JP2021184408A - Photoelectric conversion element and composition for forming photoelectric conversion layer - Google Patents

Abstract

To provide a photoelectric conversion element having excellent durability and a composition for a photoelectric conversion layer.SOLUTION: There is provided a photoelectric conversion element in which a photoelectric conversion layer includes a surface treatment agent of a general formula (1) and semiconductor particles.SELECTED DRAWING: None

Description

The present invention relates to a photoelectric conversion element and a composition for forming a photoelectric conversion layer.

Photoelectric conversion elements that convert light energy into electrical energy are used in solar cells, photosensors, copiers, and the like. Of these, optical sensors that use near-infrared light as light energy are attracting attention for their use in night vision, ranging, security, semiconductor wafer inspection, and the like.

By the way, in recent years, it has been reported that semiconductor particles (quantum dots) such as PbS are used as materials for photoelectric conversion such as photoelectric conversion elements and solar cells. For example, Non-Patent Document 1 discloses that by substituting ethanedithiol for oleic acid around the semiconductor particles of PbSe, the semiconductor particles are brought closer to each other and the electrical conductivity is improved. Further, Patent Document 1 describes ultrafine particles in which a plurality of ultrafine particles such as CdS are bonded by a molecular chain such as benzenedithiol, and can be used for various purposes such as optical materials and electronic materials. It has been disclosed. Further, Patent Document 2 discloses that by substituting oleic acid around the semiconductor particles of PbSe with 2-aminoethane-1-thiol or the like, the semiconductor particles are closer to each other and a high photocurrent value can be obtained. Has been done.

Japanese Unexamined Patent Publication No. 7-60109 International Publication No. 2014/105353

J. M. Luther et al., "Structure, Optical, and Electrical Properties of Self-Assembled Films of PbSe Nanocrystals Treated with 2,

However, although the conventional technique can produce a photoelectric conversion element showing a high photocurrent value, there is a problem that the durability of the element over time is low. Therefore, an object to be solved by the present invention is to provide a photoelectric conversion element having excellent durability and a composition for forming a photoelectric conversion layer for obtaining the photoelectric conversion element.

［一般式（１）中、
Ｘ： 直接結合、又は分子量１４以上１５０以下の２価の連結基
Ｙ： ｍ＋１価の炭素数１の炭化水素基
Ｑ： スルファニル基、アルキルスルファニル基、又は硫黄原子を含有する１価の複素環基
Ｒ¹： 直接結合、イミノ基、酸素原子、又はＣＨ₂Ｏ
Ｒ²： 水素原子、アルキル基、ＮＲ³Ｒ⁴、又はアルコキシ基
Ｒ³及びＲ⁴： 各々独立して、アルキル基、又は水素原子
ｍ： １〜３の整数］ The present inventors have reached the present invention as a result of repeated diligent studies to solve the above problems.
That is, the present invention is a photoelectric conversion element having a photoelectric conversion layer between a pair of electrodes, wherein the photoelectric conversion layer contains a surface treatment agent represented by the following general formula (1) and semiconductor particles. The present invention relates to a photoelectric conversion element.

General formula (1)

[In general formula (1),
X: Direct bond or divalent linking group with a molecular weight of 14 or more and 150 or less Y: Hydrocarbon group with m + 1 valence and 1 carbon number Q: Sulfanyl group, alkylsulfanyl group, or monovalent heterocyclic group containing sulfur atom R ¹ : Direct bond, imino group, oxygen atom, or CH ₂ O
R ² : Hydrogen atom, alkyl group, NR ³ R ⁴ , or alkoxy group R ³ and R ⁴ : Independently each of the alkyl group or hydrogen atom m: an integer of 1 to 3]

The present invention also relates to the photoelectric conversion element in which the semiconductor particles include a compound semiconductor.

The present invention also relates to the photoelectric conversion element in which the semiconductor particles can absorb electromagnetic waves having a wavelength of 700 to 2500 nm.

Further, the present invention, the semiconductor particles, PbS, relates the photoelectric conversion element comprising one or more kinds selected from the group consisting of PbSe and Ag ₂ S.

The present invention also relates to a composition for forming a photoelectric conversion layer, which comprises a surface treatment agent represented by the above general formula (1) and semiconductor particles.

According to the present invention, a photoelectric conversion element having excellent durability can be obtained.

Hereinafter, embodiments of the present invention will be described.
<photoelectric conversion layer>
The photoelectric conversion layer contributes to charge separation and has a function of transporting electrons and holes generated by absorption of electromagnetic waves (mainly light) toward electrodes in opposite directions. The photoelectric conversion layer used in the present invention has a function of transporting electrons and holes. The conversion layer contains a surface treatment agent represented by the general formula (1) and semiconductor particles.

