JP2018006622A - Photoelectric conversion element and solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element that hinders a voltage decrease even in a high temperature environment and enables a secondary battery to be satisfactorily charged without depending on temperature environment.SOLUTION: A photoelectric conversion element comprises a base plate 1, a first electrode 2, a hole blocking layer 3, an electron transport layer 4, a photosensitization compound 5 adsorbed on a surface of the electron transport layer 4, a hole transport layer 6, and a second electrode 7. The hole transport layer 6 contains a basic compound A such as 4-pyrrolidinopyridine, and an ionic compound B such as lithium bis(fluoromethane sulfonyl)imide.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photoelectric conversion element and a solar cell.

In recent years, the driving power in electronic circuits has become very small, and it has become possible to drive various electronic components such as sensors even with weak power. Furthermore, when utilizing sensors, application to a self-supporting power source (environmental power generation element) that can generate and consume on the spot is expected. Among them, solar cells are attracting attention as elements that can generate power anywhere if there is light.
Among solar cells, it is known that solid-state dye-sensitized solar cells have a significantly reduced power generation due to crystallization of the hole transport layer in a high temperature environment. Therefore, it has been proposed to suppress crystallization by increasing steric hindrance, for example, by introducing an alkyl group into the molecular skeleton of the hole transport material (see, for example, Non-Patent Document 1).
In order to drive the electronic component, the power generation element needs to exhibit a certain voltage or more, and a decrease in power generation (particularly a decrease in voltage) can cause a drive failure of the electronic component.

  An object of the present invention is to provide a photoelectric conversion element and a solar cell that suppress a voltage drop even under a high temperature environment and can charge a good secondary battery independent of the temperature environment. In addition, the said high temperature environment means that temperature is 40 degreeC or more and 90 degrees C or less, for example.

  The photoelectric conversion element of the present invention as a means for solving the problems includes a substrate, a first electrode, a hole blocking layer, an electron transport layer, and a photosensitizing compound adsorbed on the surface of the electron transport layer. A hole transport layer and a second electrode, wherein the hole transport layer is composed of a basic compound A represented by the following general formula (1) and an ionicity represented by the following general formula (2). Compound B.

(Wherein R ₁ and R ₂ each independently represents an alkyl group or an aromatic hydrocarbon group and represent the same or different groups, or R ₁ and R ₂ are bonded to each other and contain a nitrogen atom) Represents a heterocyclic group.)

(In the formula, X ⁺ represents a counter cation.)

  According to the present invention, it is possible to provide a photoelectric conversion element and a solar battery that can suppress a voltage drop even under a high temperature environment and can charge a good secondary battery independent of the temperature environment.

It is a schematic sectional drawing showing an example of the structure of the photoelectric conversion element which concerns on this invention. It is a figure for demonstrating the secondary battery charging circuit used in the Example.

  Hereinafter, a photoelectric conversion element and a solar cell according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art, and any aspect is possible. As long as the functions and effects of the present invention are exhibited, the scope of the present invention is included.

FIG. 1 is a schematic sectional view showing an example of the structure of a photoelectric conversion element according to the present invention.
In the embodiment shown in FIG. 1, the first electrode 2 is formed on the substrate 1, the hole blocking layer 3 is formed on the first electrode 2, the electron transport layer 4 is formed on the hole blocking layer 3, An example of a configuration in which the photosensitizing compound 5 is adsorbed on the electron transport layer 4 and the hole transport layer 6 is sandwiched between the first electrode 2 and the second electrode 7 facing the first electrode 2 is illustrated. In FIG. 1, lead lines 8 and 9 are provided so that the first electrode 2 and the second electrode 7 are electrically connected. Details will be described below.

<Board>
The substrate 1 used in the present invention is not particularly limited, and a known substrate can be used. The substrate 1 is preferably made of a transparent material, and examples thereof include glass, a transparent plastic plate, a transparent plastic film, and an inorganic transparent crystal.

<First electrode>
The first electrode 2 used in the present invention is not particularly limited as long as it is a conductive material that is transparent to visible light, and is a known one that is used for ordinary photoelectric conversion elements, liquid crystal panels, and the like. Can be used.
Examples of the material of the first electrode 2 include indium oxide doped with tin (hereinafter also referred to as “ITO”) and tin oxide doped with fluorine (hereinafter also referred to as “FTO”). And tin oxide doped with antimony (hereinafter sometimes referred to as “ATO”), indium / zinc oxide, niobium / titanium oxide, graphene, and the like. These may be used alone or in combination of two or more.
There is no restriction | limiting in particular as average thickness of said 1st electrode 2, Although it can select suitably according to the objective, 5 nm or more and 100 micrometers or less are preferable, and 50 nm or more and 10 micrometers or less are more preferable.
The first electrode 2 is preferably provided on a substrate 1 made of a material transparent to visible light in order to maintain a certain hardness. Examples of the substrate 1 include glass, a transparent plastic plate, A transparent plastic film, an inorganic transparent crystal, or the like is used.
For example, FTO-coated glass, ITO-coated glass, zinc oxide: aluminum-coated glass, FTO-coated transparent plastic film, ITO-coated transparent can be used. A plastic film etc. are mentioned.
In addition, a transparent electrode obtained by doping tin oxide or indium oxide with cations or anions having different valences, a metal electrode having a structure capable of transmitting light, such as a mesh shape or a stripe shape, on a substrate such as a glass substrate But you can.
These may be used singly or as a mixture of two or more kinds or laminated ones. Further, for the purpose of reducing the resistance, a metal lead wire or the like may be used in combination.
Examples of the material of the metal lead wire include metals such as aluminum, copper, silver, gold, platinum, and nickel. The metal lead wire can be formed by a method in which deposition is performed on the substrate by vapor deposition, sputtering, pressure bonding, or the like, and ITO or FTO is provided thereon.

