JP7639687B2 - Light emitting/receiving element, electronic device using same, and biosensing device - Google Patents

Description

The present invention relates to a light receiving/emitting element having both a function as a light receiving element and a function as a light emitting element, and to an electronic device and a biosensing device using the same.

In recent years, the Internet of Things (IoT) and big data have been attracting attention, and the importance of sensing technology to acquire various data that supports them is increasing. There are various sensing techniques, but optical sensing is one of the most useful sensing techniques because it can be used in a variety of applications, such as changing the target wavelength to change the sensing target.

Optical sensors generally have a light-emitting element and a light-receiving element, and sense an object by irradiating the object with light from the light-emitting element and receiving the light that is transmitted through or reflected by the object with the light-receiving element. Such optical sensors can read biological information, for example, by using near-infrared light as a wavelength. Furthermore, by forming the substrate, light-emitting element, and light-receiving element mainly from organic materials, it is possible to configure a thin and flexible device (see, for example, Non-Patent Document 1).

In addition, these light-emitting elements and light-receiving elements can be arranged in a large number on a substrate to form an array, and can be used as an imaging device. For example, Non-Patent Document 2 discloses a flexible imaging device capable of reading biological information, in which an organic light-receiving element is arranged on a thin transistor array (TFT array) substrate. However, since this device does not incorporate a light-emitting element, a separate light source from the outside is required. In addition, Patent Document 1 discloses an integrated light-receiving and receiving device in which a plurality of light-emitting elements and a plurality of light-receiving elements are arranged in a large number independently on a substrate. In the device described in Patent Document 1, by making it an integrated light-receiving and receiving type, an external light source is not required, and a thinner and more flexible device can be configured. However, in this way, it takes a lot of time and effort to separately produce a large number of light-emitting elements and a plurality of light-receiving elements on a substrate, and depending on the manufacturing method, there is a limit to reducing the area of one element. Furthermore, since the light-emitting elements and the light-receiving elements are separately produced on the same substrate, the light-receiving area for sensing within the substrate is reduced, and there is a limit to high definition.

On the other hand, Patent Document 2 discloses an imaging element having both a light receiving function and a light emitting function. By using an element having both a light receiving function and a light emitting function, it is not necessary to separately manufacture a light emitting element and a light receiving element, and manufacturing becomes easier. Furthermore, as an element having such functions, an element in which rubrene and fullerene are laminated, and an element in which a triphenylamine compound and fullerene are laminated have also been proposed (for example, see Non-Patent Documents 3 and 4). Also, an element in which a small amount of rubrene is added to a mixed layer of polythiophene and a fullerene derivative has been proposed (for example, see Non-Patent Document 5).

"Science Advances", 2016, Vol. 2, p. e1501856 Nature Electronics, 2020, Vol. 3, pp. 113-121 "Advanced Materials", 2007, Vol. 19, pp. 3613-3617 "Advanced Materials", 2006, Vol. 18, pp. 3033-3037 "Synthetic Metals", 2012, Vol. 162, pp. 281-284

JP 2013-73965 A JP 2009-81297 A

The inventors of the present invention considered that an element having both a light receiving function and a light emitting function (hereinafter referred to as a light receiving/emitting element) would enable a thin and flexible light sensing device to be configured without the need for an external light source, and would be applicable to a variety of uses. However, the light receiving/emitting elements proposed so far have had insufficient light receiving sensitivity to light emitted from a light receiving/emitting element of the same configuration.

The present invention has been made in consideration of the above circumstances, and aims to provide an optical element having good light receiving sensitivity to light emitted from an optical element of the same configuration, and an electronic device and a biosensing device using the same.

As a result of repeated investigations, the present inventors have found that the overlap between the light receiving sensitivity spectrum and the emission spectrum of the light receiving/emitting element is particularly important. That is, in order to solve the above-mentioned problems and achieve the object, the light receiving/emitting element according to the present invention includes an anode, a cathode, and an light receiving/emitting layer located between the anode and the cathode and made of two or more organic materials, the light receiving/emitting layer contains an electron donating material and an electron accepting material that satisfy the energy level relationship represented by the following formulas (1) and (2), at least one of the electron donating material and the electron accepting material is a light receiving/emitting layer material having a band gap smaller than the maximum light emission wavelength energy when a voltage is applied to the light receiving/emitting layer, the electron donating material is unevenly distributed on the anode side in the light receiving/emitting layer, and the overlapping region between the normalized light receiving sensitivity spectrum and the normalized emission spectrum occupies 50% or more of the region of the normalized emission spectrum.
HOMO of electron donor material>HOMO of electron acceptor material (1)
LUMO of electron donor material>LUMO of electron acceptor material (2)

In addition, the light receiving/emitting element of the present invention is characterized in that, in the above-mentioned invention, the overlapping area between the light receiving sensitivity spectrum before normalization and the normalized emission spectrum occupies 5% or more of the area of the normalized emission spectrum.

In addition, the light-emitting/receiving element according to the present invention is characterized in that, in the above-mentioned invention, the electron-donating material is the light-emitting/receiving layer material having a band gap smaller than the maximum emission wavelength energy when a voltage is applied to the light-emitting/receiving layer.

Moreover, in the above-mentioned light receiving/emitting device according to the present invention, the light receiving/emitting layer has an absorbance of 0.1 or more at a maximum emission wavelength when a voltage is applied to the light receiving/emitting layer.

In addition, the light emitting/receiving element according to the present invention is characterized in that, in the above-mentioned invention, the absorption coefficient of a single film of the light emitting/receiving layer material is 30,000 ^{cm or} more at the maximum emission wavelength when a voltage is applied to the light emitting/receiving layer.

In addition, the light emitting/receiving element according to the present invention is characterized in that, in the above-mentioned invention, the light emitting/receiving layer has at least one of a light receiving portion and a light emitting portion having a domain size of 40 nm or more.

In addition, the light emitting/receiving element according to the present invention is characterized in that, in the above-mentioned invention, a maximum emission wavelength when a voltage is applied to the light emitting/receiving layer is 700 nm or more.

In addition, the light emitting/receiving device according to the present invention is characterized in that, in the above-mentioned invention, the light emitting/receiving layer contains a diketopyrrolopyrrole boron complex compound and a fullerene compound.

In addition, the light emitting/receiving device according to the present invention is characterized in that, in the above-mentioned invention, the light emitting/receiving layer contains a rubrene compound and a thiophene compound.

An electronic device according to the present invention is characterized in that it comprises a plurality of light emitting/receiving elements according to any one of the above aspects of the invention on a substrate.

In addition, in the electronic device according to the present invention, the plurality of light emitting/receiving elements have the same configuration.

In addition, the electronic device of the present invention comprises a plurality of light-receiving and light-emitting elements described in any one of the above inventions, the plurality of light-receiving and light-emitting elements being of identical configuration to one another, and at least one first light-receiving and light-emitting element among the plurality of light-receiving and light-emitting elements emits light to irradiate an object, and a second light-receiving and light-emitting element other than the first light-receiving and light-emitting element receives light that is transmitted through or reflected by the object.

Further, an electronic device according to the present invention is characterized in that it comprises the light emitting/receiving element according to any one of the above aspects of the invention on a TFT array substrate.

A biological sensing device according to the present invention is characterized by comprising the light receiving and emitting element according to any one of the above aspects of the present invention.

According to the present invention, it is possible to provide an optical detector that is easy to manufacture and has good optical sensitivity to light emitted from optical detectors of the same configuration, and an electronic device and a biosensing device using the same.

FIG. 1 is a diagram showing an example of a normalized light receiving sensitivity spectrum and a normalized light emission spectrum of a light receiving/emitting element according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a light receiving sensitivity spectrum (external quantum yield spectrum) before normalization and a normalized emission spectrum of the light receiving and emitting element according to the embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing one aspect of a light emitting/receiving element according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of a pulse wave measurement result obtained by the biosensing device produced in Example 13. FIG. 5 is a diagram showing an example of a pulse wave measurement result obtained by the biosensing device produced in Example 14. FIG. 6 is a diagram showing an example of a pulse wave measurement result obtained by the biosensing device produced in Comparative Example 6.