<Semiconductor particles>
The photoelectric conversion layer contains semiconductor particles. The semiconductor particles refer to particles made of semiconductors having an average particle size of 0.5 nm to 100 nm. From the viewpoint of improving stability and photoelectric conversion efficiency, the average particle size of the semiconductor particles is preferably 1 nm or more, more preferably 1.5 nm or more, still more preferably 2 nm or more, and improve film forming property and photoelectric conversion efficiency. From the viewpoint of allowing the particles to grow, it is preferably 20 nm or less, more preferably 10 nm or less. The particle size of the semiconductor particles in the present specification is a numerical value measured by observation with a transmission electron microscope. The semiconductor particles preferably contain compound semiconductors. The compound semiconductor consists of a group consisting of group 1 element, group 2 element, group 10 element, group 11 element, group 12 element, group 13 element, group 14 element, group 15 element, group 16 element and group 17 element. It is preferably a semiconductor composed of a compound containing at least two selected elements. It is preferable that the semiconductor particles can absorb electromagnetic waves having a wavelength of 700 to 2500 nm. An electromagnetic wave having a wavelength of 700 to 2500 nm is generally called near-infrared light (also referred to as near-infrared light), and in order for a semiconductor particle to absorb an electromagnetic wave having a wavelength of 700 to 2500 nm, the semiconductor particle has an electromagnetic wave having a wavelength of 700 to 2500 nm. It preferably contains a compound semiconductor that can be absorbed. Examples of the compound semiconductor capable of absorbing electromagnetic waves having a wavelength of 700 to 2500 nm include compound semiconductors having a perovskite crystal structure and metal chalcogenides (for example, oxides, sulfides, selenes, and tellurides). Specific examples of the compound semiconductor having a perovskite crystal structure include CH ₃ NH ₃ PbF ₃ , CH ₃ NH ₃ PbCl ₃ , CH ₃ NH ₃ PbBr ₃ , CH ₃ NH ₃ PbI ₃ , CsPbF ₃ , CsPbCl ₃ , and CsPbBr. ₃ , CsPbI ₃ , RbPbF ₃ , RbPbCl ₃ , RbPbBr ₃ , RbPbI ₃ , KPbF ₃ , KPbCl ₃ , KPbBr ₃ , KPbI _{3 and the} like. Specific examples of the metal chalcogenide include PbS, PbSe, PbTe, CdS, CdSe, CdTe, Sb ₂ S ₃ , Bi ₂ S ₃ , Ag ₂ S, Ag ₂ Se, Ag ₂ Te, Au ₂ S, and so on. Au ₂ Se, Au ₂ Te, Cu ₂ S, Cu ₂ Se, Cu ₂ Te, Fe ₂ S, Fe ₂ Se, Fe ₂ Te, In ₂ S 3, SnS, SnSe, SnTe, CuInS ₂ , CuInSe ₂ , CuInTe ₂ , EuS, EuSe, EuTe and the like. Among these, PbS, PbSe, Ag ₂ S is preferred.

<Surface treatment agent represented by the general formula (1)>
First, the substituent of the general formula (1) will be described.
The divalent linking group having a molecular weight of 14 or more and 150 or less in X is not particularly limited, but is preferably at least one group selected from the group consisting of an alkylene group, an oxyalkylene group, and a group to which these are bonded. preferable. The upper limit of the molecular weight of the divalent linking group is preferably 130 or less, more preferably 110 or less.

Examples of the alkylene group include an alkylene group such as a methylene group, an ethylene group and a hexylene group, which may be linear or branched. An alkylene group having 1 to 6 carbon atoms is preferable, and an alkylene group having 1 to 3 carbon atoms is more preferable.

Examples of the oxyalkylene group include an oxyalkylene group such as an oxymethylene group, an oxyethylene group and an oxyhexylene group, which may be linear or branched. An oxyalkylene group having 1 to 5 carbon atoms is preferable, and an oxyalkylene group having 1 to 3 carbon atoms is more preferable.

Examples of the alkyl group in the alkyl group in R ^{2 to R 4 and} the alkyl group in the alkyl sulfanyl group in Q include an alkyl group such as a methyl group, an ethyl group and a hexyl group, which may be linear or branched. good. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is particularly preferable.

Examples ^{of the alkoxy group in R 2} include an alkoxy group such as a methoxy group, an ethoxy group, and a hexyloxy group, which may be linear or branched. The alkoxy group is preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 3 carbon atoms, and particularly preferably a methoxy group.

Examples of the monovalent heterocyclic group containing a sulfur atom in Q include a thienyl group, a tetrahydrothienyl group, a tetrahydrothiopyranyl group, a thiazolyl group, a thiomorpholinyl group and the like. These may be substituted with an alkyl group. More preferably, it is a thienyl group or a tetrahydrothiopyranyl group. The Q is preferably a sulfanil group, an alkylsulfanil group, a thienyl group or a tetrahydrothiopyranyl group, and more preferably a sulfanil group.

