CN103186004A - Electrochromic device with nano-electrochromic material structure - Google Patents

Abstract

The invention discloses an electrochromic device with a nano electrochromic material structure. The electrochromic device mainly includes: the electrochromic device comprises a first transparent substrate, a transparent conducting layer, an electrochromic layer, a separation electrolyte layer, an ion storage layer, a transparent conducting layer and a second transparent substrate, wherein the electrochromic layer is composed of a nano material structure, so that the driving voltage required by the electrochromic device can be reduced, and the electrochromic element has the advantages of quick color change capability and prolonged service life.

Description

Electrochromic device with nano-electrochromic material structure

technical field

The present invention relates to an electrochromic device, in particular to an electrochromic device with a nanometer electrochromic material structure, the nanometer material can reduce the driving voltage required by the electrochromic element, has The advantages of rapid color change ability and extended service life.

Background technique

Generally speaking, an electrochromic device refers to a device that produces an electrochemical oxidation-reduction reaction when an electric field is provided, resulting in a change in light penetration characteristics, thereby causing a color change. Wherein, the process is a reversible process, and when there is no external electric field, the electrochromic material recovers its original characteristics. Utilizing the characteristics of electrochromic materials, electrochromic display devices can be made. Electrochromic materials can be used in various fields at present, such as: vehicle inlaid glass (such as car windows, skylights), building inlaid glass, display equipment, optical components, mirror bodies and shields for electromagnetic wave irradiation, etc., its function is to be able to Effectively block the interference of the outside world (such as light, heat). Among them, electrochromic materials are classified into reduction color materials and oxidation color materials. Reduction coloring materials refer to those that develop color due to gaining electrons, generally including tungsten oxide; at the same time, oxidation coloring materials refer to those that develop color due to loss of electrons, generally including nickel oxide and cobalt oxide; others include inorganic metal oxides. Electroluminescence materials such as: Ir(OH)x, MoO ₃ , V ₂ O ₅ , TiO ₂ and so on. It is worth noting that the above electroluminescent materials must be in an electrolyte environment containing lithium ions or hydrogen ions to produce color changes.

With perseverance, the applicant has developed an electrochromic element, the electrochromic layer of which contains several nanometer materials. With the nanometer material, the electrochromic element has the advantages of lower driving voltage, rapid discoloration ability and prolonged service life.

Contents of the invention

The main purpose of the present invention is an electrochromic element, the electrochromic layer of which contains several nanometer materials, by which the electrochromic element has a lower driving voltage, has fast color changing ability and prolongs the service life The advantages.

In order to solve the above problems, the present invention provides an electrochromic device with a nano-electrochromic material structure, comprising: a first transparent substrate with a transparent conductive layer on its upper surface; an electrochromic layer formed on the On the transparent conductive layer of the first transparent substrate, the electrochromic layer includes a plurality of nanowires; an ion-conducting electrolyte layer is formed on the electrochromic layer; an ion storage layer is formed on the electrolyte layer; And a second transparent substrate, the lower surface of which has a transparent conductive layer on the ion storage layer, so that the conductive layer is sandwiched between the ion storage layer and the second transparent substrate.

According to a feature of the present invention, the nanowires in the electrochromic layer are selected from one or a combination of zinc oxide nanowires, tungsten oxide nanowires, molybdenum oxide nanowires, or tungsten molybdenum oxide nanowires.

The present invention has following effect:

1. The driving voltage of the electrochromic device is between 1 volt and 4 volts. Compared with the general driving voltage of 40 volts to 80 volts, there is a large and obvious gap, which can achieve the function of reducing the operating voltage and saving energy.

2. High redox times and long service life. The electrochromic layer, transparent conductive film, and ion storage layer are all nano-materials. After redox experiments, the reduction times can be as high as 10,000 to 12,000 times, and the service life is also long.

