photovoltaic device according to any one of claims 22 to 27, wherein the wavelength conversion layer is formed by supplying the resin composition by an ink jet method and curing the supplied resin composition.

Images