<Hole blocking layer>
In general, the hole blocking layer 3 used in the present invention suppresses power reduction due to recombination (so-called reverse electron transfer) of holes in the electrolyte and electrons on the electrode surface when the electrolyte is in contact with the electrode. Provided. The effect of the hole blocking layer 3 is particularly remarkable in a solid dye-sensitized solar cell. Compared with a wet dye-sensitized solar cell using an electrolyte, a solid dye-sensitized solar cell using an organic hole transport material or the like regenerates holes in the hole transport material and electrons on the electrode surface. This is due to the high bonding (reverse electron transfer) speed.
The material of the hole blocking layer 3 is not particularly limited as long as it is transparent to visible light and is an electron transporting material, and can be appropriately selected according to the purpose. For example, titanium oxide, niobium oxide , Magnesium oxide, aluminum oxide, zinc oxide, tungsten oxide, tin oxide and the like. These may be used singly or in combination of two or more, but may be laminated or mixed, but titanium oxide is particularly preferable.
The method for forming the hole blocking layer 3 is not particularly limited and can be appropriately selected. However, in order to suppress the loss current in room light, a high internal resistance is required, and the film forming method is also important. is there. In general, a sol-gel method for forming a wet film can be mentioned, but the film current is low and the loss current cannot be sufficiently suppressed. For this reason, dry film formation such as sputtering is more preferable, which is advantageous in that the film density is sufficiently high and loss current can be suppressed.
The average thickness of the hole blocking layer 3 is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5 nm or more and 1 μm or less, and more preferably 500 nm or more and 700 nm or less in wet film formation, and dry film formation. Then, 10 nm or more and 30 nm or less are more preferable.

<Electron transport layer>
The electron transport layer 4 is disposed on the hole blocking layer 3 and is generally configured as a porous layer, and includes an electron transport material such as semiconductor particles.
The electron transport layer may be a single layer or a multilayer. In the case of multiple layers, a dispersion of semiconductor particles having different particle diameters may be applied in multiple layers, or different types of semiconductors, and application layers having different compositions of resins and additives may be applied in multiple layers. Multi-layer coating is an effective means when the average thickness is insufficient with a single coating.
As the film thickness of the electron transport layer 4 increases, the amount of supported photosensitizing material per unit projected area also increases, so that the light capture rate increases. However, the diffusion distance of injected electrons also increases, so charge recombination Loss also increases. Therefore, the average thickness of the electron transport layer 4 is preferably 100 nm to 100 μm, more preferably 100 nm to 50 μm, and still more preferably 100 nm to 10 μm.

The semiconductor particles are not particularly limited, and known ones can be used. For example, a single semiconductor such as silicon or germanium, a compound semiconductor typified by a metal chalcogenide, or a compound having a perovskite structure is used. Can be mentioned.
Metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxides, cadmium, zinc, lead, silver, antimony, bismuth. Sulfide, cadmium, lead selenide, cadmium telluride and the like.
Other compound semiconductors are preferably phosphides such as zinc, gallium, indium, cadmium, gallium arsenide, copper-indium-selenide, copper-indium-sulfide, and the like.
As the compound having a perovskite structure, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate and the like are preferable.
Among these, oxide semiconductors are preferable, and titanium oxide, zinc oxide, tin oxide, and niobium oxide are particularly preferable. These may be used alone or in combination of two or more. The crystal type of these semiconductors is not particularly limited, and may be single crystal, polycrystal, or amorphous.
There is no restriction | limiting in particular as an average particle diameter of the primary particle of the said semiconductor particle, Although it can select suitably according to the objective, 1-100 nm is preferable and 5-50 nm is more preferable.
The efficiency may be improved by mixing or laminating semiconductor particles having an average particle size larger than the average particle size to scatter incident light. In this case, the average particle size is preferably 50 to 500 nm.