The following is a detailed description of embodiments of the light-receiving and light-emitting element according to the present invention, and an electronic device and a biosensing device using the same, but the present invention is not limited to the following embodiments and can be modified in various ways depending on the purpose and application. It should be noted that the drawings are schematic, and the dimensional relationships between the elements, the ratios between the elements, and the like may differ from the actual ones.

(Light emitting/receiving element)
The light emitting/receiving device according to the embodiment of the present invention includes an anode and a cathode, and a light emitting/receiving layer made of two or more organic materials between the anode and the cathode. In this light emitting/receiving device, the light emitting/receiving layer is a layer that exhibits a light emitting function when a positive voltage is applied to the anode, and exhibits a light receiving function when a zero or negative voltage is applied to the anode. In addition, it is preferable that at least one of the anode and the cathode is optically transparent.

The light receiving/emitting element according to the embodiment of the present invention satisfies the condition that "the overlapping area between the normalized light receiving sensitivity spectrum and the normalized emission spectrum (hereinafter, appropriately abbreviated as overlapping area) occupies 50% or more of the area of the normalized emission spectrum". FIG. 1 is a diagram showing an example of the normalized light receiving sensitivity spectrum and the normalized emission spectrum of the light receiving/emitting element according to the embodiment of the present invention. For example, as shown in FIG. 1, the normalized light receiving sensitivity spectrum 101 is in a state where it partially overlaps with the normalized emission spectrum 102. The overlapping area 103 between the normalized light receiving sensitivity spectrum 101 and the normalized emission spectrum 102 occupies 50% or more of the area of the normalized emission spectrum 102. In other words, the ratio of the overlapping area 103 to the entire area of the normalized emission spectrum 102 is 50% or more. By setting the overlap between the two spectra in this way, the light receiving/emitting element can achieve high light receiving sensitivity to light emitted from a light receiving/emitting element having the same configuration as the light receiving/emitting element.

In the present invention, the light receiving sensitivity spectrum is a spectrum showing the photoelectric conversion response in terms of external quantum yield when the light receiving/emitting element is irradiated with light of each wavelength. The normalized light receiving sensitivity spectrum is obtained by normalizing the light receiving sensitivity spectrum using a method described below. The normalized emission spectrum is obtained by normalizing the emission spectrum of the light receiving/emitting element using a method described below. In addition, in FIG. 1, the normalized light receiving sensitivity is a normalized value of the light receiving sensitivity indicated by the normalized light receiving sensitivity spectrum. The normalized emission intensity is a normalized value of the emission intensity indicated by the normalized emission spectrum.

Further, it is more preferable that the light receiving/emitting element according to the embodiment of the present invention satisfies the condition that "the overlapping area between the light receiving sensitivity spectrum before normalization and the normalized emission spectrum occupies 5% or more of the area of the normalized emission spectrum". FIG. 2 is a diagram showing an example of the light receiving sensitivity spectrum before normalization and the normalized emission spectrum of the light receiving/emitting element according to the embodiment of the present invention. For example, as shown in FIG. 2, the light receiving sensitivity spectrum 101A before normalization is in a state where it is partially overlapped with the normalized emission spectrum 102. It is preferable that the overlapping area 103A between the light receiving sensitivity spectrum 101A before normalization and the normalized emission spectrum 102 occupies 5% or more of the area of the normalized emission spectrum 102. That is, the ratio of the overlapping area 103A to the entire area of the normalized emission spectrum 102 is preferably 5% or more. The ratio of the overlapping area 103A is more preferably 10% or more. This can further increase the light receiving sensitivity of the light receiving/emitting element to the light emitted from the light receiving/emitting element itself. The light receiving sensitivity spectrum before normalization is the light receiving sensitivity spectrum of the light receiving/emitting element before normalization (that is, the light receiving sensitivity spectrum is not normalized).

The light receiving sensitivity spectrum can be measured by a spectral sensitivity measuring device. For example, the current response when monochromatic light is irradiated to the light receiving/emitting element is measured by a spectral sensitivity measuring device, and the photoelectric conversion response is converted into an external quantum yield, so that the desired light receiving sensitivity spectrum can be displayed. The light receiving sensitivity spectrum can be normalized by dividing the external quantum yield of each wavelength by the maximum value of the wavelength dependency of the external quantum yield obtained as described above. The emission spectrum can be obtained by measuring the amount of light emitted at each wavelength using a spectroradiometer. The emission spectrum can be normalized by dividing the amount of light emitted at each wavelength by the maximum value of the wavelength dependency of the amount of light emitted obtained as described above.

Furthermore, in the light receiving/emitting element according to the embodiment of the present invention, the absorbance of the light receiving/emitting element at the maximum emission wavelength when a voltage is applied to the light receiving/emitting layer is preferably 0.1 or more. By making this absorbance 0.1 or more, the light receiving sensitivity to the light emitted from the light receiving/emitting element itself can be further increased. Here, the absorbance of the light receiving/emitting element is obtained by measuring the reflection/absorption spectrum of the light receiving/emitting element. At this time, the minimum absorbance of the light receiving/emitting element measured in the wavelength range of 300 nm to 1200 nm is used as a baseline for correction, and the difference between the reflection/absorption spectrum of the light receiving/emitting element actually measured and the baseline value (minimum absorbance) is the target absorbance. The maximum emission wavelength is the wavelength at which the amount of light emitted (light emission intensity) in the emission spectrum reaches its maximum peak.

In this way, by achieving high light receiving sensitivity to light emitted from light receiving and emitting elements of the same configuration, it becomes unnecessary to manufacture separate light receiving elements and light emitting elements, and it becomes possible to realize a light receiving and emitting element that is easy to manufacture and has both a light receiving function and a light emitting function. By using such a light receiving and emitting element, it becomes possible to realize an optical sensor that can enjoy the effects of the light receiving and emitting element.

In addition, in the light receiving/emitting element according to the embodiment of the present invention, the maximum emission wavelength when a voltage is applied to the light receiving/emitting layer is preferably 700 nm or more (i.e., a wavelength in the infrared light wavelength region). By having a maximum emission wavelength in such an infrared light wavelength region, an optical sensor using the light receiving/emitting element can operate by receiving and emitting light that is invisible to the human eye. In addition, the wavelength range of 700 nm to 1400 nm is a region called a biological window. The light receiving/emitting element according to the embodiment of the present invention can be suitably applied to biological sensing by having light receiving/emitting responsiveness in this wavelength range. The sharper the shape of the emission spectrum, the greater the overlap with the light receiving sensitivity spectrum, which is easily broadened. For this reason, the half-width of the emission spectrum is preferably narrower. In addition, in order to select the sensing target according to the wavelength, the half-width of the emission spectrum is preferably narrower. Specifically, the half-width of the emission spectrum is preferably 60 nm or less.

Fig. 3 is a schematic cross-sectional view showing one aspect of a light-emitting/receiving element according to an embodiment of the present invention. As shown in Fig. 3, the light-emitting/receiving element 10 according to this embodiment includes an anode 2, a cathode 6, and a light-emitting/receiving layer 4 located between the anode 2 and the cathode 6 on a substrate 1. The light-emitting/receiving element 10 also includes a hole transport layer 3 located between the anode 2 and the light-emitting/receiving layer 4, and an electron transport layer 5 located between the cathode 6 and the light-emitting/receiving layer 4. For example, the light-emitting/receiving element 10 shown in Fig. 3 includes an anode 2, a hole transport layer 3, a light-emitting/receiving layer 4, an electron transport layer 5, and a cathode 6 on a substrate 1 in this order.

The light emitting/receiving device 10 is not limited to the laminated structure shown in Fig. 3. Although not particularly shown, for example, as another embodiment of the light emitting/receiving device 10, the light emitting/receiving device may have a cathode 6, an electron transport layer 5, a light emitting/receiving layer 4, a hole transport layer 3, and an anode 2 on a substrate 1 in this order.

In order for the light emitting/receiving element 10 to emit and receive light, it is preferable that either the anode 2 or the cathode 6 has optical transparency. Of these electrodes, the one having optical transparency may be the electrode on the substrate 1 side (anode 2 in FIG. 3 ) or the electrode on the opposite side to the substrate 1 (cathode 6 in FIG. 3 ).