Examples of the m + 1 valent hydrocarbon group having 1 carbon atom in Y include a methylene group and a methine group. m is an integer of 1 to 3, but 1 or 2 is preferable, and 1 is more preferable. That is, Y is preferably a methylene group.

In the embodiment of the general formula (1), R ¹ is a direct bond and R ² is an alkoxy group, or R ¹ is an oxygen atom or CH ₂ O and R ² is an alkyl group. Preferably, more preferably, R ¹ is an oxygen atom and R ² is an alkyl group. Hereinafter, specific examples of the surface treatment agent represented by the general formula (1) will be shown.

Further, the semiconductor particles may contain an organic ligand or a halogen element. Examples of the organic ligand include a carboxy group-containing compound, an amino group-containing compound, a sulfanyl group-containing compound, and a phosphino group-containing compound.

Examples of the carboxy group-containing compound include oleic acid, stearic acid, palmitic acid, myristic acid, lauric acid, and capric acid.

Examples of the amino group-containing compound include oleylamine, stearylamine, palmitylamine, myristylamine, laurylamine, caprylamine, octylamine, hexylamine, butylamine and the like.

Examples of the sulfanyl group-containing compound include ethanethiol, ethanedithiol, benzenethiol, benzenedithiol, decanethiol, decandithiol, and mercaptopropionic acid.

Examples of the phosphino group-containing compound include trioctylphosphine and tributylphosphine.

The halogen element is not particularly limited, and examples thereof include fluorine, chlorine, bromine, and iodine. The halogen element is preferably chlorine from the viewpoints of ease of manufacture of semiconductor particles, dispersion stability, versatility, cost, excellent performance development, and the like.

<photoelectric conversion element>
The photoelectric conversion element of the present invention has the above-mentioned photoelectric conversion layer between a pair of electrodes. In the photoelectric conversion element of the present invention, a known configuration of a photoelectric conversion element can be applied. Further, the photoelectric conversion element of the present invention can be manufactured by a known method except for the photoelectric conversion layer.

Here, a photoelectric conversion element that can be produced by using the composition for forming a photoelectric conversion layer of the present invention will be described in detail. Generally, a photoelectric conversion element using semiconductor particles is composed of at least a pair of electrodes and a photoelectric conversion layer. For the purpose of improving the photoelectric conversion efficiency, various types of device structures have been proposed depending on the energy matching between the electrode and the semiconductor particles and the method of manufacturing the photoelectric conversion layer composed of the semiconductor particles. For example, the photoelectric conversion layer forming composition of the present invention can be used to produce a photoelectric conversion element having the following known configurations.

1. 1. Schottky type photoelectric conversion element A photoelectric conversion element that obtains photovoltaic power by using a Schottky barrier formed at the interface between an electron-donating (p-type) or electron-accepting (n-type) semiconductor particle and an electrode. .. For example, when a p-type photoelectric conversion layer is used, a Schottky barrier is formed at the interface between the pair of electrodes and the electrode having the smaller internal work function, and charge separation occurs at the interface to perform photoelectric conversion. ..

2. 2. Bilayer heterojunction photoelectric conversion element Electron-donating (p-type) and electron-accepting (n-type) semiconductor particles and other semiconductor materials are individually formed between a pair of electrodes, and light charges are applied to the pn junction interface. It is a photoelectric conversion element that causes separation and obtains a photocurrent.

3. 3. Bulk heterojunction type photoelectric conversion element An organic semiconductor layer is formed by mixing electron-donating (p-type) and electron-accepting (n-type) semiconductor particles and other semiconductor materials at an arbitrary ratio between a pair of electrodes. At this time, the p-type and n-type materials may be uniformly dispersed or non-uniform. Since photocharge separation occurs at the interface formed by each p-type material and n-type material, it is possible to form a wider pn junction than the bilayer heterojunction type.

<Electrode>
It is preferable that at least one of the pair of electrodes constituting the photoelectric conversion element transmits light. Specific examples include conductive metal oxides such as tin oxide, zinc oxide, indium oxide, and indium tin oxide (ITO), or gold, silver, platinum, chromium, nickel, lithium, indium, aluminum, calcium, and magnesium. And the like, and examples thereof include a mixture or a laminate of these metals and a conductive metal oxide.

The electrode is generally flat, but may be corrugated, pyramidal, comb-shaped or the like in order to improve energy conversion efficiency. As a method for forming these electrodes, a general electrode forming method can be used, and a PVD method such as a vacuum vapor deposition method, a sputtering method, and an ion plating method, a CVD method, a chemical reaction method (sol-gel method, etc.), and casting can be used. Examples thereof include a method, a spray coating method, an inkjet method, and a spin coating method.

The photoelectric conversion element may include a layer other than the photoelectric conversion layer between the pair of electrodes, and has a hole injection layer, a hole transport layer, an electron transport layer, and / or an electron injection layer. May be good.