There is no restriction | limiting in particular as a preparation method of the said electron carrying layer 4, According to the objective, it can select suitably, For example, the method of forming a thin film in vacuum, such as sputtering, the wet film forming method etc. are mentioned.
Among these, from the viewpoint of production cost, a wet film forming method is preferable, a paste in which the powder or sol of the semiconductor particles is dispersed is prepared, and the hole on the first electrode 2 as the electron collector electrode substrate or the hole is prepared. The method of apply | coating on the blocking layer 3 is more preferable.
The wet film forming method is not particularly limited, and a known method can be used. For example, a dipping method, a spray method, a wire bar method, a spin coating method, a roller coating method, a blade coating method, a gravure coating method, etc. Is mentioned. Furthermore, as a wet printing method, for example, various methods such as letterpress, offset, gravure, intaglio, rubber plate, and screen printing can be used.

When the semiconductor particle dispersion is prepared by mechanical pulverization using a mill or the like, it is formed by dispersing at least the semiconductor particles alone or a mixture of the semiconductor particles and the resin in a solvent.
Examples of the resin include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid ester, and methacrylic acid ester, silicon resin, phenoxy resin, polysulfone resin, polyvinyl butyral resin, polyvinyl formal resin, and polyester resin. , Cellulose ester resin, cellulose ether resin, urethane resin, phenol resin, epoxy resin, polycarbonate resin, polyarylate resin, polyamide resin, polyimide resin and the like. These may be used individually by 1 type and may use 2 or more types together.
Examples of the solvent include alcohol solvents such as water, methanol, ethanol, isopropyl alcohol, and α-terpineol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ethyl formate, ethyl acetate, and n-butyl acetate. Ester solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, or N-methyl-2-pyrrolidone Solvent, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, Halogenated hydrocarbon solvents such as 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, Examples thereof include hydrocarbon solvents such as m-xylene, p-xylene, ethylbenzene, and cumene. These may be used individually by 1 type and may use 2 or more types together.
In order to prevent re-aggregation of the particles, the semiconductor particle paste obtained by the dispersion of the semiconductor particles or the sol-gel method is prepared by using an acid such as hydrochloric acid, nitric acid, acetic acid, or polyoxyethylene (10) octylphenyl ether. A surfactant such as acetylacetone, a chelating agent such as 2-aminoethanol, and ethylenediamine may be added.
It is also an effective means to add a thickener for the purpose of improving the film forming property.
Examples of the thickener include polymers such as polyethylene glycol and polyvinyl alcohol, and ethyl cellulose.

The semiconductor particles may be subjected to firing, microwave irradiation, electron beam irradiation, or laser beam irradiation in order to bring the particles into electronic contact with each other after coating and to improve film strength and adhesion to the substrate. preferable. These treatments may be performed singly or in combination of two or more.
When firing the semiconductor particles, the firing temperature is not particularly limited and may be appropriately selected depending on the intended purpose. However, if the temperature is raised excessively, the resistance of the substrate may increase or melt. In this respect, 30 ° C. or higher and 700 ° C. or lower is preferable, and 100 ° C. or higher and 600 ° C. or lower is more preferable. Moreover, there is no restriction | limiting in particular as baking time, Although it can select suitably according to the objective, 10 minutes or more and 10 hours or less are preferable.
When the semiconductor particles are irradiated with microwaves, the semiconductor particles may be irradiated from the surface side where the electron transport layer 4 is formed, or may be irradiated from the surface side where the electron transport layer is not formed. There is no restriction | limiting in particular as irradiation time, Although it can select suitably according to the objective, 1 hour or less is preferable.
For the purpose of increasing the surface area of the semiconductor particles after firing the semiconductor particles and increasing the efficiency of electron injection from the photosensitizing compound described later to the semiconductor particles, for example, an aqueous solution of titanium tetrachloride or a mixed solution with an organic solvent is used. Chemical plating used or electrochemical plating using a titanium trichloride aqueous solution may be performed.
A film in which the semiconductor particles having a diameter of several tens of nm are stacked by sintering or the like forms a porous state. This nanoporous structure has a very high surface area, which can be expressed using a roughness factor.
The roughness factor is a numerical value representing the actual area inside the porous with respect to the area of the semiconductor particles applied to the substrate. Therefore, the roughness factor is preferably as large as possible, but is preferably 20 or more from the relationship with the average thickness of the electron transport layer 4.