The substrate 1 is a substrate on which an electrode material or an organic semiconductor layer can be laminated depending on the type and application. For example, a film or plate made of an inorganic or organic material by any method can be used as the substrate 1. Examples of inorganic materials constituting the substrate 1 include non-alkali glass, quartz glass, alloys such as aluminum, iron, copper, and stainless steel. Examples of organic materials constituting the substrate 1 include polyester, polycarbonate, polyolefin, polyamide, polyimide, polyphenylene sulfide, polyparaxylene polymethyl methacrylate, epoxy resin, and fluorine-based resin. In addition, when the light receiving/emitting element 10 emits or receives light from the substrate 1 side, it is preferable that the film or plate used as the substrate 1 has a light transmittance of about 80%. In addition, when a large number of light receiving/emitting elements 10 are arranged and used, it is preferable that the substrate 1 is combined with a TFT array (TFT array substrate). Forming a TFT array on the substrate 1 is also one of the preferable aspects.

The anode 2 and the cathode 6 (hereinafter, these are collectively referred to as "electrodes") are made of a conductive material. For example, as the material of the electrodes, in addition to metals such as gold, platinum, silver, copper, iron, zinc, tin, aluminum, indium, chromium, nickel, cobalt, scandium, vanadium, yttrium, cerium, samarium, europium, terbium, ytterbium, molybdenum, tungsten, and titanium, metal oxides, composite metal oxides (indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), etc.), alkali metals, and alkaline earth metals (lithium, magnesium, sodium, potassium, calcium, strontium, barium), etc. are preferably used. Furthermore, electrodes made of alloys of these metals or laminates of these metals are also preferably used. In addition, electrodes containing graphite, graphite intercalation compounds, carbon nanotubes, graphene, polyaniline and its derivatives, and polythiophene and its derivatives are also preferably used. The electrode may be a mixed layer made of two or more materials, or may be a layer having a laminate structure in which a plurality of layers made of two or more compounds are laminated.

In addition, at least one of the anode 2 and the cathode 6 is preferably light-transmitting. In the present invention, it is sufficient that either the anode 2 or the cathode 6 is light-transmitting, but both the anode 2 and the cathode 6 may be light-transmitting. Here, "having light-transmitting properties" means "transmitting light to such an extent that incident light reaches the light-receiving/emitting layer to generate electromotive force, and that light generated by applying a voltage to the light-receiving/emitting layer is extracted to the outside". In other words, when an electrode has a light transmittance value exceeding 0%, the electrode is light-transmitting. The light-transmitting electrode preferably has a light transmittance of 60% to 100% in all wavelength regions from 400 nm to 900 nm. The thickness of the light-transmitting electrode may be a thickness that provides sufficient electrical conductivity, and is preferably 20 nm to 300 nm, although it varies depending on the material. In addition, the electrode that does not have light-transmitting properties is sufficient as long as it is electrically conductive, and the thickness is not particularly limited.

The hole transport layer 3 is not an essential component of the light emitting/receiving element of the present invention. However, by providing the hole transport layer 3, it is possible to form an interface state suitable for extracting or injecting carriers, and it is also effective in preventing short circuits between electrodes. Therefore, in the present invention, it is preferable that the light emitting/receiving element is provided with the hole transport layer 3. For example, the light emitting/receiving element 10 shown in FIG. 3 includes the hole transport layer 3 between the anode 2 and the light emitting/receiving layer 4.

Examples of materials for forming the hole transport layer 3 include conductive polymers such as polythiophene polymers, poly-p-phenylene vinylene polymers, polyfluorene polymers, polypyrrole polymers, polyaniline polymers, polyfuran polymers, polypyridine polymers, and polycarbazole polymers; low-molecular-weight organic compounds exhibiting p-type semiconductor characteristics, such as phthalocyanine derivatives (H ₂ Pc, CuPc, ZnPc, and the like), porphyrin derivatives, and acene compounds (tetracene, pentacene, and the like); carbon compounds such as carbon nanotubes, graphene, and graphene oxide; molybdenum oxides (MoO _x ) such as MoO ₃ ; tungsten oxides (WO _x ) such as WO ₃ ; nickel oxides (NiO _x ) such as NiO; vanadium oxides (VO _x ) such as V ₂ O ₅ ; zirconium oxides (ZrO _x ) such as ZrO ₂ ; copper oxides (CuO _x ) such as Cu ₂ O; copper iodide; and RuO. _Ruthenium oxides (RuO _x ) such as _{Re 2} O ₇ ,
In particular, polythiophene-based polymers such as polyethylenedioxythiophene (PEDOT) and PEDOT with polystyrene sulfonate (PSS), molybdenum oxide, vanadium oxide, and tungsten oxide are preferably used as materials for the hole transport layer 3. The hole transport layer 3 may be a layer made of a single compound, a mixed layer made of two or more compounds, or a layer having a laminate structure in which a plurality of layers made of two or more compounds are laminated.

When a configuration in which the anode 2 adjacent to the hole transport layer 3 has optical transparency is applied to the light receiving/emitting element 10, the hole transport layer 3 preferably has high optical transparency to the emission wavelength when a voltage is applied to the light receiving/emitting element 10 (specifically, the light receiving/emitting layer 4). That is, in this case, it is more preferable that the material of the hole transport layer 3 is a material that does not have optical absorption ability for the above-mentioned emission wavelength. In addition, the thickness of the hole transport layer 3 is not particularly limited, but is preferably 5 nm or more and 600 nm or less, and more preferably 10 nm or more and 200 nm or less.

The light-receiving/emitting layer 4 is formed between the anode 2 and the cathode 6. For example, in the light-receiving/emitting device 10 shown in Fig. 3, the light-receiving/emitting layer 4 is formed between the hole transport layer 3 on the anode 2 side and the electron transport layer 5 on the cathode 6 side. A voltage is applied to the light-receiving/emitting layer 4 by applying a positive voltage to the anode 2. The light-receiving/emitting layer 4 is a layer that exhibits a light-emitting function when a positive voltage is applied in this manner, and exhibits a light-receiving function when a zero or negative voltage is applied to the anode 2.

The light-receiving and light-emitting layer 4 has the above-mentioned light-emitting and light-receiving functions, and is made of two or more organic materials. The organic materials refer to polymeric and low-molecular-weight materials, and also include complexes that contain metal atoms as part of their chemical structure. The light-receiving and light-emitting layer 4 also contains an electron-donating material and an electron-accepting material. The inclusion of these materials in the light-receiving and light-emitting layer 4 promotes charge separation when the light-receiving and light-emitting layer 4 receives light, and the light-receiving sensitivity of the light-receiving and light-emitting layer 4 can be increased. These electron-donating and electron-accepting materials satisfy the energy level relationships represented by the following formulas (1) and (2).
HOMO of electron donor material>HOMO of electron acceptor material (1)
LUMO of electron donor material>LUMO of electron acceptor material (2)
In formula (1) and formula (2), HOMO is the energy level of the highest occupied molecular orbital, and LUMO is the energy level of the lowest unoccupied molecular orbital.

In addition, it is preferable that the energy level difference between the electron donor material and the electron acceptor material satisfies the following formulas (3) and (4).
HOMO of electron donor material−HOMO of electron acceptor material>0.5 eV (3)
LUMO of electron donating material−LUMO of electron accepting material>0.5 eV (4) From the viewpoint of obtaining a high open circuit voltage, it is preferable that the energy level difference between the electron donating material and the electron accepting material satisfies the following formula (5).
HOMO of electron donating material−LUMO of electron accepting material>1.0 eV (5)

At least one of the electron donating material and the electron accepting material contained in the light emitting and receiving layer 4 is a material (hereinafter referred to as the light emitting and receiving layer material) having a band gap smaller than the maximum light emission wavelength energy when a voltage is applied to the light emitting and receiving layer 4. When the light emitting and receiving layer 4 contains such a material, the proportion of the overlapping region between the above-mentioned normalized light receiving sensitivity spectrum and the normalized emission spectrum to the entire region of the normalized emission spectrum can be easily increased to 50% or more.

