WO2011004807A1

WO2011004807A1 - Organic photoelectric conversion element, solar cell using same, and optical sensor array

Info

Publication number: WO2011004807A1
Application number: PCT/JP2010/061445
Authority: WO
Inventors: 晃矢子和地; 野島　隆彦; 大久保　康; 伊東　宏明
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2009-07-10
Filing date: 2010-07-06
Publication date: 2011-01-13
Also published as: JPWO2011004807A1; JP5447521B2

Abstract

Disclosed are: an organic photoelectric conversion element or solar cell, which has high fill factor, high open circuit voltage, high photoelectric conversion efficiency and durability; and an organic semiconductor material which constitutes the organic photoelectric conversion element. Specifically disclosed is an organic photoelectric conversion element which comprises a negative electrode, a positive electrode, and a bulk heterojunction layer wherein a p-type semiconductor material and an n-type semiconductor material are mixed together. The organic photoelectric conversion element is characterized by having a layer, which is formed from a material that has a LUMO level lower than -1.4 eV and a glass transition temperature (Tg) of 50-280°C (inclusive), between the negative electrode and the bulk heterojunction layer.

Description

Organic photoelectric conversion element, solar cell using the same, and optical sensor array

The present invention relates to an organic photoelectric conversion element, a solar cell, and an optical sensor array, and more particularly to a bulk heterojunction type organic photoelectric conversion element, a solar cell using the organic photoelectric conversion element, and an optical array sensor.

Due to the recent rise in fossil energy, a system that can generate electric power directly from natural energy has been demanded. Solar cells using monocrystalline, polycrystalline, or amorphous Si, compound-based solar cells such as GaAs and CIGS, or Dye-sensitized photoelectric conversion elements (Gretzel cells) have been proposed and put into practical use.

However, the cost of generating electricity with these solar cells is still higher than the price of electricity generated and transmitted using fossil fuels, which has hindered widespread use. In addition, since heavy glass must be used for the substrate, reinforcement work is required at the time of installation, which is one of the causes that increase the power generation cost.

In this situation, as a solar cell that can achieve a power generation cost lower than that of fossil fuel, an electron donor layer (p-type semiconductor layer) and an electron acceptor layer ( A bulk heterojunction photoelectric conversion element having a bulk heterojunction layer mixed with an n-type semiconductor layer is proposed (see, for example, Patent Document 1 and Non-Patent Document 1).

Since these bulk heterojunction solar cells are formed by a coating process except for the anode and cathode, it is expected that they can be manufactured at high speed and at low cost, and may solve the above-mentioned problem of power generation cost. . Furthermore, unlike the Si solar cells, compound semiconductor solar cells, and dye-sensitized solar cells described above, there is no process at a temperature higher than 160 ° C., so it can be formed on a cheap and lightweight plastic substrate. Is done.

In addition to the initial manufacturing cost, the power generation cost must be calculated including the power generation efficiency and the durability of the element. In Non-Patent Document 1, in order to efficiently absorb the solar spectrum, a long wavelength is used. By using an organic polymer capable of absorbing up to 5%, conversion efficiency exceeding 5% has been achieved.

The photoelectric conversion efficiency is calculated by the product of short-circuit current (Jsc) × open-circuit voltage (Voc) × fill factor (FF), but generally includes organic photoelectric conversion elements including the above-described high-efficiency organic thin-film solar cells. Voc remains as low as about 0.55, and if these can be further improved, it is expected that further photoelectric conversion efficiency can be obtained.

Voc is generally said to be determined by the difference between the donor's HOMO level and the acceptor's LUMO level, but it is closely related to the built-in potential of the photoelectric conversion element and the selectivity of the charge. It is known that it is effective to optimize the charge transport layer.

There is a disclosure that by inserting a hole blocking layer made of bathocuproine (BCP) as in the organic EL element, the charge separation efficiency can be improved and the photoelectric conversion efficiency can be improved (for example, see Patent Document 2). Since these materials have high crystallinity and low solubility, there is a problem that it is difficult to apply them to a coating method with high productivity.

Moreover, although a TiOx layer is disclosed as a hole blocking layer that can be produced by a coating process (see, for example, Patent Document 3 and Non-Patent Document 1), moisture and titanium alkoxide are reacted to form a TiOx layer. In an organic photoelectric conversion element that needs to be deteriorated by moisture, it cannot be said to be a preferable production method, and has a problem in durability.

In addition, in an organic electroluminescence device (OLED) having a similar structure but having the opposite function, a carboline derivative or a diazacarbazole derivative is used for the hole blocking layer in order to improve the light emission efficiency. Although there is a disclosure (see, for example, Patent Documents 4 and 5), generally, whether a hole blocking layer functions as a hole blocking layer is determined by the relationship with the HOMO level of an adjacent layer. Any block layer is not necessarily applicable to an organic photoelectric conversion element. In particular, HOMO and LUMO of fullerene derivatives which are n-type semiconductors included in a bulk heterojunction photoelectric conversion layer (also referred to as a bulk heterojunction layer) Since it is relatively deep, it can be effectively applied to organic photoelectric conversion elements with a non-aqueous coating method. Development of the hole blocking layer which can be formed has been awaited.

JP-T 8-500701 Special table 2003-515933 gazette Special table 2008-533745 WO2004-053019 pamphlet WO2004-095889 pamphlet

An object of the present invention is to provide an organic photoelectric conversion element or solar cell having high fill factor, open circuit voltage, photoelectric conversion efficiency and durability, and an organic semiconductor material constituting the organic photoelectric conversion element.

The above object of the present invention is achieved by the following means.