<Photosensitizing compound>
In order to further improve the photoelectric conversion efficiency, the photosensitizing compound 5 may be adsorbed on the surface of the electron transport layer 4.
The photosensitizing compound 5 is not particularly limited as long as it is a compound that is photoexcited by the excitation light used, and known compounds can be used, and specific examples include the following compounds.
The metal complex compounds described in JP-T-7-500630, JP-A-10-233238, JP-A 2000-26487, JP-A 2000-323191, JP-A 2001-59062, etc. 10-93118, JP-A No. 2002-164089, JP-A No. 2004-95450, J. Pat. Phys. Chem. C, 7224, Vol. 111 (2007), etc., JP 2004-95450 A, Chem. Commun. , 4887 (2007), etc., JP-A No. 2003-264010, JP-A No. 2004-63274, JP-A No. 2004-115636, JP-A No. 2004-200068, JP-A No. 2004-235052. J. et al. Am. Chem. Soc. , 12218, Vol. 126 (2004), Chem. Commun. , 3036 (2003), Angew. Chem. Int. Ed. , 1923, Vol. 47 (2008), etc .; Am. Chem. Soc. 16701, Vol. 128 (2006), J.M. Am. Chem. Soc. , 14256, Vol. 128 (2006), JP-A-11-86916, JP-A-11-214730, JP-A-2000-106224, JP-A-2001-76773, JP-A-2003-7359. And the merocyanine dyes described in JP-A-11-214731, JP-A-11-238905, JP-A-2001-52766, JP-A-2001-76775, JP-A-2003-7360, etc. 9-arylxanthene compounds described in JP-A-10-92477, JP-A-11-273754, JP-A-11-273755, JP-A-2003-3273, etc., JP-A-10-93118, Triarylmethane compounds described in Japanese Unexamined Patent Publication No. 2003-31273, JP-A-9- 99744, JP-A No. 10-233238, JP-A No. 11-204821, JP-A No. 11-265738, J. Phys. Chem. , 2342, Vol. 91 (1987), J. MoI. Phys. Chem. B, 6272, Vol. 97 (1993), Electroanaly. Chem. , 31, Vol. 537 (2002), JP-A-2006-032260, J. Pat. Porphyrins Phthalocyanines, 230, Vol. 3 (1999), Angew. Chem. Int. Ed. , 373, Vol. 46 (2007), Langmuir, 5436, Vol. 24 (2008) etc., and the phthalocyanine compound, porphyrin compound, etc. can be mentioned. Among these, it is preferable to use a metal complex compound, a coumarin compound, a polyene compound, an indoline compound, and a thiophene compound. D131 represented by the following structural formula (1) manufactured by Mitsubishi Paper Industries, Ltd., and the following structural formula (2) D102 represented, and D358 represented by the following structural formula (3) are more preferable.

As a method of adsorbing the photosensitizing compound 5 to the electron transport layer 4, a method of immersing an electron current collecting electrode having the electron transport layer 4 in a photosensitizing compound solution or a dispersion, a photosensitizing compound solution For example, a method of applying the medium or the dispersion liquid to the electron transport layer 4 and adsorbing it can be used.
In the case of dipping the electron current collecting electrode having the electron transport layer 4 in a photosensitizing compound solution or dispersion, a dipping method, a dipping method, a roller method, an air knife method, or the like can be used.
In the case of a method in which a photosensitizing compound solution or dispersion is applied to the electron transport layer 4 and adsorbed, a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, a spray method, or the like is used. Can do.
Further, it may be adsorbed in a supercritical fluid using carbon dioxide or the like.
When adsorbing the photosensitizing compound 5 to the electron transport layer 4, a condensing agent may be used in combination.
The condensing agent has a catalytic action that physically or chemically binds the photosensitizing compound to the surface of the electron transport layer, or acts stoichiometrically to favorably move the chemical equilibrium. Any of those to be made may be used.
Furthermore, a thiol or a hydroxy compound may be added as a condensation aid.

Examples of the solvent for dissolving or dispersing the photosensitizing compound include water, methanol, ethanol, alcohol solvents such as isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ethyl formate, acetic acid, and the like. Ester solvents such as ethyl or n-butyl acetate, ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, or N-methyl- Amide solvents such as 2-pyrrolidone, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenze , Halogenated hydrocarbon solvents such as bromobenzene, iodobenzene or 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene , Hydrocarbon solvents such as o-xylene, m-xylene, p-xylene, ethylbenzene, and cumene. These may be used individually by 1 type and may use 2 or more types together.
Depending on the type of the photosensitizing compound, there are compounds that work more effectively when the aggregation between the compounds is suppressed. Therefore, an aggregating and dissociating agent may be used in combination.
The aggregating / dissociating agent is not particularly limited and may be appropriately selected depending on the photosensitizing compound to be used. A steroid compound such as cholic acid or chenodeoxycholic acid, a long-chain alkyl carboxylic acid or a long-chain alkyl phosphonic acid may be used. preferable.
The addition amount of the aggregating and dissociating agent is preferably 0.01 parts by mass or more and 500 parts by mass or less, and more preferably 0.1 parts by mass or more and 100 parts by mass or less with respect to 1 part by mass of the photosensitizing compound.
The temperature for adsorbing the photosensitizing compound, or the photosensitizing compound and the aggregation / dissociation agent to the electron transport layer 4 is preferably −50 ° C. or higher and 200 ° C. or lower.
The adsorption time is preferably from 5 seconds to 1,000 hours, more preferably from 10 seconds to 500 hours, and even more preferably from 1 minute to 150 hours.
The adsorption is preferably performed in a dark place. Moreover, the said adsorption | suction may be performed still and may be performed, stirring.
The stirring is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method using a stirrer, ball mill, paint conditioner, sand mill, attritor, disperser, ultrasonic dispersion and the like.