3. Good light and dark contrast. It can effectively increase the ion conduction speed and shorten the decolorization/coloring time. Under the irradiation of 500nm wavelength in the visible spectrum, the tungsten oxide molybdenum nanowires have a fading penetration rate of 70.2%, a discoloration penetration rate of 43.2%, and a penetration rate change of 27%.

4. The ion-conducting electrolyte layer is a mixture of ionic liquid and a colloidal polymer, which significantly improves the disadvantages of the conventional technology, such as volatilization, exhaustion, spillage, non-environmental protection and short service life of the organic electrolyte.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, several preferred embodiments are specifically cited below and described in detail in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a cross-sectional view of an electrochromic device having a nanometer electrochromic material structure according to the present invention.

Fig. 2 is a perspective view of an electrochromic device having a nanometer electrochromic material structure according to the present invention.

reference sign

1 Electrochromic device with nanometer electrochromic material structure

11 The first transparent substrate

12 transparent conductive layer

13nm electrochromic layer

14 Leading electrolyte layer

15 ion storage layers

16 transparent conductive layer

17 second transparent substrate

Detailed ways

Please refer to Fig. 1 and Fig. 2, the structural representation of the electrochromic device (1) that has the nanometer electrochromic material structure of the present invention, its member mainly comprises: a first transparent substrate (11); a first transparent conductive layer (12); a nanometer electrochromic layer (13); a conduction electrolyte layer (14); an ion storage layer (15); a second transparent conductive layer (16); a second transparent substrate (17 ). Wherein, the first transparent conductive layer (12) is coated on the surface of the first transparent conductive substrate (11) to form a first transparent conductive substrate; the electrochromic layer (13) is coated on the first transparent conductive substrate The surface of the material, the electrochromic layer is composed of a nanowire material; the second transparent conductive layer (16) is coated on the surface of the second transparent substrate (17), forming a second transparent conductive substrate; The ion storage layer (14) is coated on the surface of the second transparent substrate; and the ionizing electrolyte (14) is formed by mixing an ionic liquid and a colloidal polymer, and is filled with the electrochromic Between the first transparent conductive substrate of layer (13) and the second transparent conductive substrate containing the ion storage layer (15).

Wherein, the first transparent substrate (11) and the second transparent substrate (17) are selected from one of glass substrates, plastic substrates or synthetic resin flexible substrates. The difference between its components lies in the different conductive substrates used. If the substrates are all glass, it is a transmissive element, which can be applied to smart windows and filter plates. The amount of light penetration can be determined by the potential of the conductive substrate. If one side of the substrate is transparent conductive glass, and the other side is an opaque substrate with reflective properties, it is a reflective element, which can be applied to rearview mirrors or displays.

The above-mentioned first transparent conductive layer (12) and second transparent conductive layer (16) are indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum zinc oxide (AZO), indium zinc oxide (IZO) , zinc oxide (ZnO), germanium zinc oxide (GZO) or carbon nanotubes.

Indium tin oxide thin film is composed of indium oxide (In ₂ O ₃ ) doped with tin oxide (SnO ₂ ). Generally, ITO has the lowest resistance ratio and the highest light emission when In ₂ O ₃ /SnO ₂ =90/10. Transmittance, the visible light transmittance can reach between 80 and 90%. IZO (Indium Zinc Oxide) is a material composed of In ₂ O ₃ added with 7-10% ZnO. Its advantage is that it can form a film at low temperature. The IZO obtained at room temperature is amorphous and can be etched with weak acid to reduce the wire material. damage, and the surface of the IZO film is smooth, suitable for the production of large-area panels. ZnO is a conductive material composed of the base material, because Zn (zinc) metal is more abundant and cheaper than In (indium), and it is less toxic and easier to etch than ITO. However, due to the high resistance of pure ZnO, when the ambient temperature is higher than 150°C, its electrical stability is not good. In order to obtain low resistance, it can be doped with trace elements such as In, Al, Ga, etc.