<Hole injection layer>
For the hole injection layer, a hole injection material that exhibits an excellent hole injection effect on the photoelectric conversion layer and can form a hole injection layer having excellent adhesion to the anode interface and thin film formation is used. .. Further, when such a material is laminated in multiple layers and a material having a high hole injection effect and a material having a high hole transport effect are laminated in multiple layers, the materials used for each are referred to as a hole injection material and a hole transport material. Sometimes. These hole injection materials and hole transport materials need to have a large hole mobility and a small ionization energy of usually 5.5 eV or less. As such a hole injection layer, a material that transports holes to the light emitting layer with a lower electric field strength is preferable, and further ^{, when an electric field with a hole mobility of, for example, 10 4} to 10 ⁶ V / cm is applied, at least. It is preferably 10 ^-6 cm ² / V · sec. The hole injecting material and the hole transporting material are not particularly limited as long as they have the above-mentioned preferable properties, and are conventionally used as a hole charge transporting material in an optical transmission material or an organic EL element. Any known material used for the hole injection layer can be selected and used.

Examples of such a hole injecting material and a hole transporting material include a triazole derivative (see US Pat. No. 3,112,197) and an oxadiazole derivative (see US Pat. No. 3,189,447). ), Imidazole derivative (see Japanese Patent Publication No. 37-1609, etc.), polyarylalkane derivative (US Pat. Nos. 3,615,402, 3,820,989, 3,542,544). No. 45-555, No. 51-10983, No. 51-93224, No. 55-17105, No. 56-4148, No. 55-108667, No. 55-15953A, 56-36656, etc.), Pyrazoline derivative and Pyrazolone derivative (US Pat. Nos. 3,180,729, 4,278,746, JP-A-55- No. 88064, No. 55-88065, No. 49-105537, No. 55-51086, No. 56-80051, No. 56-88141, No. 57-45545, No. 54-112637. No. 55-74546, etc.), phenylenediamine derivatives (US Pat. Nos. 3,615,404, Japanese Patent No. 51-10105, No. 46-3712, No. 47-25336). , JP-A-54-53435, JP-A-541-10536, JP-A-54-119925, etc.), arylamine derivatives (US Pat. Nos. 3,567,450, 3,180,703). No. 3, 240,597, No. 3,658,520, No. 4,232,103, No. 4,175,961, No. 4,175,961 4,012,376, Japanese Patent Publication No. 49-35702, Japanese Patent Application Laid-Open No. 59-27577, Japanese Patent Application Laid-Open No. 55-144250, Japanese Patent Application Laid-Open No. 56-119132, Japanese Patent Publication No. 56-22437, Western German Patent No. Disclosed in 1,110,518, etc.), amino-substituted calcon derivatives (see US Pat. No. 3,526,501, etc.), oxazole derivatives (see US Pat. No. 3,257,203, etc.) ), Styrylanthracene derivative (see JP-A-56-46234, etc.), fluorenone derivative (see JP-A-54-110837, etc.), Hydrazone derivative (US Pat. Kaisho 54-59143, Gaz. 55-520 See No. 63, No. 55-52064, No. 55-46760, No. 55-85495, No. 57-11350, No. 57-148949, No. 2-311591, etc.). Stilbene Derivatives (Japanese Patent Laid-Open No. 61-210363, No. 61-228451, No. 61-14642, No. 61-72255, No. 62-47646, No. 62-36674, No. 62. See -10652, 62-30255, 60-93455, 60-94462, 60-174749, 60-175052, etc.), stilbene derivatives (US Patent No. 4). , 950, 950), Polysilane-based (Japanese Patent Laid-Open No. 2-204996), Aniline-based copolymer (Japanese Patent Laid-Open No. 2-282263), Conductiveness disclosed in JP-A 1-211399. Examples thereof include polymer oligomers (particularly thiophene oligomers).

Further, as a hole injection material and a hole transport material, a porphyrin compound (Japanese Patent Laid-Open No. 63-2956965), an aromatic tertiary amine compound and a styrylamine compound (US Pat. No. 4,127,412). Japanese Patent Laid-Open Nos. 53-27033, 54-58445, 54-149634, 54-64299, 55-79450, 55-144250, 56-119132. , No. 61-295558, No. 61-98353, No. 63-295695, etc.) can also be used. For example, 4,4'-bis (N- (1-naphthyl) -N-phenylamino) biphenyl having two fused aromatic rings in the molecule described in US Pat. No. 5,061,569, etc. , 4,4', 4 "-tris (N- (3-methylphenyl) -N-phenyl" in which three triphenylamine units described in JP-A-4-308688 are linked in a starburst type. Amino) Triphenylamine and the like can be mentioned. Further, phthalocyanine derivatives such as copper phthalocyanine and hydrogen phthalocyanine can be mentioned as the hole injection material. Further, aromatic dimethylidene compounds, p-type Si, p-type SiC and the like can be mentioned. Inorganic compounds can also be used as hole injection materials and hole transport materials.