<Hole transport layer>
Examples of the material for the hole transport layer 6 include an electrolytic solution obtained by dissolving a redox couple in an organic solvent, a gel electrolyte obtained by impregnating a polymer matrix obtained by dissolving a redox couple in an organic solvent, and a molten salt containing the redox couple. , Solid electrolytes, inorganic hole transport materials, organic hole transport materials, and the like. Among these, an organic hole transport material is preferable.
In addition, although there exists a part demonstrated below as an example for an organic hole transport material, it is not restricted to this.
The hole transport layer 6 may have a single layer structure made of a single material or a laminated structure made of a plurality of compounds. When the hole transport layer has a laminated structure, it is preferable to use a polymer material for the hole transport layer close to the second electrode 7. By using a polymer material having excellent film forming properties, the surface of the porous electron transport layer 4 can be further smoothed, and the photoelectric conversion characteristics can be improved.
In addition, since the polymer material does not easily penetrate into the porous electron transport layer, it is excellent in covering the surface of the porous electron transport layer, and is effective in preventing a short circuit when an electrode is provided. Therefore, higher performance can be obtained.

As the organic hole transport material used when the hole transport layer has a single layer structure, a known organic hole transport compound is used.
Specific examples thereof include oxadiazole compounds disclosed in Japanese Patent Publication No. 34-5466, triphenylmethane compounds disclosed in Japanese Patent Publication No. 45-555, Japanese Patent Publication No. 52-4188, and the like. Pyrazoline compounds shown in JP-A-55-42380, hydrazone compounds shown in JP-A-56-123544, oxadiazole compounds shown in JP-A-56-123544, etc., JP-A-54-58445 Examples thereof include tetraarylbenzidine compounds disclosed in Japanese Laid-Open Patent Publications, and stilbene compounds disclosed in Japanese Patent Laid-Open Nos. 58-65440 and 60-98437.

  As the organic hole transport material, an organic hole transport material represented by the following general formula (3) is preferable. The organic hole transport material represented by the following general formula (3) is preferably contained in an amount of 32 to 99% by mass, and more preferably 71 to 92% by mass with respect to the entire hole transport layer 6.

(In the formula, R ₃ represents a hydrogen atom or a methyl group.)

Among them, Adv., Wherein R ₃ is a hydrogen atom. Mater. , 813, vol. 17, (2005), (2,2 ′, 7,7′-tetrakis (N, N-di-p-methoxyphenylamine) -9,9′-spirobifluorene: spiro-OMeTAD) is preferable, R The hole transport material (HTM1) described in Non-Patent Document 1 in which ₃ is a methyl group is more preferable.
The spiro-OMeTAD has a high hole mobility, and two benzidine skeleton molecules are twisted and bonded. For this reason, an electron cloud close to a sphere is formed, and excellent photoelectric conversion characteristics are exhibited due to good hopping conductivity between molecules. In addition, since it is highly soluble and soluble in various organic solvents and is amorphous (amorphous substance having no crystal structure), it is easy to be densely packed in the porous electron transport layer, and is a solid type dye-sensitized solar cell Has useful properties. Further, since it does not have a light absorption characteristic of 450 nm or more, the photosensitizing compound can efficiently absorb light, and has a characteristic useful for a solid dye-sensitized solar cell.
The HTM1 has useful properties such as introduction of an alkyl group into the molecular skeleton to increase steric hindrance and thereby suppress crystallization in a high temperature environment.
The average thickness of the hole transport layer 6 is not particularly limited and may be appropriately selected depending on the intended purpose. However, the hole transport layer 6 preferably has a structure that enters the pores of the porous electron transport layer. The thickness is preferably 0.01 μm or more and more preferably 0.1 μm or more and 10 μm or less on the layer.