1. In an organic photoelectric conversion device having a cathode, an anode, and a bulk heterojunction photoelectric conversion layer in which a p-type semiconductor material and an n-type semiconductor material are mixed, an LUMO level is present between the cathode and the bulk heterojunction photoelectric conversion layer. An organic photoelectric conversion element comprising a layer containing a material shallower than −1.4 eV and having a Tg (glass transition temperature) of 50 ° C. or higher and 280 ° C. or lower.

2. 2. The organic photoelectric device according to 1 above, wherein the material constituting the layer between the cathode and the bulk heterojunction photoelectric conversion layer is a compound having at least a partial structure represented by the following general formula (1): Conversion element.

(In the formula, each of Z ₁ and Z ₂ represents an atomic group that forms a substituted or unsubstituted aromatic heterocycle with a nitrogen atom.)
3. 3. The organic photoelectric conversion device as described in 1 or 2 above, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (2) .

(Wherein Z ₁ and Z ₃ each represent a group of atoms forming a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring together with —C═C—, and Z ₂ and Z ₄ each represent —C═C— (Represents a group of atoms forming a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring.)
4). 4. The compound according to any one of items 1 to 3, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (3): Organic photoelectric conversion element.

(Wherein X ₁ to X ₇ represent a substituted or unsubstituted carbon atom or a nitrogen atom.)
5. 5. The organic photoelectric conversion element as described in any one of 1 to 4 above, wherein the compound having a partial structure represented by the general formulas (1) to (3) is a low molecular compound.

6. 6. The organic material according to any one of 1 to 5, wherein the layer containing the compound having a partial structure represented by the general formulas (1) to (3) is produced by a solution coating method. Photoelectric conversion element.

7. 7. A solar cell comprising the organic photoelectric conversion element as described in any one of 1 to 6 above.

8. 7. An optical sensor array comprising the organic photoelectric conversion elements according to any one of 1 to 6 arranged in an array.

By implementing the present invention, it is possible to provide an organic thin film solar cell having high fill factor, open circuit voltage, photoelectric conversion efficiency, and durability.

It is sectional drawing which shows the solar cell which consists of a bulk hetero junction type organic photoelectric conversion element. It is sectional drawing which shows the solar cell which consists of an organic photoelectric conversion element provided with a tandem-type bulk heterojunction layer. It is a figure which shows the structure of an optical sensor array.

The inventors of the present invention have made extensive studies on the above problems and have a cathode, an anode, and a bulk heterojunction photoelectric conversion layer (also referred to as a bulk heterojunction layer) in which a p-type semiconductor material and an n-type semiconductor material are mixed. In an organic photoelectric conversion element, a layer made of a material having a LUMO level shallower than −1.4 eV and a Tg (glass transition temperature) of 50 ° C. or higher and 280 ° C. or lower exists between the bulk heterojunction layer and the cathode. It has been found that the above problems can be achieved. Further, as a material having a LUMO level between −1.4 eV and a Tg (glass transition temperature) of 50 ° C. or higher and 280 ° C. or lower between the bulk heterojunction layer and the cathode, the general formula (1), preferably It has been found that the effect appears more remarkably by using a compound having a partial structure represented by the general formula (2), more preferably the general formula (3).

Hereinafter, the present invention will be described in more detail.

(Configuration of organic photoelectric conversion element and solar cell)
FIG. 1 is a cross-sectional view showing an example of a solar cell composed of a bulk heterojunction organic photoelectric conversion element. In FIG. 1, a bulk heterojunction type organic photoelectric conversion element 10 includes a transparent electrode (generally an anode) 12, a hole transport layer 17, a bulk heterojunction type photoelectric conversion layer 14, and an electron transport layer 18 on one surface of a substrate 11. And a counter electrode (generally a cathode) 13 are sequentially stacked.

The substrate 11 is a member that holds the transparent electrode 12, the photoelectric conversion layer 14, and the counter electrode 13 that are sequentially stacked. In the present embodiment, since light that is photoelectrically converted enters from the substrate 11 side, the substrate 11 can transmit the light that is photoelectrically converted, that is, with respect to the wavelength of the light to be photoelectrically converted. It is a transparent member. As the substrate 11, for example, a glass substrate or a resin substrate is used. The substrate 11 is not essential. For example, the bulk heterojunction type organic photoelectric conversion element 10 may be configured by forming the transparent electrode 12 and the counter electrode 13 on both surfaces of the photoelectric conversion layer 14.

The photoelectric conversion layer 14 is a layer that converts light energy into electric energy, and includes a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

In FIG. 1, light incident from the transparent electrode 12 through the substrate 11 is absorbed by the electron acceptor or electron donor in the bulk heterojunction layer of the photoelectric conversion layer 14, and electrons move from the electron donor to the electron acceptor. Thus, a hole-electron pair (charge separation state) is formed. The generated electric charge is caused by an internal electric field, for example, when the work functions of the transparent electrode 12 and the counter electrode 13 are different, the electrons pass between the electron acceptors due to the potential difference between the transparent electrode 12 and the counter electrode 13, and the holes are The photocurrent is detected as it passes between the donors and is carried to different electrodes. For example, when the work function of the transparent electrode 12 is larger than the work function of the counter electrode 13, electrons are transported to the transparent electrode 12 and holes are transported to the counter electrode 13. If the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction. In addition, by applying a potential between the transparent electrode 12 and the counter electrode 13, the transport direction of electrons and holes can be controlled.

Although not shown in FIG. 1, other layers such as a hole blocking layer, an electron blocking layer, an electron injection layer, a hole injection layer, or a smoothing layer may be further included.

Furthermore, for the purpose of improving the sunlight utilization rate (photoelectric conversion efficiency), a tandem configuration in which such photoelectric conversion elements are stacked may be employed. FIG. 2 is a cross-sectional view showing a solar cell composed of an organic photoelectric conversion element including a tandem type bulk heterojunction layer. In the case of the tandem configuration, the transparent electrode 12 and the first photoelectric conversion layer 14 'are sequentially stacked on the substrate 11, the charge recombination layer 15 is stacked, the second photoelectric conversion layer 16, and then the counter electrode. By stacking 13, a tandem configuration can be obtained. The second photoelectric conversion layer 16 may be a layer that absorbs the same spectrum as the absorption spectrum of the first photoelectric conversion layer 14 'or may be a layer that absorbs a different spectrum, but is preferably a layer that absorbs a different spectrum. is there.