Further, materials that can be used for the hole injection layer include molybdenum oxide (MnO _x ), vanadium oxide (VO _x ), ruthenium oxide (RuO _x ), copper oxide (CuO _x ), tungsten oxide (WO _x ), and iridium oxide. Inorganic oxides such as (IrO _x ) and their dopes are also mentioned.

Specific examples of the aromatic tertiary amine compound include, for example, N, N'-diphenyl-N, N'-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine, N, N, N', N'-(4-methylphenyl) -1,1'-phenyl-4,4'-diamine, N, N, N', N'-(4-methylphenyl) -1,1'-Biphenyl-4,4'-diamine, N, N'-diphenyl-N, N'-dinaphthyl-1,1'-biphenyl-4,4'-diamine, N, N'-(methylphenyl) -N, N'-(4-n-butylphenyl) -phenanthrene-9,10-diamine, N, N-bis (4-di-4-tolylaminophenyl) -4-phenyl-cyclohexane, N, N'-bis ( 4'-diphenylamino-4-biphenylyl) -N, N'-diphenylbenzidine, N, N'-bis (4'-diphenylamino-4-phenyl) -N, N'-diphenylbenzidine, N, N'- Bis (4'-diphenylamino-4-phenyl) -N, N'-di (1-naphthyl) benzidine, N, N'-bis (4'-phenyl (1-naphthyl) amino-4-phenyl) -N , N'-diphenylbenzidine, N, N'-bis (4'-phenyl (1-naphthyl) amino-4-phenyl) -N, N'-di (1-naphthyl) benzidine and the like, which are positive. It can be used for both hole injection materials and hole transport materials.
Tables 3 and 4 show particularly preferable examples of the hole injection material.

In order to form the hole injection layer, the above-mentioned compound is thinned by a known method such as a vacuum deposition method, a spin coating method, a casting method, or a Langmuir-Bloget method (LB method). The film thickness of the hole injection layer is not particularly limited, but is usually 5 nm to 5 μm.

<Electron injection layer>
For the electron injection layer, an electron injection material that exhibits an excellent electron injection effect on the photoelectric conversion layer and can form an electron injection layer having excellent adhesion to the cathode interface and thin film forming property is used. Examples of such electron-injected materials include metal complex compounds, nitrogen-containing five-membered ring derivatives, fluorenone derivatives, anthraquinodimethane derivatives, diphenoquinone derivatives, thiopyrandioxide derivatives, perylenetetracarboxylic acid derivatives, fleolenilidenemethane. Examples thereof include derivatives, anthron derivatives, silol derivatives, triarylphosphin oxide derivatives, polyquinolin and its derivatives, polyquinoxalin and its derivatives, polyfluorene and its derivatives, calcium acetylacetonate, sodium acetate and the like. Inorganic / organic composite materials in which a metal such as cesium is doped with vasophenanthroline (Proceedings of the Society of Polymer Science, Vol. 50, No. 4, p. 660, published in 2001) and the 50th Joint Lecture on Applied Physics. Proceedings of the lecture, No. BCP, TPP, T5MPyTZ, etc. described on page 3, 1402, published in 2003 are also given as examples of electron injection materials, but they can form a thin film necessary for device fabrication, inject electrons from the cathode, and transport electrons. As long as it is a material, it is not particularly limited to these.