Furthermore, inside the light-receiving and light-emitting layer 4, the above-mentioned electron-donating material is unevenly distributed on the anode 2 side. When the light-receiving and light-emitting layer 4 has an asymmetrical configuration as described above with respect to the electron-donating material, the light-receiving and light-emitting layer 4 can improve the charge transportability and the light-receiving sensitivity, and can also improve the recombination property and the light-emitting intensity by the charge blocking. Here, "unevenly distributed on the anode side" refers to a higher concentration on the anode side than on the cathode side in the distribution in the thickness direction of the light-receiving and light-emitting layer. Specifically, the concentration (e.g., the concentration of the electron-donating material) in the region on the anode 2 side of the center position in the thickness direction of the light-receiving and light-emitting layer 4 is higher than that in the region on the cathode 6 side of the center position in the thickness direction of the light-receiving and light-emitting layer 4. Examples of such a configuration include a laminated structure of an electron-donating material and an electron-accepting material, and a laminated structure including a mixed layer of the electron-donating material and the electron-accepting material. Conversely, if the electron-donating material is unevenly distributed on the cathode 6 side inside the light-receiving and light-emitting layer 4, charge injection into the light-receiving and light-emitting layer 4 becomes difficult, and furthermore, the charge blocking effect cannot be obtained, resulting in a decrease in luminescence intensity. Furthermore, when a light-receiving function is to be used, uneven distribution of the electron-donating material on the cathode 6 side also causes a decrease in light-receiving sensitivity, since electrons generated inside the light-receiving and light-emitting layer 4 are difficult to move through the electron-donating material.

Of the electron donating material and electron accepting material contained in the light emitting/receiving layer 4, the electron donating material is preferably a light emitting/receiving layer material having a band gap smaller than the maximum light emission wavelength energy when a voltage is applied to the light emitting/receiving layer 4. Organic materials tend to exhibit p-type semiconductivity due to the influence of various external factors (oxygen, etc.), that is, they are suitable as electron donating materials. Therefore, it is easier to obtain higher light receiving sensitivity when an electron donating material is used as the light emitting/receiving layer material than when an electron accepting material is used as the light emitting/receiving layer material.

The light-receiving and light-emitting layer 4 may contain materials other than those mentioned above. The materials may form a single material layer or a mixed layer inside the light-receiving and light-emitting layer 4. An example of a single material layer or a mixed layer made of the materials is a light-emitting layer in which a host material is mixed with a light-emitting dopant material. The thickness of the light-receiving and light-emitting layer 4 is not particularly limited, but is preferably 30 nm or more and 1000 nm or less, and more preferably 40 nm or more and 1000 nm or less.

Furthermore, it is preferable that the light-receiving and light-emitting layer 4 has at least one of a light-receiving portion and a light-emitting portion with a domain size of 40 nm or more. When the light-receiving and light-emitting layer 4 is a single-material layer, if the thickness is sufficiently smaller than the length (width or depth, etc.) of the light-receiving and light-emitting layer 4 in the planar direction, the average thickness of the light-receiving and light-emitting layer 4 is the average domain size of the single-composition portion in the light-receiving and light-emitting layer 4. Although the reason why the above configuration enhances the light-emitting function of the light-receiving and light-emitting layer 4 is not clear, it is thought that the light-emitting function of the light-receiving and light-emitting layer 4 is enhanced because the excitons of the light-emitting material can be trapped and non-radiative deactivation can be suppressed.

In addition, from the viewpoints of controllability of the emission wavelength and reception wavelength of the light receiving/emitting layer 4, adaptability to flexible light receiving/emitting element 10, and charge transportability, it is preferable that 90% or more of the light receiving/emitting layer 4 is an organic semiconductor.

Furthermore, regardless of the configuration, the light-emitting/receiving layer 4 contains a light-emitting material in any of its layers. The light-emitting material may form a single material layer in the light-emitting/receiving layer 4, or a mixed layer in which a host material is mixed with a light-emitting dopant material as described above may be formed in the light-emitting/receiving layer 4. If the light-emitting material corresponds to the above-mentioned electron-donating material, it may form a mixed layer with an electron-accepting material in the light-emitting/receiving layer 4. If the light-emitting material corresponds to the above-mentioned electron-accepting material, it may form a mixed layer with an electron-donating material in the light-emitting/receiving layer 4.

The light receiving/emitting layer material having a band gap smaller than the maximum light emission wavelength energy preferably has an absorption coefficient of 30000 cm ⁻¹ or more at the maximum light emission wavelength when a voltage is applied to the light receiving/emitting layer 4. The absorption coefficient is more preferably 50000 cm ⁻¹ or more, and even more preferably 90000 cm ⁻¹ or more. By using such a light receiving/emitting layer material, the light receiving sensitivity of the light receiving/emitting element 10 can be further increased. The light receiving/emitting layer material may be a light emitting material or a material other than the light emitting material. When the light receiving/emitting layer material is a light emitting material, the light emitting material is preferably a material with a small Stokes shift. By using a material with a sufficiently small Stokes shift as the light receiving/emitting layer material, it is possible to easily provide the light receiving/emitting layer 4 with both light emitting and light receiving functions. The maximum light emission wavelength energy is the light emission energy at the maximum light emission wavelength, and is expressed by the following formula using the Planck constant h and the speed of light c when the maximum light emission wavelength energy is E _max and the maximum light emission wavelength is λ _max .
_Emax = h × c / _λmax

Examples of materials for forming the light emitting and receiving layer 4 include conductive polymers such as polythiophene polymers, poly-p-phenylenevinylene polymers, polyfluorene polymers, polypyrrole polymers, polyaniline polymers, polyfuran polymers, polypyridine polymers, and polycarbazole polymers; low molecular weight organic compounds exhibiting p-type semiconductor properties, such as phthalocyanine derivatives (H2Pc, CuPc, ZnPc, etc.), porphyrin derivatives, and acene compounds (tetracene, pentacene, etc.); and electron accepting organic materials ( Examples of the material include organic materials exhibiting n-type semiconductor properties such as NTCDA, PTCDA, PTCDI-C8H, oxazole derivatives, triazole derivatives, phenanthroline derivatives, phosphine oxide derivatives, phosphine sulfide derivatives, quinoline derivatives, fullerene compounds, CNT, CN-PPV, IEICO, ITIC, Y6, etc., and light-emitting materials such as rubrene, quinacridone compounds, coumarin compounds, pyrromethene compounds, diketopyrrolopyrrole compounds, and diketopyrrolopyrrole boron complex compounds. The material for forming the light-receiving and light-emitting layer 4 is not limited to these examples, and may be appropriately selected and combined from organic semiconductors and light-emitting materials according to the desired light emission wavelength and light-receiving wavelength.

Among these, a diketopyrrolopyrrole boron complex compound has a small Stokes shift and is an effective material for imparting both light emitting and light receiving functions to the light receiving and emitting layer 4. Furthermore, since a diketopyrrolopyrrole boron complex compound has an emission wavelength of 700 nm or more, it is one of the preferable materials to be contained in the light receiving and emitting layer 4 in order to make the maximum emission wavelength 700 nm or more when a voltage is applied to the light receiving and emitting layer 4. Furthermore, in order to make the diketopyrrolopyrrole boron complex compound function as an electron donating material, a combination of a diketopyrrolopyrrole boron complex compound and a fullerene compound is also one of the preferable embodiments of the material to be contained in the light receiving and emitting layer 4.

In addition to the combination of the diketopyrrolopyrrole boron complex compound and the fullerene compound, a combination of a rubrene compound that emits light in the visible light region and a thiophene compound that has high light absorption in the visible light region is also one of the preferred embodiments of the materials contained in the light-receiving and light-emitting layer 4.

Specific examples of the structure of the diketopyrrolopyrrole boron complex compound include the following compounds described in the non-patent document "Scientific Reports", 2016, Vol. 6, p. 34096.

Specific examples of fullerene compounds include unsubstituted fullerenes such as _C60 fullerene, _C70 fullerene, _C76 fullerene, _C78 fullerene, _C82 fullerene, _C84 fullerene, _C90 fullerene, and _C94 fullerene, and substituted derivatives such as [6,6]-phenyl-C61-butyric acid methyl ester ([6,6]-C61-PCBM or [60]PCBM), [5,6]-phenyl-C61-butyric acid methyl ester, [6,6]-phenyl-C61-butyric acid hexyl ester, [6,6]-phenyl-C61-butyric acid dodecyl ester, and phenyl-C71-butyric acid methyl ester ([70]PCBM). Of these, _C60 fullerene is more preferable.