The nanowire material of the electrochromic layer 13 is selected from one or a combination of zinc oxide nanowires, tungsten oxide nanowires, molybdenum oxide nanowires or tungsten molybdenum oxide nanowires. The nanowires defined here mean that the two-dimensional dimensions of the structure are between 1 and 100 nanometers, and the length thereof can exceed 100 nanometers. The two-dimensional size of the nanowire material is usually defined as a wire diameter between 1 and 100 nanometers. In an embodiment of the present invention, the diameter of the nanowire material is between 10-100 nm, preferably between 30-60 nm.

It should be noted that, in the present invention, the nanowire material of the electrochromic layer 13 is composed of a metal oxide having a needle-like nanostructure. Wherein, the needle-like nanostructure refers to a structure similar to nanopillars or nanowires, and the diameter width of the pillar or wire structure can gradually become smaller from the bottom end to the top end.

In the present invention, the nanowire material used as the electrochromic layer 13 is preferably composed of nanometer tungsten oxide. However, it should be noted that it is not limited to the nano-tungsten oxide layer. The nanostructured tungsten oxide has a two-dimensional wire diameter between 30nm and 60nm, and is prepared by a sol-gel method. The sol-gel is formed by combining an organometallic compound and a hydrocarbon. In addition, the temperature of the combination of the organometallic compound and the hydrocarbon is between 25°C and 100°C. As the diameter of the acicular structure of acicular tungsten oxide becomes smaller, the specific surface area will increase significantly, that is, the percentage of surface atoms will increase significantly. For a particle with a diameter of 10nm, about 15% of the atomic sites are in the The particle surface, and almost all the atoms on the nanoparticle with a diameter of 1nm are surface atoms. The specific surface area S of the nano-tungsten oxide layer can be increased to more than 80m ² /g, and the electrolyte solution adsorbed on it can be increased, thereby increasing its electronic conductivity, which can reduce the driving voltage required by the electrochromic device, making the electrochromic device The chromic element has the advantages of rapid color changing capability and extended service life. .

Tungsten oxide is by far the most widely studied material, while molybdenum oxide has similar electrochromic properties. Although the color-changing effect of molybdenum oxide is not as good as that of tungsten oxide, the maximum value of light absorbed by molybdenum oxide is closer to visible light when it changes color, and humans are more sensitive to its changes, so there are still many uses. When materials are nanosized, many properties will be enhanced or changed. Among them, the discoloration theory of tungsten and molybdenum oxide:

Positively charged ions (such as H ⁺ or Li ⁺ ) and electrons are injected into MoO ₃ at the same time and absorb light energy to become HMoO ₃ , that is, the electrochemical reaction in which electrons jump from Mo ⁵⁺ to Mo ⁶⁺ . Light produces discoloration effect, simple reaction formula of tungsten oxide and molybdenum oxide:

Mo ⁶⁺ +e-+hv→Mo ⁵⁺

W ⁶⁺ +e-+hv→W ⁵⁺

After combining the oxidation and reduction equations:

W ⁶⁺ (A)+W ⁵⁺ (B)+hv→W ⁵⁺ (A)+W ⁶⁺ (B) Emm

Mo ⁶⁺ (A)+Mo ⁵⁺ (B)+hv→Mo ⁵⁺ (A)+Mo ⁶⁺ (B) Eww

Among them, Emm and Eww are the photon energy absorbed by molybdenum oxide and tungsten oxide when they change color respectively. Now that tungsten oxide and molybdenum oxide are grown together, the material will have two unequal energy level positions Mo ⁶⁺ and W ⁶⁺ , after the ions and electrons are injected into the material at the same time, they will stay on the Mo ⁶⁺ of the lower energy level, and then react, the energy of the Mo ⁶⁺ position in tungsten and molybdenum oxide is less than the energy of the W ⁶⁺ position is ΔE:

EW ⁺⁶ -EMo ⁺⁶ = ΔE

Therefore, the energy (Emw) of electrons transitioning from molybdenum to tungsten will be greater than the energy (Eww) of electrons transitioning in tungsten by ΔE energy.