[Electron transport layer (hole blocking layer)]
The inventors of the present invention have made extensive studies, and by using the organic compound material as described above for the electron transport layer (hole blocking layer), the open circuit voltage Voc (V) is large and the photoelectric conversion efficiency is excellent. It has been found that it becomes an organic photoelectric conversion element.

By forming the electron transport layer 18, it is possible to extract charges generated in the bulk heterojunction layer more efficiently.

In addition, the electron transport layer having a HOMO level deeper than the HOMO level of the p-type semiconductor material used for the bulk heterojunction layer has a rectifying effect so that holes generated in the bulk heterojunction layer do not flow to the cathode side. The hole blocking function is imparted. Such an electron transport layer is also called a hole blocking layer, and it is preferable to use an electron transport layer having such a function.

In the present invention, in addition to the material according to the present invention, a conventionally used material may be used in combination. Examples of such materials include phenanthrene compounds such as bathocuproine, n-type semiconductor materials such as naphthalenetetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide, and titanium oxide. Examples thereof include n-type inorganic oxides such as zinc oxide and gallium oxide, and alkali metal compounds such as lithium fluoride, sodium fluoride, and cesium fluoride. Alternatively, a single n-type semiconductor material used for the bulk heterojunction layer can be used.

The means for forming these layers may be either a vacuum vapor deposition method or a solution coating method, but is preferably a solution coating method.

The film thickness of the electron transport layer (hole blocking layer) is 5 nm to 5 μm, preferably 5 nm to 200 nm.

Voc is generally said to be determined by the difference between the donor's HOMO level and the acceptor's LUMO level, but it is closely related to the built-in potential of the photoelectric conversion element and the selectivity of the charge. It is known that it is effective to optimize the level of HOMO or LUMO of the charge transport layer.

Further, for example, it is disclosed that the charge separation efficiency can be improved and the photoelectric conversion efficiency can be improved by inserting an electron transport layer made of bathocuproine (BCP) between the bulk heterojunction layer and the cathode as in the organic EL element. However, since these materials have high crystallinity and low solubility, it is difficult to apply them to a coating method with high productivity. Therefore, the present inventors have conducted various studies on a material that has a lower glass transition point that can be expected to improve solubility and a weak crystallization tendency and that is optimized for the LUMO level. Excellent organic photoelectric conversion with a high photoelectric conversion efficiency by using a layer made of an organic material having a LUMO level shallower than −1.4 eV and a relatively low Tg (glass transition temperature) of 50 ° C. or higher and 280 ° C. or lower. It has been found that it becomes an element.

In the conventional technique, the LUMO level of the electron transport layer is close to the LUMO level of the fullerene derivative contained in the photoelectric conversion layer (the LUMO level in the molecular orbital calculation in the case of PCBM used in the example is −3.13 eV). Has been considered preferable because the interface barrier that hinders the transport of charges is reduced, but the electron transport layer containing an electron transport material having a shallow LUMO level as in the present invention is referred to as a photoelectric conversion layer. Even when it is provided between the electrodes, there is almost no decrease in the fill factor FF, which is expected to come from the barrier of the interface, and the open circuit voltage Voc is improved as described above. As a result, the overall efficiency is improved. I found out.

Some examples of organic materials with these characteristics are listed below.

As these materials, it is more preferable to use a compound having a partial structure represented by the general formulas (1), (2), and (3).

The organic photoelectric conversion element 10 of the present invention can extract charges generated in the bulk heterojunction layer more efficiently by forming the electron transport layer 18 according to the present invention between the bulk heterojunction layer and the cathode. Become.

In the present invention, a compound having a LUMO level shallower than −1.4 eV is used as the electron transport layer 18, and these compounds are simultaneously HOMO deeper than the HOMO level of the p-type semiconductor material used for the bulk heterojunction layer. It has a level and has a rectifying effect that prevents holes generated in the bulk heterojunction layer from flowing to the cathode side, that is, a hole blocking function is provided.

In the present invention, the compound having a partial structure represented by the general formulas (1) to (3) of the present invention having a shallow LUMO level and high electron mobility is used as an electron transporting layer (also serving as a hole blocking layer). Thus, effects such as improvement of the fill factor and photoelectric conversion efficiency can be obtained.

The HOMO and LUMO levels of a molecule can be determined from photoelectron emission measurement (UPS), UV-Vis spectrum measurement results, molecular orbital calculation (B3LYP / 6-31G ^* ), and the like. The LUMO level is a value obtained by molecular orbital calculation (B3LYP / 6-31G ^* ). Here, the LUMO level being shallow means that the LUMO level has a numerical value larger than −1.4 eV and a small absolute value.

In addition, the glass transition point (Tg) is measured using a differential scanning calorimeter.

The measurement conditions are 0-300 ° C, temperature increase rate 10 ° C / min, temperature decrease rate 10 ° C / min, with heat-cool-heat control, and analysis based on the 2nd heat data. went. The glass transition temperature is obtained by drawing an extension of the baseline before the rise of the first endothermic peak and a tangent line indicating the maximum slope between the rising portion of the first peak and the peak apex, and the intersection is defined as the glass transition point. did.

The material according to the present invention is a material having a LUMO level shallower than −1.4 eV and a Tg (glass transition temperature) of 50 ° C. or higher and 280 ° C. or lower, preferably 50 ° C. or higher and 150 ° C. or lower. It is.