Examples of the rubrene compound include unsubstituted rubrene and rubrene substituted with an alkyl group or a halogen group.

Examples of the thiophene compound include unsubstituted oligothiophenes (terthiophene, quarterthiophene, sexithiophene, octithiophene, etc.), oligothiophenes substituted with an alkyl group or a halogen group, oligothiophenes substituted with a dicyanovinylene group, and oligothiophenes substituted with an alkyl group, a halogen group, and a dicyanovinylene group. When substituted with a dicyanovinylene group, it is preferable that the dicyanovinylene group is substituted at both ends of the oligothiophene. Examples of such compounds include 3',4'-dibutyl-5,5"-bis(dicyanovinyl)-2,2'-5',2"-terthiophene (DCV3T).

The electron transport layer 5 is not an essential component of the light-emitting/receiving element of the present invention. However, by providing the electron transport layer 5, an interface state suitable for extracting or injecting carriers can be formed, and short-circuiting between electrodes can be prevented. Therefore, in the present invention, the light-emitting/receiving element is preferably provided with the electron transport layer 5. For example, the light-emitting/receiving element 10 shown in FIG. 3 includes the electron transport layer 5 between the cathode 6 and the light-emitting/receiving layer 4.

For example, as a material for forming the electron transport layer 5, an organic material exhibiting n-type semiconductor characteristics such as the above-mentioned electron accepting organic materials (NTCDA, PTCDA, PTCDI-CH, oxazole derivatives, triazole derivatives, phenanthroline derivatives, phosphine oxide derivatives, phosphine sulfide derivatives, quinoline derivatives, fullerene compounds, CNT, CN-PPV, etc.) is preferably used. In addition, ionic compounds such as ionic substituted fluorene-based polymers (Advanced Materials, 2011, vol. 23, pp. 4636-4643; Organic Electronics, 2009, vol. 10, pp. 496-500) and combinations of ionic substituted fluorene-based polymers and substituted thiophene-based polymers (Journal of American Chemical Society, 2011, vol. 133, pp. 8416-8419) and polyethylene oxide (Advanced Materials, 2011, vol. 133, pp. 8416-8419) have been reported. Materials), 2007, Vol. 19, pp. 1835-1838, etc. can also be used as the material for the electron transport layer 5.

In addition, as the material for the electron transport layer 5, a compound having an ionic group, such as an ammonium salt, an amine salt, a pyridinium salt, an imidazolium salt, a phosphonium salt, a carboxylate salt, a sulfonate salt, a phosphate salt, a sulfate ester salt, a phosphoric acid ester salt, a sulfate salt, a nitrate salt, an acetonate salt, an oxoacid salt, or a metal complex can be used.

Specifically, examples of the compound having an ionic group include ammonium chloride, ammonium acetate, ammonium phosphate, hexyltrimethylammonium bromide, tetrabutylammonium bromide, octadecyltrimethylammonium bromide, hexadecylpyridinium bromide, 1-butyl-3-methylimidazolium bromide, tributylhexadecylphosphonium bromide, zinc formate, zinc acetate, zinc propionate, zinc butyrate, zinc oxalate, sodium heptadecafluorononanoate, sodium myristate, and sodium benzoate. Examples of such an organic compound include lithium, sodium 1-hexadecanesulfonate, sodium dodecyl sulfate, sodium monododecyl phosphate, zinc acetylacetonate, ammonium chromate, ammonium metavanadate, ammonium molybdate, ammonium hexafluorozirconate, sodium tungstate, ammonium tetrachlorozincate, tetraisopropyl orthotitanate, lithium nickelate, potassium permanganate, silver-phenanthroline complex, AgTCNQ, and compounds used in the electron transport layer described in JP-A-2013-58714.

Examples of materials for the electron transport layer 5 include titanium oxide (TiO _x ) such as TiO ₂ , zinc oxide (ZnO _x ) such as ZnO, silicon oxide (SiO _x ) such as SiO ₂ , tin oxide (SnO _x ) such as SnO ₂ , tungsten oxide (WO x ) such as WO ₃ , tantalum oxide (TaO _x ) such as Ta _{2 O 3} , barium titanate (BaTi _x O _y ) such as BaTiO ₃ , barium zirconate (BaZr _x O _y ) such as BaZrO ₃ , zirconium oxide (ZrO _x ) such as ZrO ₂ , hafnium oxide (HfO _x ) such as HfO ₂ , and aluminum oxide (A) such as Al ₂ O _{3 .}
metal oxides such as zirconium silicate (ZrSiO _{4 ) (} ZrSixO _y ), nitrides such as silicon nitride (SiN _x ) (Si ₃ N _{4 )} , cadmium sulfide (CdS _x ) ₍ CdS), zinc selenide ( _ZnSe ), etc.
Also preferably used are inorganic materials such as semiconductors including zinc sulfides (ZnS _x ) such as _ZnS , and cadmium tellurides (CdTe _x ) such as CdTe.

Examples of methods for forming the electron transport layer 5 using the inorganic material include a method of applying a precursor solution of a metal salt or metal alkoxide of the inorganic material to a substrate and then heating to form a layer, and a method of applying a nanoparticle dispersion to a substrate to form a layer. At this time, depending on the heating temperature, heating time, and nanoparticle synthesis conditions, the reaction may not proceed completely, and may be partially hydrolyzed or partially condensed to form an intermediate product, a mixture of the precursor and the intermediate product, or a mixture of the precursor and the final product.

When a configuration in which the cathode 6 adjacent to the electron transport layer 5 has optical transparency is applied to the light receiving/emitting element 10, the electron transport layer 5 preferably has high optical transparency to the emission wavelength when a voltage is applied to the light receiving/emitting element 10 (specifically, the light receiving/emitting layer 4). That is, in this case, it is more preferable that the material of the electron transport layer 5 is a material that does not have optical absorption ability for the above-mentioned emission wavelength.

(Manufacturing method of light emitting/receiving device)
Next, a method for manufacturing the light emitting/receiving element according to the embodiment of the present invention will be described with reference to the light emitting/receiving element 10 shown in FIG. 3 as an example.

When manufacturing the light emitting/receiving element 10, first, a transparent electrode such as ITO is formed by a sputtering method or the like on the substrate 1. In this embodiment, this transparent electrode corresponds to the anode 2 shown in FIG.

Next, a mixture of PEDOT and PSS is applied onto the transparent electrode and dried, thereby forming a PEDOT:PSS layer on the transparent electrode. This PEDOT:PSS layer corresponds to the hole transport layer 3 shown in FIG. 3. Any method may be used to form the hole transport layer 3, such as spin coat application, blade coat application, slit die coat application, screen printing application, bar coater application, mold application, printing transfer method, immersion pull-up method, ink jet method, spray method, vacuum deposition method, etc. The method for forming the hole transport layer 3 may be selected according to the photoelectric conversion layer characteristics to be obtained, such as film thickness control and orientation control.

Next, for example, a diketopyrrolopyrrole boron complex compound is dissolved in a solvent to prepare a solution, and this solution is applied onto the hole transport layer 3 and dried. As a result, a layer of the light-emitting portion is formed on the hole transport layer 3. At this time, the diketopyrrolopyrrole boron complex compound functions as both an electron donor material and a light-emitting material. In addition, the solvent used at this time is preferably an organic solvent, and examples thereof include methanol, ethanol, butanol, toluene, xylene, o-chlorophenol, acetone, ethyl acetate, ethylene glycol, tetrahydrofuran, dichloromethane, chloroform, dichloroethane, chlorobenzene, dichlorobenzene, trichlorobenzene, chloronaphthalene, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, and γ-butyrolactone. The above-mentioned solvent may be a mixture of two or more of these organic solvents. The above-mentioned layer of the light-emitting portion can be formed by the same formation method as that of the hole transport layer 3.

Next, a layer of a fullerene compound (e.g., _C60 fullerene) serving as an electron-accepting material, i.e., a fullerene layer, is formed on the light-emitting layer by vacuum deposition. This fullerene layer corresponds to the light-receiving layer. The light-receiving and light-emitting layer 4 shown in FIG. 3 is formed by a mixed layer of the light-emitting layer (a layer made of a diketopyrrolopyrrole boron complex compound) and the light-receiving layer (fullerene layer), or a layer having a laminated structure in which these layers are laminated.