Among the electron-injected materials, preferred examples include a metal complex compound, a nitrogen-containing five-membered ring derivative, a silol derivative, and a triarylphosphine oxide derivative. As a preferable metal complex compound, a metal complex of 8-hydroxyquinoline or a derivative thereof is suitable. Specific examples of the metal complex of 8-hydroxyquinoline or a derivative thereof include tris (8-hydroxyquinolinate) aluminum, tris (2-methyl-8-hydroxyquinolinate) aluminum, and tris (4-methyl-8-). Hydroxyquinolinate) Aluminum, Tris (5-Methyl-8-Hydroxyquinolinate) Aluminum, Tris (5-phenyl-8-Hydroxyquinolinate) Aluminum, Bis (8-Hydroxyquinolinate) (1-naphtholat) ) Aluminum, bis (8-hydroxyquinolinate) (2-naphtholat) Aluminum, bis (8-hydroxyquinolinate) (phenorate) aluminum, bis (8-hydroxyquinolinate) (4-cyano-1-naphtholate) ) Aluminum, bis (4-methyl-8-hydroxyquinolinate) (1-naphtholate) aluminum, bis (5-methyl-8-hydroxyquinolinate) (2-naphtholate) aluminum, bis (5-phenyl-8) -Hydroxyquinolinate) (phenorate) aluminum, bis (5-cyano-8-hydroxyquinolinate) (4-cyano-1-naphtholate) aluminum, bis (8-hydroxyquinolinate) chloroaluminum, bis (8) -Aluminum complex compounds such as hydroxyquinolinate (o-cresolate) aluminum, tris (8-hydroxyquinolinate) gallium, tris (2-methyl-8-hydroxyquinolinate) gallium, tris (4-methyl- 8-Hydroxyquinolinate) gallium, tris (5-methyl-8-hydroxyquinolinate) gallium, tris (2-methyl-5-phenyl-8-hydroxyquinolinate) gallium, bis (2-methyl-8) -Hydroxyquinolinate) (1-naphtholate) gallium, bis (2-methyl-8-hydroxyquinolinate) (2-naphtholate) gallium, bis (2-methyl-8-hydroxyquinolinate) (phenorate) gallium , Bis (2-methyl-8-hydroxyquinolinate) (4-cyano-1-naphtholate) gallium, bis (2,4-dimethyl-8-hydroxyquinolinate) (1-naphtholate) gallium, bis (2) , 5-Dimethyl-8-Hydroxyquinolinate) (2-naphtholate) gallium, bis (2-methyl-5-phenyl-8-hydroxyquinolinate) (phenorate) gallium, bis (2-methyl-5-cy) Anno-8-hydroxyquinolinate) (4-cyano-1-naphtholate) gallium, bis (2-methyl-8-hydroxyquinolinate) chlorogallium, bis (2-methyl-8-hydroxyquinolinate) ( In addition to gallium complex compounds such as o-cresolate) gallium, 8-hydroxyquinolinate lithium, bis (8-hydroxyquinolinate) copper, bis (8-hydroxyquinolinate) manganese, bis (10-hydroxybenzo [h] ] Kinolinate) Metal complex compounds such as berylium, bis (8-hydroxyquinolinate) zinc, and bis (10-hydroxybenzo [h] quinolinate) zinc can be mentioned.

Preferable nitrogen-containing five-membered ring derivatives include oxadiazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, and triazole derivatives, and specifically, 2,5-bis (1-phenyl) -1, 3,4-Oxadiazole, 2,5-bis (1-phenyl) -1,3,4-thiazole, 2,5-bis (1-phenyl) -1,3,4-oxadiazole, 2- (4) '-Tert-butylphenyl) -5- (4 "-biphenyl) 1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1,3,4-oxadiazole, 1,4 -Bis [2- (5-phenyloxadiazolyl)] benzene, 1,4-bis [2- (5-phenyloxadiazolyl) -4-tert-butylbenzene], 2- (4'-tert-butyl Benzene) -5- (4 "-biphenyl) -1,3,4-thiadiazole, 2,5-bis (1-naphthyl) -1,3,4-thiadiazole, 1,4-bis [2- (5- (5-) Phenylthiazolyl)] Benzene, 2- (4'-tert-butylphenyl) -5- (4 "-biphenyl) -1,3,4-triazole, 2,5-bis (1-naphthyl) -1, Examples thereof include 3,4-triazole and 1,4-bis [2- (5-phenyltriazolyl)] benzene.

Further, examples of the material that can be used for the electron injection layer include _{inorganic oxides such as zinc oxide (ZnO x} ) and titanium oxide (TiO _x ) and their doped bodies.

Specific examples of particularly preferable oxadiazole derivatives, triazole derivatives and siror derivatives are shown in Tables 5 to 7. In addition, Ph in the table represents a phenyl group.

(Oxadiazole derivative)

(Triazole derivative)

(Siror derivative)

The photoelectric conversion element may include other constituent members in addition to the respective layers. For example, an optical film (filter) that does not transmit ultraviolet rays may be provided. Ultraviolet rays have high energy and contribute to deterioration of organic materials. By blocking this ultraviolet ray, the life of the element can be extended.

A protective film may be provided for the purpose of protecting the photoelectric conversion layer from an external impact. The protective film is, for example, a polymer film such as styrene resin, epoxy resin, acrylic resin, polyurethane, polyimide, polyvinyl alcohol, polyvinylidene fluoride, polyethylene polyvinyl alcohol copolymer, or an inorganic oxide film such as silicon oxide, silicon nitride, or aluminum oxide. It can be made of a nitride film, a metal plate such as aluminum or a metal foil, or a laminated film thereof. As the material of these protective films, only one kind may be used, or two or more kinds may be used.

It is generally said that semiconductor particles are deteriorated by moisture and oxygen in the air. A barrier membrane may be provided to prevent this. For example, metals or inorganic oxides are preferable, and Ti, Al, Mg, Zr, silicon oxide, aluminum oxide, silicon oxide, aluminum oxide, magnesium oxide, zinc oxide, indium oxide, tin oxide, yttrium oxide, boron oxide, etc. Calcium oxide and the like can be mentioned. There is no particular order in which these various functional films are laminated, and a functional film having these functions may be used.

Hereinafter, the present invention will be specifically described based on examples. Unless otherwise specified, "part" means "part by mass" and "%" means "% by mass". Unless otherwise specified, all measurements were performed at 25 ° C. Table 8 shows the structure of the surface treatment agent used in the comparative example.