In the present invention, the electron transport layer (hole block layer) material is preferably a low-molecular compound from the viewpoint that high-purity purification is possible and that a thin film with high mobility can be obtained. When defining by molecular weight for practical use, a compound having a molecular weight of 3000 or less is preferably classified as a low molecular compound. More preferably, it is 2500 or less, More preferably, it is 2000 or less. On the other hand, a compound having a molecular weight of 2000 or more, more preferably 3000 or more, and further preferably 5000 or more is classified as a polymer compound. The molecular weight can be measured by gel permeation chromatography (GPC).

The compound having a partial structure represented by the general formulas (1), (2), and (3) that are preferably used in the present invention will be described.

In the general formula (1), Z ₁ and Z ₂ each represent an atomic group that forms a substituted or unsubstituted aromatic heterocyclic ring together with a nitrogen atom, and the formed rings may be different from each other.

The aromatic heterocycle formed by Z ₁ and Z ₂ in the general formula (1) preferably has a nitrogen atom number in the range of 1 to 3, but from the stability of the compound, the nitrogen atom number is 1 to 2. Preferably one.

The general formula (1) is preferably represented by the general formula (2).

In the general formula (2), Z ₁ and Z ₃ each represent an atomic group forming a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring together with —C═C—, and Z ₂ and Z ₄ are each —C═ A group of atoms forming a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring together with C-.

The general formula (2) nitrogen-containing aromatic 6-membered ring formed respectively at Z1, Z ₃ in, the number of nitrogen atoms is preferably in the range of 1-3, nitrogen atoms from the viewpoint of stability of the compound is 1 - 2, more preferably one. The positions occupied by nitrogen atoms are the γ-position and δ-position from the viewpoint of stability of the compound when the α-position, β-position, γ-position, and δ-position from the side close to the nitrogen atom of the central nitrogen-containing 5-membered ring are used. It is preferable that More preferred is a structure in which a nitrogen atom is substituted at the δ position in the general formula (3).

Z ₂ and Z ₄ each represents an atomic group that forms a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring together with —C═C—, and examples of the aromatic heterocyclic ring include Z ₁ , Z ₃ is preferable, and examples of the aromatic hydrocarbon ring include a benzene ring and a naphthalene ring.

The general formula (1) is more preferably represented by the general formula (3).

In the general formula (3), X ₁ to X _{7 each} represent a substituted or unsubstituted carbon atom or nitrogen atom.

In order to obtain a high open-circuit voltage, a higher effect can be obtained by replacing carbon atoms of the carbazole-like ring in the general formula (3) with a large number of nitrogen atoms. On the other hand, since the stability of the compound is reduced, In order to achieve both high open-circuit voltage and stability of the compound, a ring formed by —C═C— and X ₁ to X ₄ and a ring formed by —C═C—N = and X ₅ to X ₇ It is preferable to use aromatic 6-membered rings each containing one nitrogen atom. In this case as well, the γ-position and the δ-position are preferred as the position where the nitrogen atom is substituted, and among them, a structure in which both the δ-position is substituted with the nitrogen atom is preferred.

The general formulas (1) to (3) are partial structures, and the general formulas (1) to (3) may be substituted with various substituents. Examples of these groups include halogen atoms. Represents a substituent selected from a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.

Hereinafter, specific examples of the compound having a partial structure represented by the general formulas (1) to (3) of the present invention will be given.

In addition to the compound examples 1 and 2, the following compounds may be mentioned, but the present invention is not limited thereto.

From the viewpoint of being able to purify with high purity and obtaining a thin film with high mobility, these are also preferably low molecular weight compounds. The low molecular weight compound is as defined above.

Compounds having such a structure are disclosed in WO 2004-95891, Tetrahedron vol. 51, no. 44 (1995), p12127 and the like can be synthesized.

[Photoelectric conversion layer]
In the practice of the present invention, the photoelectric conversion layer 14 described above is a layer that converts light energy into electrical energy, and has a so-called bulk heterojunction structure in which at least a p-type semiconductor material and an n-type semiconductor material are mixed.

The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). It is characterized by being formed by a coating method. In the case of forming by a coating method, in order to form a bulk heterojunction structure and improve photoelectric conversion efficiency, it is preferably annealed at a predetermined temperature in a step after coating and partially crystallized microscopically.

In FIG. 1, light incident from the anode 12 through the substrate 11 is absorbed by the electron acceptor or electron donor in the bulk heterojunction layer of the photoelectric conversion layer 14, and electrons move from the electron donor to the electron acceptor. A hole-electron pair (charge separation state) is formed. In the case where the generated electric charges have different internal electric fields, for example, when the work functions of the anode 12 and the cathode 13 are different, due to the potential difference between the anode 12 and the cathode 13, electrons pass between electron acceptors and holes are electron donors. The photocurrent is detected by being carried to different electrodes. For example, when the work function of the anode 12 is larger than that of the cathode 13, electrons are transported to the anode 12 and holes are transported to the cathode 13. If the magnitude of the work function is reversed, electrons and holes are easily transported in the opposite direction. In addition, the transport direction of electrons and holes can be controlled by applying a potential between the anode 12 and the cathode 13.

[N-type semiconductor materials]
Examples of n-type semiconductor materials include fullerene, octaazaporphyrin, p-type semiconductor perfluoro compounds (perfluoropentacene, perfluorophthalocyanine, etc.), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetracarboxylic acid Examples thereof include polymer compounds containing an anhydride, an aromatic carboxylic acid anhydride such as perylenetetracarboxylic acid diimide, or an imidized product thereof as a skeleton.

[P-type semiconductor materials]
Examples of the p-type semiconductor material used in the present invention include various condensed polycyclic aromatic compounds and conjugated compounds.

As the condensed polycyclic aromatic compound, for example, anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, sarkham anthracene, bisanthene, zestrene, heptazelene, Examples thereof include compounds such as pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, and derivatives and precursors thereof.