Next, an electron extraction layer is formed on the fullerene layer in the light-receiving and light-emitting layer 4 by vacuum deposition or sputtering. This electron extraction layer corresponds to the electron transport layer 5 shown in FIG. 3. Next, a metal electrode made of Al, Ag, or the like is formed on the electron extraction layer by vacuum deposition or sputtering. If the electron extraction layer is formed by vacuum deposition, it is preferable to continue forming the metal electrode while maintaining the vacuum. This metal electrode corresponds to the cathode 6 shown in FIG. 3.

(Application example of light emitting/receiving element)
The light-receiving and light-emitting element of the present invention (for example, the light-receiving and light-emitting element 10 shown in FIG. 3) can be applied to various electronic devices and light-sensing devices that utilize light-receiving and light-emitting functions. For example, it is useful for electronic devices that capture biometric information such as fingerprints and veins, biosensing devices that monitor pulse waves and blood oxygen levels, optical sensors that detect changes in the shape and movement of objects, and optical switches. Although not particularly shown, the electronic device has a plurality of the above-mentioned light-receiving and light-emitting elements on a substrate. Or, the electronic device has the above-mentioned light-receiving and light-emitting elements on a TFT array substrate. The biosensing device, the optical sensor, and the optical switch each have the above-mentioned light-receiving and light-emitting elements on a substrate, in the substrate, or in a housing. When these electronic devices, the biosensing devices, the optical sensors, and the optical switches each have a plurality of the above-mentioned light-receiving and light-emitting elements, these multiple light-receiving and light-emitting elements may be of the same configuration as each other, or may be of different configurations.

Furthermore, when the electronic device according to the present invention includes a plurality of the above-mentioned light-receiving and light-emitting elements on or within a substrate or a housing, it is preferable that the plurality of light-receiving and light-emitting elements are of the same configuration. In this case, at least one first light-receiving and light-emitting element among the plurality of light-receiving and light-emitting elements can emit light to irradiate an object, and a second light-receiving and light-emitting element other than the first light-receiving and light-emitting element can receive light that has passed through or been reflected by the object. In this way, an electronic device including a plurality of light-receiving and light-emitting elements of the same configuration can perform optical sensing in which "light emitted from at least one of the first light-receiving and light-emitting elements is irradiated onto an object, and the light that has passed through or been reflected by the object is received by the second light-receiving and light-emitting element (i.e., another light-receiving and light-emitting element that is not emitting light)."

The present invention will be described in more detail below based on examples. Note that the present invention is not limited to the following examples. In addition, among the compounds used in the examples, those using abbreviations are defined as shown below.
ITO: indium tin oxide LiF: lithium fluoride Eg: band gap DPPcy: A compound DPPcy, which is an example of a diketopyrrolopyrrole boron complex compound, is a compound represented by the following chemical formula.
TDCV-TPA: Tris[4-(5-dicyanomethylidenemethyl-2-thienyl)phenyl]amine TDCV-TPA is a compound represented by the following chemical formula.
Alq3: Tris(8-quinolinolato)aluminum 60PCBM: Phenyl _C61butyric acid methyl ester DCV3T: 3',4'-dibutyl-5,5"-bis(dicyanovinyl)-2,2'-5',2"-terthiophene

DPPcy was synthesized by the method described in a non-patent document (Scientific Reports, 2016, Vol. 6, p. 34096) and a patent document (International Publication No. WO 2019/151121).

Example 1
In Example 1, evaluation samples of the light emitting/receiving elements were produced by the method described below, and the produced light emitting/receiving elements were evaluated.

In the manufacturing method of the light-receiving element of Example 1, first, chloroform (0.2 mL) was added to a sample bottle containing DPPcy (0.2 mg), and then ultrasonically irradiated in an ultrasonic cleaner for 30 minutes to obtain solution A. In addition, a PEDOT:PSS solution (6.0 mL) and isopropyl alcohol (4.0 mL) were placed in a sample bottle and stirred to obtain solution B for forming a hole transport layer. As the PEDOT:PSS solution, "CLEVIOS P VP AI4083" manufactured by H.C. Starck was used.

Next, a 125 nm thick ITO transparent conductive layer (hereinafter abbreviated as ITO layer) was deposited on the glass substrate by sputtering, and the glass substrate was cut to a size of 38 mm x 46 mm, after which the ITO layer was patterned into a rectangular shape of 38 mm x 13 mm by photolithography. The glass substrate was then ultrasonically cleaned for 10 minutes with an alkaline cleaning solution (Furuuchi Chemical Co., Ltd., "Semicoclean" EL56), and then washed with ultrapure water.

Next, after the glass substrate was subjected to UV/ozone treatment for 30 minutes, the above-mentioned solution B was dropped onto the ITO layer of the glass substrate, applied by spin coating at 3000 rpm, and heat-treated on a hot plate for 30 minutes at 100° C. As a result, a PEDOT:PSS layer (hole transport layer) having a thickness of about 30 nm was formed on the ITO layer.

Next, the above solution A was dropped onto the PEDOT:PSS layer and applied by spin coating. As a result, a DPPcy layer with a thickness of 8 nm was formed on the hole transport layer. Thereafter, the glass substrate on which the DPPcy layer was formed and a deposition mask were placed in a vacuum deposition apparatus, and the apparatus was evacuated until the degree of vacuum within the apparatus was 1×10 ⁻³ Pa or less, and C ₆₀ fullerene with a thickness of 25 nm was deposited on the DPPcy layer by a resistance heating method. As a result, a light-receiving and light-emitting layer having a laminated structure of a DPPcy layer and a layer of C ₆₀ fullerene (hereinafter abbreviated as C60 layer) was formed.

Next, the glass substrate on which the C60 layer had been formed was taken out into the atmosphere, and the deposition mask was replaced with an electrode deposition mask, after which the glass substrate and the electrode deposition mask were placed in a vacuum deposition apparatus and evacuated again until the degree of vacuum in the apparatus reached 1×10 ⁻³ Pa or less. Next, a LiF layer having a thickness of 0.5 nm and an aluminum layer having a thickness of 100 nm to serve as an electrode (anode) were deposited on the C60 layer of the glass substrate by a resistance heating method.

In Example 1, a light-receiving/light-emitting device was produced by the above-mentioned manufacturing method, in which the area of the intersection between the striped ITO layer and the silver layer was 5 mm x 5 mm. The glass substrate of this light-receiving/light-emitting device was then transferred to a glove box under a nitrogen atmosphere, and a photocurable resin (XNR5570 manufactured by Nagase ChemteX Corporation) was applied to a glass (gas barrier layer substrate) measuring 20 mm x 20 mm, which was then attached to the center of the glass substrate. Next, the photocurable resin was cured by irradiating it with ultraviolet light (wavelength 365 nm, intensity 100 mWcm ^-2 ) for 1 minute.

In Example 1, the external quantum yield spectrum (light-receiving sensitivity spectrum) of the anode and cathode of the light-receiving/light-emitting element fabricated as described above was measured using a spectral sensitivity measurement device when the applied voltage was 0 V. Next, the emission spectrum was measured using a spectral irradiance measurement device when a current of 50 mA was applied to the light-receiving/light-emitting element. The obtained external quantum yield spectrum and emission spectrum were normalized by their respective maximum values, and the overlapping region (overlapping region) of these normalized spectra was estimated, and the ratio of the overlapping region to the entire region of the normalized emission spectrum was estimated. The overlapping region between the obtained external quantum yield spectrum (light-receiving sensitivity spectrum before normalization) and the normalized emission spectrum was also estimated in the same manner.

Next, a current of 50 mA was applied to the light emitting/receiving element of Example 1, and the light emitted was irradiated onto a silicon photodiode. The current value of this silicon photodiode was measured, thereby measuring the amount of light emitted by this light emitting/receiving element.

Next, a spectrophotometer was used to measure the reflection/absorption spectrum of the light receiving/emitting element of Example 1 when the element received light that was specularly reflected at an angle of 5°. The absorbance of the light receiving/emitting element was estimated by correcting the baseline by taking the difference between the reflection/absorption spectrum obtained and the minimum value in the wavelength range of 300 nm to 1200 nm.