<Preparation of semiconductor particles PbS-0>
First, as a sulfur source solution, 0.40 part of elemental sulfur and 6.0 parts of oleylamine were heated to 120 ° C. in a nitrogen atmosphere in a reaction vessel to form a uniform solution, and then cooled to 25 ° C. Next, as a lead source solution, 0.32 parts of lead chloride and 6.0 parts of oleylamine were heated to 120 ° C. in another reaction vessel under a nitrogen atmosphere. Then, after preparing the lead source solution at 40 ° C., 1.8 parts of the above sulfur source solution was added at once. After reacting for 30 seconds, the container was immersed in an ice bath and rapidly cooled, and then diluted with 13 parts of hexane. After centrifuging (4000 rpm, 5 minutes) to remove unreacted raw materials, add 12 parts of a mixed solution of butanol: methanol = 2: 1 (volume ratio) to precipitate the semiconductor particles and centrifuge (4000 rpm). 5 minutes) to recover the semiconductor particles. Then, 24 parts of a mixed solution consisting of hexane: oleic acid = 1: 2 (volume ratio) was added, and the mixture was stirred for 30 minutes, centrifuged, and the supernatant was recovered. Semiconductor particle sedimentation, redispersion, and impurity sedimentation are repeated twice, and finally the semiconductor particles are precipitated and vacuum dried, and then adjusted to a solid content concentration of 5% using n-octane to obtain semiconductor particles PbS-0. (Average particle size 3.5 nm).

<Semiconductor particle PbSe-0 synthesis>
As a lead source solution, 0.22 parts of lead oxide, 0.73 parts of oleic acid, and 10 parts of 1-octadecene were heated to 150 ° C. in a reaction vessel under a nitrogen atmosphere. Then, a mixture consisting of 2.5 parts of 1M trioctylphosphine-selenium solution and 0.028 parts of diphenylphosphine was quickly added, the reaction solution was heated to 180 ° C., kept at 160 ° C., and reacted for 2 minutes. , The reaction solution was quenched. After diluting with 10 parts of hexane, it was precipitated with acetone. The precipitate was washed with acetone 5 times and vacuum dried to obtain semiconductor particles PbSe-0 (average particle size 2.7 nm).

<Semiconductor fine particles Ag ₂ S-0 synthesis>
0.04 parts of silver oleate, 8 parts of octanethiol, and 4 parts of dodecylamine were heated in a reaction vessel at 200 ° C. for 0.5 hours in an Ar atmosphere. After allowing this solution to cool to room temperature, 40 parts of absolute ethanol was added. The obtained mixture was centrifuged and vacuum dried to obtain semiconductor particles Ag ₂ S-0 (average particle size 2.5 nm).

<Preparation of composition for forming photoelectric conversion layer>
<Example 1>
Semiconductor particles PbS-0 were prepared in a toluene solution having a solid content concentration of 1%. After mixing 1 part of the prepared solution and 1 part of the toluene solution of 5% surface treatment agent 1, the mixture was stirred for 12 hours. Purification was performed by the reprecipitation method using toluene and ethanol. The precipitate was vacuum dried to prepare a photoelectric conversion forming composition PbS-1 as a 5 wt% solution of n-octane.

<Examples 2 to 22, Comparative Examples 1 to 8>
_{PbS-2 to 24, PbSe-1 to 3, and Ag 2} S-1 to 3 were prepared in the same manner as in Example 1 except that the surface treatment agent 1 was changed to the surface treatment agent shown in Table 9. Of these, PbS-2 to 18, PbSe-1 and 2, Ag ₂ S-1 and 2 are the compositions for forming a photoelectric conversion layer of the present invention, and PbS-19 to 24, PbSe-3, Ag ₂ S. -3 is a composition that is not the composition for forming a photoelectric conversion layer of the present invention.

<Example 1>
(Manufacturing of photoelectric conversion element)
The production and evaluation of the photoelectric conversion element will be described below. The vapor deposition was ^{carried out in a vacuum of 10-6} Torr under the condition that the temperature was not controlled such as heating and cooling of the substrate. The evaluation of the element was measured using a photoelectric conversion element having an element area of 2 mm × 2 mm. First, spin PEDOT / PSS (poly (3,4-ethylenedioxy) -2.5-thiophene / polystyrene sulfonic acid, CLEVIOUS (registered trademark) PVP CH8000 manufactured by Heraeus) on a cleaned glass plate with ITO electrode. It was coated by a coating method and dried at 110 ° C. for 20 minutes to obtain a hole injection layer having a thickness of 35 nm. The composition for forming a photoelectric conversion layer PbS-1 was applied onto the hole injection layer by a spin coating method to form a photoelectric conversion layer having a thickness of 150 nm. Next, a ZnO dispersion N-10 manufactured by Avantama was formed on the photoelectric conversion layer by spin coating to form an electron transport layer having a thickness of 50 nm. Next, aluminum (hereinafter referred to as Al) was vapor-deposited on the electron transport layer to a thickness of 200 nm to form an electrode, and a photoelectric conversion element was obtained.