Examples of the conjugated compound include polythiophene and its oligomer, polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, tetrathiafulvalene compound, quinone Compounds, cyano compounds such as tetracyanoquinodimethane, fullerenes and derivatives or mixtures thereof.

In particular, among polythiophene and oligomers thereof, thiophene hexamer α-seccithiophene α, ω-dihexyl-α-sexualthiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3- An oligomer such as butoxypropyl) -α-sexithiophene can be preferably used.

Other examples of the polymer p-type semiconductor include polyacetylene, polyparaphenylene, polypyrrole, polyparaphenylene sulfide, polythiophene, polyphenylene vinylene, polycarbazole, polyisothianaphthene, polyheptadiyne, polyquinoline, polyaniline, and the like. Substituted-unsubstituted alternating copolymer polythiophenes such as JP-A-2006-36755, JP-A-2007-51289, JP-A-2005-76030, J. Pat. Amer. Chem. Soc. , 2007, p4112, J.A. Amer. Chem. Soc. , 2007, p7246, etc., polymers having a condensed ring thiophene structure, WO2008 / 000664, Adv. Mater. , 2007, p4160, Macromolecules, 2007, Vol. Examples thereof include thiophene copolymers such as 40 and p1981.

Further organic compounds such as porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF) -perchloric acid complex, BEDTTTTF-iodine complex, TCNQ-iodine complex, etc. Molecular complexes, fullerenes such as C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ and C ₈₄ , carbon nanotubes such as SWNT, dyes such as merocyanine dyes and hemicyanine dyes, and σ-conjugated systems such as polysilane and polygermane Polymers and organic / inorganic hybrid materials described in JP 2000-260999 A can also be used.

[Method of forming bulk heterojunction layer]
Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, the coating method is preferable in order to increase the area of the interface where charges and electrons are separated from each other as described above and to produce a device having high photoelectric conversion efficiency. The coating method is also excellent in production speed.

After application, it is preferable to perform heating in order to cause removal of residual solvent, moisture, and gas, and improvement of mobility and absorption of long wave by crystallization of the semiconductor material. When annealing is performed at a predetermined temperature during the manufacturing process, a part of the particles is microscopically aggregated or crystallized, and the bulk heterojunction layer can have an appropriate phase separation structure. As a result, the carrier mobility of the bulk heterojunction layer is improved and high efficiency can be obtained.

The photoelectric conversion layer (bulk heterojunction layer) 14 may be composed of a single layer in which the electron acceptor and the electron donor are uniformly mixed, but a plurality of the mixture ratios of the electron acceptor and the electron donor are changed. It may consist of layers. In this case, it can be formed by using a material that can be insolubilized after coating as described above.

[Hole Transport Layer / Electron Blocking Layer]
In the organic photoelectric conversion element 10 of the present invention, the hole transport layer 17 can be taken out between the bulk heterojunction layer and the anode, and charges generated in the bulk heterojunction layer can be taken out more efficiently. It is preferable to have.

As a material constituting these layers, for example, as the hole transport layer 17, PEDOT such as trade name BaytronP, polyaniline and its doped material, cyan compound described in WO2006019270, etc. Can be used. Note that the hole transport layer having a LUMO level shallower than the LUMO level of the n-type semiconductor material used for the bulk heterojunction layer has a rectifying effect that prevents electrons generated in the bulk heterojunction layer from flowing to the anode side. It has an electronic block function. Such a hole transport layer is also called an electron block layer, and it is preferable to use a hole transport layer having such a function. As such materials, triarylamine compounds described in JP-A-5-271166, metal oxides such as molybdenum oxide, nickel oxide, and tungsten oxide can be used. A layer made of a single p-type semiconductor material used for the bulk heterojunction layer can also be used. The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method. Forming the coating film in the lower layer before forming the bulk heterojunction layer is preferable because it has the effect of leveling the coating surface and reduces the influence of leakage and the like.

[Other layers]
For the purpose of improving energy conversion efficiency and improving the lifetime of the element, a structure having various intermediate layers in the element may be employed. Examples of the intermediate layer include a hole block layer, an electron block layer, a hole injection layer, an electron injection layer, an exciton block layer, a UV absorption layer, a light reflection layer, and a wavelength conversion layer.

<electrode>
The photoelectric conversion element according to the present invention has at least an anode and a cathode. Further, when a tandem configuration is adopted, the tandem configuration can be achieved by using an intermediate electrode. In the present invention, an electrode through which holes mainly flow is called an anode, and an electrode through which electrons mainly flow is called a cathode.

Also, because of the function of whether or not there is translucency, there is a case where the translucent electrode is called a transparent electrode and the non-translucent electrode is called a counter electrode. Usually, the anode is a translucent transparent electrode, and the cathode is a non-translucent counter electrode.

〔anode〕
The anode of the present invention is preferably an electrode that transmits light of 380 to 800 nm. As the material, for example, transparent conductive metal oxides such as indium tin oxide (ITO), SnO ₂ and ZnO, metal thin films such as gold, silver and platinum, metal nanowires and carbon nanotubes can be used.

Also, a conductive material selected from the group consisting of polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polyphenylacetylene, polydiacetylene and polynaphthalene. A functional polymer can also be used. Further, a plurality of these conductive compounds can be combined to form an anode.

〔cathode〕
The cathode may be a single layer of a conductive material, but in addition to a conductive material, a resin that holds these may be used in combination. As a conductive material for the cathode, a material having a work function (4 eV or less) metal, alloy, electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the viewpoint of electron extraction performance and durability against oxidation, etc., a mixture of these metals and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, magnesium / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

If a metal material is used as the conductive material of the cathode, the light coming to the cathode side is reflected and reflected to the first electrode side, and this light can be reused and absorbed again by the photoelectric conversion layer, further improving the photoelectric conversion efficiency. It is preferable.