A known hole transporting polymer material is used as the polymer material used when the hole transporting layer 6 has a laminated structure and disposed near the second electrode 7.
Specific examples thereof include, for example, poly (3-n-hexylthiophene), poly (3-n-octyloxythiophene), poly (9,9′-dioctyl-fluorene-co-bithiophene), poly (3,3 '''-Didodecyl-quarterthiophene), poly (3,6-dioctylthieno [3,2-b] thiophene), poly (2,5-bis (3-decylthiophen-2-yl) thieno [3,2 -B] thiophene), poly (3,4-didecylthiophene-co-thieno [3,2-b] thiophene), poly (3,6-dioctylthieno [3,2-b] thiophene-co-thieno [ 3,2-b] thiophene), poly (3,6-dioctylthieno [3,2-b] thiophene-co-thiophene), poly (3.6-dioctylthieno [3,2-b] thiophene-co- Bithio Polythiophene compounds such as phen),
Poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene], poly [2-methoxy-5- (3,7-dimethyloctyloxy) -1,4-phenylenevinylene], poly [( 2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene) -co- (4,4′-biphenylene-vinylene)] and the like,
Poly (9,9′-didodecylfluorenyl-2,7-diyl), poly [(9,9-dioctyl-2,7-divinylenefluorene) -alt-co- (9,10-anthracene)] , Poly [(9,9-dioctyl-2,7-divinylenefluorene) -alt-co- (4,4′-biphenylene)], poly [(9,9-dioctyl-2,7-divinylenefluorene) -Alt-co- (2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene)], poly [(9,9-dioctyl-2,7-diyl) -co- (1,4- (2,5-dihexyloxy) benzene)] and the like,
Polyphenylene compounds such as poly [2,5-dioctyloxy-1,4-phenylene] and poly [2,5-di (2-ethylhexyloxy-1,4-phenylene];
Poly [(9,9-dioctylfluorenyl-2,7-diyl) -alt-co- (N, N′-diphenyl) -N, N′-di (p-hexylphenyl) -1,4-diamino Benzene], poly [(9,9-dioctylfluorenyl-2,7-diyl) -alt-co- (N, N′-bis (4-octyloxyphenyl) benzidine-N, N ′-(1, 4-diphenylene)], poly [(N, N′-bis (4-octyloxyphenyl) benzidine-N, N ′-(1,4-diphenylene)]], poly [(N, N′-bis (4- (2-Ethylhexyloxy) phenyl) benzidine-N, N ′-(1,4-diphenylene)], poly [phenylimino-1,4-phenylenevinylene-2,5-dioctyloxy-1,4-phenylenevinylene- 1,4-phenylene], poly p-tolylimino-1,4-phenylenevinylene-2,5-di (2-ethylhexyloxy) -1,4-phenylenevinylene-1,4-phenylene], poly [4- (2-ethylhexyloxy) phenylimino- 1,4-biphenylene] and other polyarylamine compounds,
Poly [(9,9-dioctylfluorenyl-2,7-diyl) -alt-co- (1,4-benzo (2,1 ′, 3) thiadiazole], poly (3,4-didecylthiophene- Mention may be made of polythiadiazole compounds such as co- (1,4-benzo (2,1 ′, 3) thiadiazole).
Among these, polythiophene compounds and polyarylamine compounds are particularly preferable from the viewpoint of carrier mobility and ionization potential.

Various additives may be added to the organic hole transport material.
Examples of the additive include iodine, lithium iodide, sodium iodide, potassium iodide, cesium iodide, calcium iodide, copper iodide, iron iodide, silver iodide and other metal iodides,
Quaternary ammonium salts such as tetraalkylammonium iodide, pyridinium iodide, metal bromides such as lithium bromide, sodium bromide, potassium bromide, cesium bromide, calcium bromide,
Bromine salts of quaternary ammonium compounds such as tetraalkylammonium bromide and pyridinium bromide,
Metal chlorides such as copper chloride and silver chloride, metal acetates such as copper acetate, silver acetate and palladium acetate,
Metal sulfates such as copper sulfate and zinc sulfate, metal complexes such as ferrocyanate-ferricyanate, ferrocene-ferricinium ion,
Sulfur compounds such as sodium polysulfide, alkylthiol-alkyldisulfides,
Viologen dye, hydroquinone, 1,2-dimethyl-3-n-propylimidazolinium iodide, 1-methyl-3-n-hexylimidazolinium iodide, 1,2-dimethyl-3-ethylimidazo Inorg. Such as lithium trifluoromethanesulfonate, 1-methyl-3-butylimidazolium nonafluorobutylsulfonate, 1-methyl-3-ethylimidazolium bis (trifluoromethyl) sulfonylimide. Chem. 35 (1996) 1168, basic compounds such as pyridine, 4-t-butylpyridine, benzimidazole,
Examples include ionic compounds such as lithium trifluoromethanesulfonylimide and lithium diisopropylimide.
The basic compound is considered to exist mainly at the interface in the vicinity of the electron transport layer, and is considered to suppress reverse electron transfer from the electron transport layer (electron transfer from the electron transport layer to the hole transport layer). The cation of the ionic compound is considered to be mainly present at the interface near the electron transport layer, and the anion is considered to be doped in the hole transport layer. In a high temperature environment, control of the contact interface between the hole transport layer and the electron transport layer (and the photosensitizing compound) is important as well as control of crystallization of the hole transport layer itself. It is thought that the voltage drop is caused by a short circuit at the contact interface, an increase in resistance, a defect in the hole conduction path due to crystallization, and the like.

  In the present invention, it is preferable to add to the hole transport layer 6 a basic compound A represented by the following general formula (1) and an ionic compound B represented by the following general formula (2) as additives. . As a result, the internal resistance of the photoelectric conversion element is increased, so that a loss current in weak light such as room light can be reduced, a higher open-circuit voltage can be obtained, and the crystal of the hole transport layer can be obtained in a high temperature environment. This is advantageous in that the reduction in voltage is suppressed because the contact interface between the electron transport layer and the hole transport layer is kept good.