(Evaluation of photoelectric conversion element)
The durability of the obtained device was evaluated by the method shown below. Durability was calculated by measuring the IV curve before and after storage of the element and calculating the ratio. The IV curve of the cell uses xenon lamp white light as a light source (PEC-L01 manufactured by Pexel Technologies Co., Ltd.) and is light at a light intensity (100 mW / cm ² ) equivalent to sunlight (AM1.5). Under a mask with an irradiation area of 0.0363 cm ² (2 mm square), a scanning speed of 0.1 V / sec (0.01 Vstep) using an IV characteristic measuring device (PECK2400-N, manufactured by Pexel Technologies Co., Ltd.). The measurement was performed under the conditions of a waiting time of 50 msec after setting the voltage, a measurement integration time of 50 msec, a start voltage of −0.1 V, and an end voltage of 1.1 V. For durability, the IV curve was measured before storage (immediately after device fabrication) and after storage of the photoelectric conversion element for 4 days under the conditions of shading, 25 ° C., and humidity of 60%, and before storage (immediately after device fabrication). It was calculated as the ratio of the conversion efficiency after storage to the conversion efficiency of.
(Evaluation criteria)
⊚: Ratio 95% or more: Good ○: Ratio 90% or more and less than 95%: Practically usable △: Ratio 80% or more and less than 90%: Practically unusable ×: Ratio less than 80%: Defective

<Examples 2 to 22>
The photoelectric conversion element was used in the same manner as in Example 1 except that PbS-2 to 18, PbSe-1 to 2 and Ag _{2 S-1 to 2 were used instead of PbS-1 used in Example 1.} Each was prepared and evaluated. The results are shown in Table 10.

<Comparative Examples 1 to 8>
Instead of PbS-1 used in Example 1, prepared PbS-19~24, PbSe-3, Ag is ₂ S-3 a except for using each in the same manner as in Example 1 a photoelectric conversion element, respectively, evaluation bottom. The results are shown in Table 10.

It has been clarified that all of the photoelectric conversion elements (Examples 1 to 22) of the present invention are superior in durability over time to the elements of the comparative examples. The surface treatment agents 1 to 18 used in Examples 1 to 22 can be adsorbed on the surface of carbonyl group semiconductor particles, and as a result, deterioration due to oxygen, water, etc. is suppressed, and the durability of the device is improved. It is speculated that it may be. In Examples 1 to 3 and 13 to 15, particularly high durability was observed. This is because the surface treatment agents 1 to 3 and 13 to 15 all have an acetoxy group, and in addition to the effect of adsorbing at multiple points on the semiconductor particles, oxygen and water are formed by closely arranging the semiconductor particles. It is speculated that the approach could be further suppressed.

Claims (5)

A photoelectric conversion element having a photoelectric conversion layer between a pair of electrodes, wherein the photoelectric conversion layer contains a surface treatment agent represented by the following general formula (1) and semiconductor particles.

General formula (1)

[In general formula (1),
X: Direct bond or divalent linking group with a molecular weight of 14 or more and 150 or less Y: Hydrocarbon group with m + 1 valence and 1 carbon number Q: Sulfanyl group, alkylsulfanyl group, or monovalent heterocyclic group containing sulfur atom R ¹ : Direct bond, imino group, oxygen atom, or CH ₂ O
R ² : Hydrogen atom, alkyl group, NR ³ R ⁴ , or alkoxy group R ³ and R ⁴ : Independently each of the alkyl group or hydrogen atom m: an integer of 1 to 3] The photoelectric conversion element according to claim 1, wherein the semiconductor particles include a compound semiconductor. The photoelectric conversion element according to claim 1 or 2, wherein the semiconductor particles can absorb electromagnetic waves having a wavelength of 700 to 2500 nm. Semiconductor particles, PbS, PbSe and Ag ₂ is selected from the group consisting of S comprising one or more kinds according to claim 2 or 3 photoelectric conversion device according. A composition for forming a photoelectric conversion layer, which comprises a surface treatment agent represented by the following general formula (1) and semiconductor particles.
General formula (1)

[In general formula (1),
X: Direct bond or divalent linking group with a molecular weight of 14 or more and 150 or less Y: Hydrocarbon group with m + 1 valence and 1 carbon number Q: Sulfanyl group, alkylsulfanyl group, or monovalent heterocyclic group containing sulfur atom R ¹ : Direct bond, imino group, oxygen atom, or CH ₂ O
R ² : Hydrogen atom, alkyl group, NR ³ R ⁴ , or alkoxy group R ³ and R ⁴ : Independently each of the alkyl group or hydrogen atom m: an integer of 1 to 3]