Further, the cathode 13 may be a metal (for example, gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, indium, etc.), a nanoparticle made of carbon, a nanowire, or a nanostructure. A dispersion is preferable because a transparent and highly conductive cathode can be formed by a coating method.

Further, when the cathode side is made light transmissive, for example, a conductive material suitable for the cathode such as aluminum and aluminum alloy, silver and silver compound is made thin with a film thickness of about 1 to 20 nm, and then the anode By providing a film of the conductive light-transmitting material mentioned in the description, a light-transmitting cathode can be obtained.

[Intermediate electrode]
The intermediate electrode material required in the case of the tandem structure as shown in FIG. 2 is preferably a layer using a compound having both transparency and conductivity. Transparent metal oxides such as ITO, AZO, FTO and titanium oxide, very thin metal layers such as Ag, Al and Au, or layers containing nanoparticles / nanowires, conductive polymer materials such as PEDOT: PSS and polyaniline Etc.) can be used.

In addition, in the hole transport layer and the electron transport layer described above, there is also a combination that works as an intermediate electrode (charge recombination layer) by appropriately combining and laminating, and with such a configuration, the process of forming one layer This is preferable because it can be omitted.

〔substrate〕
When light that is photoelectrically converted enters from the substrate side, the substrate is preferably a member that can transmit the light that is photoelectrically converted, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted. As the substrate, for example, a glass substrate, a resin substrate and the like are preferably mentioned, but it is desirable to use a transparent resin film from the viewpoint of light weight and flexibility. There is no restriction | limiting in particular in the transparent resin film which can be preferably used as a transparent substrate by this invention, The material, a shape, a structure, thickness, etc. can be suitably selected from well-known things. For example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) modified polyester, polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, polyolefin resins such as cyclic olefin resin Film, vinyl resin film such as polyvinyl chloride, polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF) resin film, polyether sulfone (PES) resin film, polycarbonate (PC) resin film, A polyamide resin film, a polyimide resin film, an acrylic resin film, a triacetyl cellulose (TAC) resin film, and the like can be given. If the resin film transmittance of 80% or more in ~ 800 nm), can be preferably applied to a transparent resin film according to the present invention. Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. More preferred are polyethylene terephthalate films and biaxially stretched polyethylene naphthalate films.

The transparent substrate used in the present invention can be subjected to a surface treatment or an easy adhesion layer in order to ensure the wettability and adhesion of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment. Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

Further, for the purpose of suppressing the permeation of oxygen and water vapor, a barrier coat layer may be formed in advance on the transparent substrate, or a hard coat layer may be formed in advance on the opposite side to which the transparent conductive layer is transferred. Good.

(Optical function layer)
The organic photoelectric conversion element of the present invention may have various optical functional layers for the purpose of more efficient reception of sunlight. As the optical functional layer, for example, a light condensing layer such as an antireflection film or a microlens array, or a light diffusion layer that can scatter light reflected by the cathode and enter the power generation layer again may be provided. .

Various known antireflection layers can be provided as the antireflection layer. For example, when the transparent resin film is a biaxially stretched polyethylene terephthalate film, the refractive index of the easy adhesion layer adjacent to the film is 1.57. It is more preferable to set it to ˜1.63 because the transmittance can be improved by reducing the interface reflection between the film substrate and the easy adhesion layer. The method for adjusting the refractive index can be carried out by appropriately adjusting the ratio of the oxide sol having a relatively high refractive index such as tin oxide sol or cerium oxide sol and the binder resin. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion.

As the condensing layer, for example, it is processed so as to provide a structure on the microlens array on the sunlight receiving side of the support substrate, or the amount of light received from a specific direction is increased by combining with a so-called condensing sheet. Conversely, the incident angle dependency of sunlight can be reduced.

As an example of a microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

Also, examples of the light scattering layer include various antiglare layers, layers in which nanoparticles or nanowires such as metals or various inorganic oxides are dispersed in a colorless and transparent polymer, and the like.

[Patterning]
The method and process for patterning the electrode, the power generation layer, the hole transport layer, the electron transport layer, and the like according to the present invention are not particularly limited, and known methods can be appropriately applied.

If it is a soluble material such as a bulk heterojunction layer and a transport layer, only unnecessary portions may be wiped after the entire surface of die coating, dip coating, etc., or direct patterning at the time of coating using a method such as an ink jet method or screen printing. May be.

In the case of an insoluble material such as an electrode material, the electrode can be patterned by a known method such as mask vapor deposition during vacuum deposition or etching or lift-off. Alternatively, the pattern may be formed by transferring a pattern formed on another substrate.

(Sealing)
Moreover, since the produced organic photoelectric conversion element 10 does not deteriorate with oxygen, moisture, etc. in the environment, it is preferable to seal not only the organic photoelectric conversion element but also an organic electroluminescence element by a known method. For example, a method of sealing a cap made of aluminum or glass by bonding with an adhesive, a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed and the organic photoelectric conversion element top 10 with an adhesive Method of bonding, spin coating of organic polymer materials with high gas barrier properties (polyvinyl alcohol, etc.), inorganic thin films with high gas barrier properties (silicon oxide, aluminum oxide, etc.) or organic films (parylene, etc.) deposited under vacuum And a method of laminating these in a composite manner.

(Optical sensor array)
Next, an optical sensor array to which the bulk heterojunction type organic photoelectric conversion element 10 described above is applied will be described in detail. The optical sensor array is produced by arranging the photoelectric conversion elements in a fine pixel form by utilizing the fact that the bulk heterojunction type organic photoelectric conversion elements generate a current upon receiving light, and projected onto the optical sensor array. A sensor having an effect of converting an image into an electrical signal.