It can be seen that MoO ₃ -WO ₃ can effectively increase the energy (2.15ev) of light absorbed during discoloration, which is easier to recognize than MoO (1.56ev) and WO ₃ (1.4ev), so it can achieve a better visual discoloration effect. The electrochromic test cycle of an element with an area of 8.0cm×15.0cm exceeds 10,000 times, and the switching time (coloring and decolorization) is less than 245 milliseconds, the coloring efficiency is 265cm ² C ^-1 , and the steady-state current (coloration and decolorization) ) is less than 5uAcm ^-2 , and the memory time exceeds 650 seconds.

The ion-conducting electrolyte layer (14) is composed of an ionic liquid and a colloidal polymer. The ionic liquid is 1M LiClO ₄ of lithium salt, and an ionic liquid mixed with [EMIM][BF ₄ ] (wherein EMIM is ethyl methyl imidazolium ion [ethyl methyl imidazolium]); and the colloidal polymer is changed to poly Vinyl chloride (polyvinylchloride, PVC). Wherein, the ionic conductivity of the formed colloidal polyelectrolyte is about 10 ⁻² S/cm. Among them, when the electrolyte is mixed with the glue, it is directly coated (screen printed) on the glass and then heated and dried to harden. It should be noted that when the electrolyte is mixed with the glue, the glue containing the electrolyte can also be made into a film, cut to an appropriate size and pasted on the glass, and then heated and pressed by a laminator to bond two pieces of glass to obtain similar characteristics. In another implementation, the ionic liquid mixed with [EMIM][BF ₄ ] was changed to [BMIM][TFSI] (where BMIM stands for butylmethyl imidazolium); and the colloidal polymer was changed to poly Vinyl alcohol (Polyvinyl alcohol, PVA). Wherein, the ionic conductivity of the formed colloidal polyelectrolyte is about 3×10 ⁻³ S/cm. Among them, when the electrolyte is mixed with the adhesive material, the adhesive material containing the electrolyte is made into a film, cut to an appropriate size and pasted on the glass, and then heated and pressed by a laminator to bond two pieces of glass.

The ion storage layer (15) is made of nano-nickel oxide film, nano-nickel-iron oxide film and the like. The nano-thin film defined here means that one dimension of its structure is between 1 and 100 nanometers, and generally refers to a thickness between 1 and 100 nanometers. In an embodiment of the present invention, the thickness of the nano-film material is between 1-100 nanometers, preferably between 50-90 nanometers.

A nano-nickel oxide film with a thickness of 80 nm was prepared on a transparent conductive glass by reactive plasma ion sputtering technology, and an external potential was given in an electrolyte of 0.1M LiClO ₄ aqueous solution. When depositing a thin film, when the flow ratio of argon/oxygen into the plasma chamber is 40sccm:10sccm, there is a large change in the transmittance, and the maximum optical density change (Optical density change) ΔOD=0.45, its penetration The transmittance increases with the increase of the number of electrochromic reactions, and tends to be stable gradually. Sputtering time under power supply (150Watt), its ΔOD value is better, and the life of the nano-nickel oxide film prepared under this condition can reach more than thousands of times.

Another way is to use atmospheric pressure plasma to prepare nano-nickel oxide color-changing film. In addition, after adding iron oxide into the nickel oxide film, the electrochemical properties of the nickel oxide film are indeed increased.

In order to make the characteristics of the present invention clearer to those skilled in the art, the electrochromic device with the nanometer electrochromic material structure of the present invention is illustrated with examples.