In the formula, each of R ₁ and R ₂ independently represents an alkyl group or an aromatic hydrocarbon group, and represents the same or different group, or R ₁ and R ₂ are bonded to each other and contain a nitrogen atom. Represents a cyclic group. The alkyl group, aromatic hydrocarbon group, and heterocyclic group may have a substituent. R ₁ and R ₂ are preferably a heterocyclic group containing a nitrogen atom, and particularly preferably a 5-membered ring containing a nitrogen atom.

  The basic compound A represented by the general formula (1) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, in the following structural formulas (1-1) to (1-9) And the like.

  In addition, when there is a number next to the above structural formula, the number means a compound number in the chemical substance database “Japanese Chemical Substance Dictionary” published by the Japan Science and Technology Agency.

Conventionally, the compound itself represented by the structural formula (1-1), which is the basic compound A represented by the general formula (1), is known. Some of these compounds are known to be used as basic compounds in liquid dye-sensitized solar cells using iodine electrolyte.
However, when the basic compound is used in a conventional liquid dye-sensitized solar cell using an iodine electrolyte, the open-circuit voltage is high, but the short-circuit current density is greatly reduced, and the photoelectric conversion characteristics are significantly deteriorated. It has been known.

  When the basic compound A represented by the general formula (1) is used in the solid dye-sensitized solar cell using the organic hole transport material as the material for the hole transport layer, the amount of decrease in the short circuit current density is small. Excellent photoelectric conversion characteristics can be obtained by obtaining a high open circuit voltage. Furthermore, in photoelectric conversion in weak light such as room light, which has few reports, a particularly significant advantage appears.

  The content of the basic compound A represented by the general formula (1) in the hole transport layer is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the organic hole transport material. More preferably, they are 5 to 15 mass parts.

(In the formula, X ⁺ represents a counter cation.)

  X in the ionic compound B represented by the general formula (2) is preferably a heterocyclic compound containing nitrogen such as imidazolium or pyrrolidinium, an alkali metal such as Li, Na, or K, and more preferably Li.

  Examples of the ionic compound B having a heterocyclic compound as a counter cation include 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide, 1-methyl-1-propylpyrrolidinium bis (fluorosulfonyl) imide, and the like. Can be mentioned.

Conventionally, the ionic compound B itself represented by the general formula (2) is known and used as an additive for the purpose of improving the conductivity by ionizing a neutral conductive organic substance. Has been reported (see, for example, JP-A-2014-229359).
However, even when the ionic compound B represented by the general formula (2) is used in combination with the basic compound A represented by the general formula (1), the electron transport layer 4 is used in a high temperature environment. In addition, the control of the contact interface between the hole transport layer 6 and the hole transport layer 6 is insufficient, and a short circuit and an increase in resistance cannot be sufficiently suppressed.
By using both the basic compound A represented by the general formula (1) and the ionic compound B represented by the general formula (2), the hole transport layer 6 can be crystallized in a high temperature environment. And the contact interface between the electron transport layer 4 and the hole transport layer 6 is kept good, so that the voltage drop can be suppressed.

  The molar ratio of the basic compound A to the ionic compound B in the hole transport layer 6 is preferably A: B = 1: 0.1 to 1: 1, and A: B = 1: 0.1. More preferably, it is ˜1: 0.5.

Moreover, you may add the oxidizing agent for making a part of organic hole transport material into a radical cation for the purpose of improving electroconductivity.
Examples of the oxidizing agent include tris (4-bromophenyl) aminium hexachloroantimonate, silver hexafluoroantimonate, nitrosonium tetrafluorate, silver nitrate, and a cobalt complex compound.
It is not necessary for all organic hole transport materials to be oxidized by the addition of the oxidizing agent, and only a part of the hole transporting material needs to be oxidized. The added oxidizing agent may be taken out of the system after the addition or may not be taken out.

The hole transport layer 6 forms a hole transport layer directly on the electron transport layer 4 having a photosensitizing compound adsorbed on its surface. There is no restriction | limiting in particular in the preparation methods of the hole transport layer 6, The method of forming a thin film in vacuum, such as vacuum deposition, and the wet film forming method are mentioned. In consideration of the manufacturing cost and the like, a wet film forming method is particularly preferable, and a method of coating on the electron transport layer 4 is preferable.
When this wet film-forming method is used, the coating method is not particularly limited and can be performed according to a known method. For example, dip method, spray method, wire bar method, spin coating method, roller coating method, blade coating method, gravure coating method, and wet printing methods such as relief printing, offset, gravure, intaglio printing, rubber printing, screen printing, etc. Can be used. Alternatively, the film may be formed in a supercritical fluid or a subcritical fluid having a temperature and pressure lower than the critical point.