FIG. 4 is a diagram showing the configuration of the optical sensor array. 4A is a top view, and FIG. 4B is a cross-sectional view taken along line A-A ′ of FIG. 4A.

In FIG. 4, an optical sensor array 20 is paired with an anode 22 as a lower electrode, a photoelectric conversion layer 24 that converts light energy into electric energy, and an anode 22 on a substrate 21 as a holding member. The cathode 23 is sequentially laminated. The photoelectric conversion layer 24 includes two layers, a photoelectric conversion layer 24b having a bulk hetero junction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed, and a buffer layer 24a. In the example shown in FIG. 4, six bulk heterojunction type organic photoelectric conversion elements are formed.

The substrate 21, the anode 22, the photoelectric conversion layer 24b, and the cathode 23 have the same configuration and role as the anode 12, the photoelectric conversion layer 14, and the cathode 13 in the bulk heterojunction photoelectric conversion element 10 described above.

For example, glass is used for the substrate 21, ITO is used for the anode 22, and aluminum is used for the cathode 23, for example. For example, the BP-1 precursor is used for the p-type semiconductor material of the photoelectric conversion layer 24b, and for example, the exemplified compound 13 is used for the n-type semiconductor material. The buffer layer 24a is made of PEDOT (poly-3,4-ethylenedioxythiophene) -PSS (polystyrene sulfonic acid) conductive polymer (trade name BaytronP, manufactured by Stark Vitec). Such an optical sensor array 20 was manufactured as follows.

An ITO film was formed on the glass substrate by sputtering and processed into a predetermined pattern shape by photolithography. The thickness of the glass substrate was 0.7 mm, the thickness of the ITO film was 200 nm, and the measurement area (light receiving area) of the ITO film after photolithography was 0.5 mm × 0.5 mm. Next, a PEDOT-PSS film was formed on the glass substrate 21 by spin coating (conditions: rotational speed = 1000 rpm, filter diameter = 1.2 μm). Thereafter, the substrate was heated in an oven at 140 ° C. for 10 minutes and dried. The thickness of the PEDOT-PSS film after drying was 30 nm.

Next, a 1: 1 mixed film of P3HT (poly-3hexylthiophene) and PCBM is formed on the PEDOT-PSS film by spin coating (conditions: rotational speed = 3300 rpm, filter diameter = 0.8 μm). did. In this spin coating, P3HT and PCBM were mixed with a chlorobenzene solvent in a ratio of 1: 1, and a mixture obtained by stirring (5 minutes) was used. After forming the mixed film of P3HT and PCBM, annealing was performed by heating in an oven at 180 ° C. for 30 minutes in a nitrogen gas atmosphere. The thickness of the mixed film of P3HT and PCBM after the annealing treatment was 70 nm.

Then, using a metal mask having a predetermined pattern opening, 5 nm of the compound 16 of the present invention is deposited as an electron transport layer on a mixed film of P3HT and PCBM, and then an aluminum layer as a cathode is formed by a deposition method ( (Thickness = 10 nm). Thereafter, 1 μm of PVA (polyvinyl alcohol) was formed by spin coating and baked at 150 ° C. to prepare a passivation layer (not shown). The optical sensor array 20 was produced as described above.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<Preparation of organic photoelectric conversion element SC-101>
The transparent electrode patterned on the glass substrate is cleaned in the order of ultrasonic cleaning with surfactant and ultrapure water, then ultrasonic cleaning with ultrapure water, dried with nitrogen blow, and finally UV ozone cleaning. It was.

The glass substrate having this transparent electrode was spin-coated with a conductive polymer, Baytron P4083 (manufactured by Starck Vitec), with a film thickness of 30 nm, and then heat-dried at 140 ° C. for 10 minutes in the air.

After this, the substrate was brought into the glove box and worked in a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere. A solution was prepared by dissolving 1.5% by mass of Plexcore OS2100 manufactured by Plextronics as p-type semiconductor material and 1.5% by mass of E100 (PCBM) manufactured by Frontier Carbon as n-type semiconductor material in chlorobenzene. While being filtered through a 45 μm filter, spin coating was performed at 500 rpm for 60 seconds, then at 2200 rpm for 1 second, and left at room temperature for 30 minutes.

Next, a solution prepared by mixing Exemplified Compound 2 (described in Table 1 below) with 2,2,3,3-tetrafluoro-1-propanol at a ratio of 0.5 mass% was spin-coated at 1500 rpm, and an electron having a thickness of 10 nm A transport (hole blocking) layer was formed.

Next, the substrate on which the series of organic layers was formed was placed in a vacuum deposition apparatus without being exposed to the atmosphere. The element was set so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 10 −3 Pa or less, and then Al was deposited with a thickness of 100 nm. Finally, heating was performed at 120 ° C. for 30 minutes to obtain an organic photoelectric conversion element SC-101. The vapor deposition rate was 2 nm / second, and the size was 2 mm square.

The obtained organic photoelectric conversion element 1 was sealed using an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then taken out into the atmosphere.

<Production of organic photoelectric conversion elements SC-102 to 109>
In the organic photoelectric conversion element SC-101, the electron transport layer is changed to compounds 4, 3, 1, 26, 31, 9, 14, 41, respectively, instead of the compound 2, and the organic photoelectric conversion elements SC-102 to 109 are changed. Produced.

<Preparation of organic photoelectric conversion element SC-110>
In the organic photoelectric conversion element SC-101, the electron transport layer was changed to the compound (C) instead of the compound 2, and thus an organic photoelectric conversion element SC-110 was produced.

<Production of Organic Photoelectric Conversion Device SC-111 (Comparative)>
In the organic photoelectric conversion element SC-101, except that the electron transport layer is changed to bathocuproine (BCP) and a BCP layer having a film thickness of 10 nm is formed by vacuum deposition to form an electron transport layer, the organic photoelectric conversion element SC-101 Similarly, an organic photoelectric conversion element SC-111 was produced. The BCP was LUMO: -1.48 (eV), and the Tg was 287 ° C.