The embodiment of the transparent conductive layer ( 12 ) ( 16 ) is to use a nano-carbon layer as one of the nano-materials. Take the _SiO2 dispersion (purchased from Changchun Chemical Industry, the dispersed phase is 2-butanone phase (MEK), the content is 15 to 45 wt%, and the average particle size is 10 to 20nm), and then it is coated on the polyethylene surface with a wire rod. On a phthalate (PET) substrate, dry at 78°C. Then take single-walled carbon nanotubes (Single-walled carbon nanotube, SWCNT, purchased from Iljin, commodity model ASP-100F) with a purity of 65 to 75%, and an average tube diameter of 10 nm, sodium dodecylbenzenesulfonate (sodium dedocylbenzene sulfonate) and deionized water were mixed at a weight ratio of 0.2/0.2/100, and dispersed for one hour with a cell pulverizer to form a carbon nanotube dispersion, and then coated on the SiO ₂ layer with a wire rod , drying at 78 ° C to form a nano-carbon layer. The light transmittance of the nanocarbon layer is measured with a wavelength of 500 nm by using an ultraviolet/visible spectrometer (UV/Visible spectrometer). Taking the substrate and the inorganic layer as the background, the light transmittance of the carbon nano-layer in this embodiment is 96.1% after deducting the background value. The nano-carbon layer was measured by a four-point probe resistance meter, and its sheet resistance was 1.37x103Ω.

A preferred embodiment of the nanowires of the electrochromic layer (15) is to use tungsten oxide molybdenum nanowires. Prepared by physical vapor transport method using furnace tube heating: the growth of tungsten trioxide and molybdenum nanowires in the experiment is not a gas-liquid-solid (VLS) growth mechanism, but a gas-solid (VS) growth mechanism. The mechanism is a precedent for using high temperature to make the vapor pressure of the material greater than the pressure of the environment, so that the material is vaporized and driven by gas. When passing through the low temperature zone, the sudden temperature will create an unstable environment, and the material will re-precipitate to form a nanostructure.

First, cut the glass coated with a transparent conductive layer to the required specifications, put it into a container filled with alcohol solution, clean it with an ultrasonic vibration cleaner, take it out, and then blow it dry with a nitrogen gun. Take appropriate tungsten oxide and molybdenum oxide powders and place them on different crucible boats respectively, place molybdenum oxide (99.9%), tungsten oxide (99.9%) and pre-treated nano-carbon glass in the quartz tube, and then lock the stainless steel sleeve Seal the furnace tube. After the furnace tube is sealed, the diffusion pump system is opened to evacuate to 10 ^-6 torr, and then the process gas flow is introduced to grow nano-tungsten oxide molybdenum nanowires.

The ion-conducting electrolyte layer (14) uses 1M LiClO ₄ of lithium salt, and an ionic liquid mixed with [EMIM][BF4] (wherein EMIM is ethyl methyl imidazolium ion [ethyl methyl imidazolium]); and the colloidal polymer The product is ethylene vinyl acetate copolymer (Ethylene vinyl acetate copolymer, EVA). The electrolyte is injected into the electrochromic device with nanometer tungsten and molybdenum nanowires prepared above. Wherein, the ionic conductivity of the formed colloidal polymer electrolyte is about 10 ⁻³ S/cm at room temperature. Among them, when the electrolyte is mixed with the glue, it is directly coated (screen printed) on the glass and then heated and dried to harden. Since the above-mentioned gel electrolyte is used, there is no problem of leakage or volatilization of the electrolyte.

The ion storage layer (13) adopts a highly stable water-based crystalline nickel oxide sol solution, the nickel oxide nanoparticles have a particle size of 10-30nm and a solid content of 0.1-2.0%. On the material, a nanometer film is formed by baking. The preparation method of nano-nickel oxide particles can be prepared by liquid phase method: for example, from the precursor of nickel nitrate [Ni(NO ₃ ) ₂ 6H ₂ O], adding ammonia water and stirring continuously until the solution reaches pH=7, the green hydroxide Nickel [Ni(OH) ₂ ] powder (LP1) can be heated to obtain nano-nickel oxide particles.