Next, a chloroform solution of DPPcy prepared to a concentration of 5 g/L was applied to a glass substrate by spin coating to form a DPPcy layer with a thickness of 50 nm. In addition, a _C60 layer was formed on another glass substrate by depositing C60 fullerene to a thickness of 50 nm. A transmission absorption spectrum was obtained for each of these single material films using a spectrophotometer. The absorption coefficient was estimated from the obtained transmission absorption spectrum using the following formula.
Absorption coefficient (cm ⁻¹ )=absorbance/0.434/film thickness (cm ⁻¹ )

Further, the band gap (Eg) of each of the single material films was estimated from the absorption edge wavelength of the transmission absorption spectrum by the following formula.
Eg (eV) = 1240/absorption edge wavelength (nm)

Furthermore, for each of the single material films, the HOMO was measured using atmospheric photoelectron spectroscopy (RIKEN AC-2), and the LUMO was estimated using the following formula.
LUMO (eV) = HOMO (eV) - Eg (eV)

Next, in Example 1, the two light-receiving and light-emitting elements prepared as described above were placed in a dark room at a distance of 5 mm apart, and the glass substrate surfaces on the ITO layer side of these light-receiving and light-emitting elements were placed opposite each other. Then, a current of 50 mA was passed through one of the light-receiving and light-emitting elements to cause it to emit light, and a Keithley 2400 series source meter was connected to the other light-receiving and light-emitting element to measure the current value when the applied voltage was changed from -1 V to +1 V. In addition, the current value was measured when the applied voltage was changed from -1 V to +1 V in the dark without causing it to emit light. The light-receiving sensitivity to the light emitted from the light-receiving and light-emitting element of the same configuration was measured by subtracting the current value in the dark from the current value when the light was emitted at 0 V, and this was used as an index of the light-receiving sensitivity to the light emitted from the light-receiving and light-emitting element itself. In addition, the open circuit voltage (the voltage at which the current becomes 0) for the light emitted from the light-receiving and light-emitting element of the same configuration was read from the current-voltage characteristics measured during light emission.

Example 2
In Example 2, chloroform (0.2 mL) was added to a sample bottle containing DPPcy (0.4 mg), and the sample was subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner to obtain solution C. In Example 2, a light-receiving and light-emitting element was produced and measured in the same manner as in Example 1, except that solution A in Example 1 was replaced with solution C and the film thickness of the DPPcy layer was set to 15 nm.

Example 3
In Example 3, chloroform (0.2 mL) was added to a sample bottle containing DPPcy (1.0 mg), and the sample was subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner to obtain solution D. In Example 3, a light-receiving and light-emitting element was produced and measured in the same manner as in Example 1, except that solution A in Example 1 was replaced with solution D and the film thickness of the DPPcy layer was set to 40 nm.

Example 4
In Example 4, chloroform (0.2 mL) was added to a sample bottle containing DPPcy (2.0 mg), and the sample was subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner to obtain solution E. In Example 4, a light-receiving and light-emitting element was produced and measured in exactly the same manner as in Example 1, except that solution A in Example 1 was replaced with solution E and the film thickness of the DPPcy layer was set to 70 nm.

Example 5
In Example 5, a light emitting/receiving device was fabricated and measured in exactly the same manner as in Example 1, except that the thickness of the C60 layer was set to 40 nm.

(Example 6)
In Example 6, a light emitting/receiving device was fabricated and measured in exactly the same manner as in Example 2, except that the thickness of the C60 layer was 40 nm.

(Example 7)
In Example 7, a light emitting/receiving device was fabricated and measured in exactly the same manner as in Example 3, except that the thickness of the C60 layer was 40 nm.

(Example 8)
In Example 8, a light emitting/receiving device was fabricated and measured in exactly the same manner as in Example 4, except that the thickness of the C60 layer was 40 nm.

Example 9
In Example 9, a light emitting/receiving device was fabricated and measured in exactly the same manner as in Example 2, except that the thickness of the C60 layer was 75 nm.

Example 10
In Example 10, a light emitting/receiving device was fabricated and measured in exactly the same manner as in Example 3, except that the thickness of the C60 layer was 75 nm.

(Example 11)
In Example 11, a light emitting/receiving device was fabricated and measured in exactly the same manner as in Example 4, except that the thickness of the C60 layer was 75 nm.

Example 12
In Example 12, chloroform (0.2 mL) was added to a sample bottle containing 1.0 mg of rubrene, and the solution was then subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner to obtain solution I. In Example 12, a light-receiving and light-emitting element was produced and measured in exactly the same manner as in Example 1, except that solution A in the above-mentioned Example 1 was replaced with solution I, the DPPcy layer was a rubrene layer having a film thickness of 40 nm, and a DCV3T layer was formed by vacuum deposition to a film thickness of 25 nm instead of the C60 layer.

(Comparative Example 1)
In Comparative Example 1, chloroform (0.2 mL) was added to a sample bottle containing 1.0 mg of rubrene (manufactured by Tokyo Chemical Industry Co., Ltd.), and the solution was subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner to obtain solution F. In Comparative Example 1, a light-receiving and light-emitting element was produced and measured in exactly the same manner as in Example 1, except that solution A in the above-mentioned Example 1 was replaced with solution F and a rubrene layer with a film thickness of 40 nm was formed.

(Comparative Example 2)
In Comparative Example 2, chloroform (0.2 mL) was added to a sample bottle containing 1.0 mg of TDCV-TPA (manufactured by Aldrich), and the sample was subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner to obtain a solution G. In Comparative Example 2, a light-receiving and light-emitting element was produced and measured in exactly the same manner as in Example 1, except that solution A in the above-mentioned Example 1 was replaced with solution G and a TDCV-TPA layer with a thickness of 40 nm was formed.

(Comparative Example 3)
In Comparative Example 3, an Alq3 layer having a thickness of 40 nm was deposited on an ITO substrate, a quinacridone layer having a thickness of 40 nm was then deposited on the Alq3 layer, and an aluminum layer serving as an electrode was then deposited on the quinacridone layer to a thickness of 100 nm. In this manner, the light-receiving/emitting device of Comparative Example 3 was produced. In Comparative Example 3, the light-receiving/emitting device was measured in the same manner as in Example 1, except that the current condition for causing the light-receiving/emitting device to emit light was changed from 50 mA to 3 mA. The light-emitting condition of Comparative Example 3 was changed because the light-receiving/emitting device deteriorates and no longer emits light when a current larger than 3 mA is applied.

(Comparative Example 4)
In Comparative Example 4, chloroform (0.2 mL) was added to a sample bottle containing 1.0 mg of DPPcy and 1.0 mg of 60PCBM, and the solution was subjected to ultrasonic irradiation for 30 minutes in an ultrasonic cleaner to obtain Solution H. In Comparative Example 4, Solution A in the above-mentioned Example 1 was replaced with Solution H, a uniform mixed layer (film thickness 100 nm) of DPPcy and 60PCBM was formed, and _C60 fullerene was not vapor-deposited, but otherwise, a light-receiving and light-emitting element was produced and measured in exactly the same manner as in Example 1.

(Comparative Example 5)
In Comparative Example 5, ethyl acetate (0.2 mL) was added to a sample bottle containing 1.0 mg of DPPcy, and the solution was ultrasonically irradiated for 30 minutes in an ultrasonic cleaner to obtain a solution J. In Comparative Example 5, instead of the DPPcy layer in Example 1, a C60 layer having a thickness of 40 nm was formed by vacuum deposition, and instead of the C60 layer in Example 1, a DPPcy layer having a thickness of 40 nm was formed by applying solution J by spin coating. In Comparative Example 5, the light receiving and emitting device was produced and measured in the same manner as in Example 1, except for the formation of the C60 layer and the DPPcy layer. In Comparative Example 5, the light emission measurement showed no light emission, and the maximum light emission wavelength and the light emission spectrum could not be specified, so that the light absorption characteristics and light receiving and emitting characteristics could not be evaluated.