<Production of Comparative Organic Photoelectric Conversion Device SC-112>
In the comparative organic photoelectric conversion element SC-111, instead of a 0.5% 2,2,3,3-tetrafluoro-1-propanol solution of bathocuproine (BCP), 25 mmol / l of Ti-isopropoxide was added to ethanol. After the electrode portion was masked and spin-coated at 2000 rpm, it was taken out into the atmosphere and left for 60 minutes to hydrolyze Ti-isopropoxide to obtain a film thickness of 10 nm. A comparative organic photoelectric conversion element SC-112 was produced in the same manner except that a TiOx layer was formed and this was used as a hole blocking layer (electron transport layer). Although not an organic material, the energy levels were HOMO; -8.1 (eV), LUMO; -4.4 eV.

<Production of Organic Photoelectric Conversion Elements SC-113 and 114 (Comparative)>
In the organic photoelectric conversion element SC-111, a 10 nm-thick layer was similarly formed by a vacuum deposition method except that the electron transport layer was changed to bathocuproine (BCP) and changed to the comparative compounds (A) and (B). Organic photoelectric conversion elements SC-113 and 114 as electron transport layers were produced. The respective LUMO and Tg are also shown in Table 1.

For the obtained organic photoelectric conversion elements 101 to 110, the following conversion efficiency and open circuit voltage evaluation and durability evaluation were performed.

(Evaluation of conversion efficiency and fill factor)
Photoelectric conversion elements prepared above, was irradiated with light having an intensity of 100 mW / cm ² solar simulator (AM1.5G filter), a superposed mask in which the effective area 4.0 mm ² on the light receiving portion, the short circuit current density Jsc ( The four light-receiving portions formed on the same element were measured for mA / cm ² ), open-circuit voltage Voc (V), and fill factor (fill factor) FF, and the average value was obtained. Further, energy conversion efficiency η (%) was obtained from Jsc, Voc, and FF according to Equation 1.

Formula 1 Jsc (mA / cm ² ) × Voc (V) × FF = η (%)
(Durability evaluation)
A solar simulator (AM1.5G) was irradiated at an irradiation intensity of 100 mW / cm ² , voltage-current characteristics were measured, and initial conversion efficiency was measured. Further, assuming that the initial conversion efficiency at this time was 100, the conversion efficiency after 100 hours of irradiation with 100 mW / cm ² irradiation intensity with the resistance connected between the anode and the cathode was evaluated, and the relative reduction efficiency was calculated. .

Formula 2 Relative reduction efficiency (%) = (1−conversion efficiency after exposure / conversion efficiency before exposure) × 100
The LUMO value can also be obtained from photoelectron emission measurement (UPS) and UV-Vis spectrum measurement results. In the present invention, the LUMO value was obtained by molecular orbital calculation (B3LYP / 6-31G *).

The glass transition point (Tg) was measured using a differential scanning calorimeter, DSC-7 manufactured by PerkinElmer. The glass transition point was measured at an increase rate of 10 ° C./min, and was defined as the glass transition point at the intersection of the extended line of the baseline and the tangent line indicating the maximum slope from the peak rising portion to the peak apex.

It can be seen that the photoelectric conversion element according to the present invention has a large release voltage (Voc) and a high photoelectric conversion efficiency. Moreover, in durability evaluation, there is little fall of conversion efficiency and relative retention is high.

DESCRIPTION OF SYMBOLS 10 Bulk heterojunction type organic photoelectric conversion element 11 Substrate 12 Anode 13 Cathode 14 Photoelectric conversion layer 14 '1st photoelectric conversion part 15 Charge recombination layer 16 2nd photoelectric conversion part 17 Hole transport layer 18 Electron transport layer 20 Light Sensor array 21 Substrate 22 Anode 23 Cathode 24 Photoelectric conversion unit 24a Buffer layer 24b Photoelectric conversion layer

Claims

In an organic photoelectric conversion device having a cathode, an anode, and a bulk heterojunction photoelectric conversion layer in which a p-type semiconductor material and an n-type semiconductor material are mixed, an LUMO level is present between the cathode and the bulk heterojunction photoelectric conversion layer. An organic photoelectric conversion element comprising a layer containing a material shallower than −1.4 eV and having a Tg (glass transition temperature) of 50 ° C. or higher and 280 ° C. or lower.
2. The organic material according to claim 1, wherein the material constituting the layer between the cathode and the bulk heterojunction photoelectric conversion layer is a compound having at least a partial structure represented by the following general formula (1). Photoelectric conversion element.

(In the formula, each of Z 1 and Z 2 represents an atomic group that forms a substituted or unsubstituted aromatic heterocycle with a nitrogen atom.)
The organic photoelectric conversion according to claim 1 or 2, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (2). element.

(Wherein Z 1 and Z 3 each represent a group of atoms forming a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring together with —C═C—, and Z 2 and Z 4 each represent —C═C— (Represents a group of atoms forming a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring.)
4. The compound according to claim 1, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (3). The organic photoelectric conversion element as described.

(Wherein X 1 to X 7 represent a substituted or unsubstituted carbon atom or a nitrogen atom.)
5. The organic photoelectric conversion device according to claim 1, wherein the compound having a partial structure represented by the general formulas (1) to (3) is a low molecular compound.
6. The layer according to claim 1, wherein the layer containing a compound having a partial structure represented by the general formulas (1) to (3) is produced by a solution coating method. Organic photoelectric conversion element.
A solar cell comprising the organic photoelectric conversion element according to any one of claims 1 to 6.
An optical sensor array comprising the organic photoelectric conversion elements according to any one of claims 1 to 6 arranged in an array.