The electrochromic device according to the present invention has the following effects:

1. The driving voltage of the electrochromic device is between 1 volt and 4 volts. Compared with the general driving voltage of 40 volts to 80 volts, there is a large and obvious gap, which can achieve the function of reducing the operating voltage and saving energy.

2. High redox times and long service life. The electrochromic layer, the transparent conductive film, and the ion storage layer can all be nanomaterials. After redox experiments, the reduction times can be as high as 10,000 to 12,000 times, and the service life is longer.

3. Good light and dark contrast. It can effectively increase the ion conduction speed and shorten the decolorization/coloring time. Under the irradiation of 500nm wavelength in the visible spectrum, the tungsten oxide molybdenum nanowires have a fading penetration rate of 70.2%, a discoloration penetration rate of 43.2%, and a penetration rate change of 27%.

Although the present invention can be embodied in different forms, the content shown in the drawings and the content described above are preferred embodiments of the present invention, and please understand that the content disclosed herein is considered as the present invention and are not intended to limit the invention to the particular embodiments shown and/or described.

Claims (9)

1. the electrochromic device with nanometer electrochromic material structure is characterized in that, comprising:

One first transparent base, its upper surface have one first transparency conducting layer;

One electrochromic layer is formed on this first transparency conducting layer of this first transparent base, and this electrochromic layer is made up of a nano-material;

One diversion dielectric substrate is formed on this electrochromic layer;

One ion storage layer is formed on this dielectric substrate, and this ion storage layer is made up of a nano film material; And

One second transparent base, surface thereof are provided with one second transparency conducting layer, and this second transparency conducting layer is folded between this ion storage layer and this second transparent base;

Wherein this nano-material in this electrochromic layer is the combination that is selected from one of zinc oxide nanowire, tungsten oxide nano, molybdena nano wire or oxidation tungsten nano wire or its many persons.

2. the electrochromic device with nanometer electrochromic material structure according to claim 1, it is characterized in that this first transparency conducting layer and second transparency conducting layer are to be selected from one of tin indium oxide (ITO), fluorine doped tin oxide (FTO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), zinc paste (ZnO), germanium oxide zinc (GZO) or CNT.

3. the electrochromic device with nanometer electrochromic material structure according to claim 1 is characterized in that, the line of this nano-material in this electrochromic layer directly is between 30 to 60 nanometers.

4. the electrochromic device with nanometer electrochromic material structure according to claim 1 is characterized in that, this nano-material in this electrochromic layer is tungsten oxide nano.

5. the electrochromic device with nanometer electrochromic material structure according to claim 1 is characterized in that, this nano-material in this electrochromic layer is oxidation tungsten nano wire.

6. the electrochromic device with nanometer electrochromic material structure according to claim 1 is characterized in that, this diversion dielectric substrate is mixed by an ionic liquid and a gum polymers.

7. the electrochromic device with nanometer electrochromic material structure according to claim 1 is characterized in that, this nano film material of this ion storage layer is for being selected from one of nano-nickel oxide film and nano-nickel oxide iron thin film.

8. the electrochromic device with nanometer electrochromic material structure according to claim 6, it is characterized in that, the gum polymers of this diversion dielectric substrate is to be selected from polymethylmethacrylate (polymethyl methacrylate, PMMA), polyvinylidene fluoride (polyvinylidene difluoride, PVDF), Polyvinylchloride (polyvinyl chloride, PVC), polyoxyethylene (polyethylene oxide, PEO) and poly hydroxy ethyl acrylate (polyhydroxyethyl methacrylate, PHEMA), Ethylene vinyl accetate copolymer (Ethylene vinyl accetate copolymer, EVA), one of polyvinyl alcohol (PVA) (Polyvinyl alcohol, PVA).

9. the electrochromic device with nanometer electrochromic material structure according to claim 7 is characterized in that, this nano film material of this ion storage layer is the nano-nickel oxide film.

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