The materials and the measurement results of the above-mentioned Examples 1 to 12 and Comparative Examples 1 to 5 are summarized in the following Tables 1-1 to 1-3. In Tables 1-1 and 1-2, "C60" in the "receiving and emitting layer material" and "light absorption characteristics" columns means _C60 fullerene. In Table 1-2, "Em" in the "light emission characteristics" column means the maximum emission wavelength energy, and "current value" means the current value of the silicon photodiode. "Absorbance" in the "light absorption characteristics" column means the absorbance of the receiving and emitting element at the maximum emission wavelength. "Specific material" means a receiving and emitting layer material with Eg smaller than the maximum emission wavelength energy. "Absorption coefficient" means the single film absorption coefficient at the maximum emission wavelength of the receiving and emitting layer material with Eg smaller than the maximum emission wavelength energy. In Table 1-3, "light receiving sensitivity" in the "light receiving characteristics" column means the light receiving sensitivity (external quantum yield) of the receiving and emitting element at the maximum emission wavelength. "Percentage of overlapping area (1)" in the "Light receiving/emitting characteristics" column means the percentage of the overlapping area between the normalized light receiving sensitivity spectrum and the normalized emission spectrum to the entire area of the normalized emission spectrum. "Percentage of overlapping area (2)" means the percentage of the overlapping area between the light receiving sensitivity spectrum before normalization and the normalized emission spectrum to the entire area of the normalized emission spectrum. "Light receiving sensitivity" in the "Light receiving/emitting characteristics" column means the light receiving sensitivity to light emitted from a light receiving/emitting element of the same configuration. "Open circuit voltage" means the open circuit voltage to light emitted from a light receiving/emitting element of the same configuration.

Example 13
In Example 13, two independent light-receiving and light-emitting elements, each having a size of 5 mm×5 mm, were formed on the same glass substrate by the same method as in Example 7, with the distance between them being 3 mm, and a biosensing device was fabricated that had these two light-receiving and light-emitting elements on the glass substrate. In Example 13, the pulse wave of a human body was measured using the fabricated biosensing device. In detail, first, the subject's middle finger was brought into contact with the glass substrate surface of the biosensing device. Next, of these two independent light-receiving and light-emitting elements, a current of 50 mA was passed through one light-receiving and light-emitting element to cause it to emit light, and a Keithley 2400 series source meter was connected to the other light-receiving and light-emitting element to measure the current value (light-receiving current) at an applied voltage of 0 V every 0.1 seconds, thereby performing pulse wave measurement. In Example 13, for example, as shown in FIG. 4, a measurement result of a pulse wave represented by a light-receiving current for each measurement time was obtained.

(Example 14)
In Example 14, two independent light-receiving and light-emitting elements, each having a size of 5 mm×5 mm, were formed on the same glass substrate by the same method as in Example 12, with the distance between them being 3 mm, and a biosensing device was fabricated having these two light-receiving and light-emitting elements on the glass substrate. In Example 14, the pulse wave of a human body was measured using the fabricated biosensing device. In detail, first, the subject's middle finger was brought into contact with the glass substrate surface of the biosensing device. Next, of these two independent light-receiving and light-emitting elements, a current of 50 mA was passed through one light-receiving and light-emitting element to cause it to emit light, and a Keithley 2400 series source meter was connected to the other light-receiving and light-emitting element, and the current value (light-receiving current) when the applied voltage was set to 0 V was measured every 0.1 seconds to perform pulse wave measurement. In Example 14, for example, as shown in FIG. 5, a measurement result of a pulse wave represented by a light-receiving current for each measurement time was obtained.

(Comparative Example 6)
In Comparative Example 6, two independent light-receiving and light-emitting elements, each having a size of 5 mm×5 mm, were formed on the same glass substrate by the same method as in Comparative Example 1, with a distance of 3 mm between them, and a biosensing device was fabricated having these two light-receiving and light-emitting elements on the glass substrate. In Comparative Example 6, the pulse wave of the human body was measured using the fabricated biosensing device. In detail, first, the subject's middle finger was brought into contact with the glass substrate surface of the fabricated biosensing device. Next, of these two independent light-receiving and light-emitting elements, a current of 50 mA was passed through one light-receiving and light-emitting element to cause it to emit light, and a Keithley 2400 series source meter was connected to the other light-receiving and light-receiving element, and the current value (light-receiving current) when the applied voltage was set to 0 V was measured every 0.1 seconds to perform pulse wave measurement. In Comparative Example 6, as shown in FIG. 6, for example, a clear measurement result of the pulse wave could not be obtained.

As described above, the light-receiving element and the electronic device and biosensing device using the same according to the present invention are suitable for light-receiving elements having good light-receiving sensitivity to light emitted from light-receiving elements of the same configuration, and for electronic devices and biosensing devices using the same.

REFERENCE SIGNS LIST 1 Substrate 2 Anode 3 Hole transport layer 4 Light receiving/emitting layer 5 Electron transport layer 6 Cathode 10 Light receiving/emitting element 101 Normalized light receiving sensitivity spectrum 101A Light receiving sensitivity spectrum 102 Normalized light emission spectrum 103, 103A Overlap region

Claims (14)

An anode;
A cathode;
a light-receiving and light-emitting layer located between the anode and the cathode and made of two or more organic materials;
Equipped with
The light-receiving and light-emitting layer contains an electron-donating material and an electron-accepting material that satisfy the energy level relationship represented by the following formulas (1) and (2):
at least one of the electron donor material and the electron acceptor material is a light emitting/receiving layer material having a band gap smaller than a maximum light emission wavelength energy when a voltage is applied to the light emitting/receiving layer,
the electron donating material is unevenly distributed on the anode side in the light emitting and receiving layer,
an overlapping area between the normalized light receiving sensitivity spectrum and the normalized emission spectrum occupies 50% or more of the area of the normalized emission spectrum;
A light emitting/receiving element.
HOMO of electron donor material>HOMO of electron acceptor material (1)
LUMO of electron donor material>LUMO of electron acceptor material (2) an overlapping area between the light receiving sensitivity spectrum before normalization and the normalized emission spectrum occupies 5% or more of an area of the normalized emission spectrum;
The light emitting/receiving device according to claim 1 . the electron donating material is a material of the light emitting and receiving layer having a band gap smaller than the maximum light emission wavelength energy when a voltage is applied to the light emitting and receiving layer;
The light emitting/receiving device according to claim 1 . The absorbance at the maximum emission wavelength when a voltage is applied to the light emitting and receiving layer is 0.1 or more.
4. The light emitting/receiving device according to claim 1, wherein the light emitting/receiving device is a light emitting device. the absorption coefficient of a single film of the material of the light emitting and receiving layer at the maximum emission wavelength when a voltage is applied to the light emitting and receiving layer is 30,000 cm ⁻¹ or more;
5. The light emitting/receiving device according to claim 1, the light-receiving and light-emitting layer has at least one of a light-receiving portion and a light-emitting portion having a domain size of 40 nm or more;
6. The light emitting/receiving device according to claim 1, The maximum emission wavelength when a voltage is applied to the light emitting and receiving layer is 700 nm or more.
7. The light emitting/receiving device according to claim 1, the light emitting and receiving layer contains a diketopyrrolopyrrole boron complex compound and a fullerene compound,
The light emitting/receiving device according to any one of claims 1 to 7. the light emitting and receiving layer contains a rubrene compound and a thiophene compound,
The light emitting/receiving device according to any one of claims 1 to 7. A light emitting element according to any one of claims 1 to 9, comprising a plurality of light emitting/receiving elements on a substrate.
1. An electronic device comprising: The plurality of light emitting/receiving elements are light emitting/receiving elements having the same configuration.
11. The electronic device of claim 10. A light emitting/receiving element according to any one of claims 1 to 9 is provided,
The plurality of light emitting/receiving elements are light emitting/receiving elements having the same configuration,
Among the plurality of light receiving and emitting elements, at least one first light receiving and emitting element emits light to irradiate an object, and a second light receiving and emitting element other than the first light receiving and emitting element receives light transmitted through or reflected by the object.
1. An electronic device comprising: A light emitting element according to any one of claims 1 to 9 is provided on a TFT array substrate.
1. An electronic device comprising: A light emitting/receiving element according to any one of claims 1 to 9,
A biological sensing device comprising:

Images