The supercritical fluid exists as a non-aggregating high-density fluid in a temperature / pressure region that exceeds the limit (critical point) at which gas and liquid can coexist, and does not aggregate even when compressed. As long as the fluid is in the above state, there is no particular limitation, and it can be appropriately selected according to the purpose.
Examples of the supercritical fluid include carbon monoxide, carbon dioxide, ammonia, nitrogen, water, methanol, ethanol, n-butanol and other ercol solvents, ethane, propane, 2,3-dimethylbutane, benzene, toluene and the like. Hydrocarbon solvents, halogen solvents such as methylene chloride and chlorotrifluoromethane, and ether solvents such as dimethyl ether are preferred. Among these, carbon dioxide is particularly preferable because it has a critical pressure of 7.3 MPa and a critical temperature of 31 ° C., so that it can easily create a supercritical state and is nonflammable and easy to handle.
These fluids may be used alone or in combination of two or more.
The subcritical fluid is not particularly limited as long as it exists as a high pressure liquid in a temperature and pressure region near the critical point, and can be appropriately selected according to the purpose.
The compound mentioned as a supercritical fluid mentioned above can be used conveniently also as a subcritical fluid.
The critical temperature and critical pressure of the supercritical fluid are not particularly limited and can be appropriately selected according to the purpose. However, the critical temperature is preferably −273 ° C. or more and 300 ° C. or less, particularly 0 ° C. or more and 200 ° C. or less. preferable.
Furthermore, in addition to the above supercritical fluid and subcritical fluid, an organic solvent or an entrainer can be used in combination.
By adding an organic solvent and an entrainer, the solubility in the supercritical fluid can be adjusted more easily.
There is no restriction | limiting in particular as such an organic solvent, According to the objective, it can select suitably.
For example, a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone,
Ester solvents such as ethyl formate, ethyl acetate, or n-butyl acetate,
Ether solvents such as diisopropyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane;
Amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, or N-methyl-2-pyrrolidone,
Halogenated hydrocarbon solvents such as dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, iodobenzene, or 1-chloronaphthalene,
Hydrocarbons such as n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene or cumene System solvents and the like.

In this invention, after providing the hole transport layer 6 on the 1st electrode 2 which provided the electron carrying layer 4 which adsorb | sucked the photosensitizing compound, you may give a press process process.
By performing this press treatment, the organic hole transport material is more closely attached to the porous electrode, so that the efficiency is improved.
Although there is no restriction | limiting in particular in a press processing method, The roll molding method using the press molding method using a flat plate represented by IR tablet shaping device, a roller, etc. can be mentioned.
The pressure is preferably 10 kgf / cm ² (0.98 MPa) or more, and more preferably 30 kgf / cm ² (2.94 MPa) or more. Although there is no restriction | limiting in particular in the time to press, It is preferable to carry out within 1 hour. Further, heat may be applied during the pressing process.
In the above pressing process, a release material may be sandwiched between the press and the electrode.
Examples of the release material include polytetrafluoroethylene, polychlorotrifluoride ethylene, tetrafluoroethylene hexafluoropropylene copolymer, perfluoroalkoxy fluoride resin, polyvinylidene fluoride, ethylene tetrafluoride ethylene copolymer, ethylene Examples thereof include fluororesins such as chlorotrifluoride ethylene copolymer and polyvinyl fluoride.

A metal oxide may be provided between the hole transport layer 6 and the second electrode 7 after the press treatment step and before providing the counter electrode. Examples of the metal oxide that may be provided include molybdenum oxide, tungsten oxide, vanadium oxide, and nickel oxide, and molybdenum oxide is particularly preferable.
The method for providing these metal oxides on the hole transport layer 6 is not particularly limited, and examples thereof include a method of forming a thin film in a vacuum such as sputtering and vacuum deposition, and a wet film forming method.
In the wet film forming method, a method in which a paste in which a metal oxide powder or sol is dispersed is prepared and applied onto the hole transport layer 6 is preferable.
When this wet film-forming method is used, the coating method is not particularly limited, and can be performed according to a known method.
For example, dip method, spray method, wire bar method, spin coating method, roller coating method, blade coating method, gravure coating method, and wet printing methods such as relief printing, offset, gravure, intaglio printing, rubber printing, screen printing, etc. Can be used. The film thickness is preferably from 0.1 to 50 nm, more preferably from 1 to 10 nm.

<Second electrode>
The second electrode 7 can be formed on the hole transport layer 6 or on the metal oxide in the hole transport layer 6. In addition, the second electrode 7 can be generally the same as the first electrode 2, and a support is not necessarily required in a configuration in which strength and sealability are sufficiently maintained.
Examples of the material of the second electrode 7 include metals such as platinum, gold, silver, copper, and aluminum, carbon compounds such as graphite, fullerene, carbon nanotube, and graphene, and conductive metal oxides such as ITO, FTO, and ATO. , Conductive polymers such as polythiophene and polyaniline.
There is no restriction | limiting in particular as a film thickness of said 2nd electrode 7, According to the objective, it can select suitably, 1 type may be used individually and 2 or more types may be used together.
About formation of said 2nd electrode 7, it can form by methods, such as application | coating, lamination, vapor deposition, CVD, bonding, on a hole transport layer suitably according to the kind of material used and the kind of said hole transport layer.
In the photoelectric conversion element of the present invention, at least one of the first electrode 2 and the second electrode 7 must be substantially transparent. In the present invention, it is preferable that the first electrode 2 is transparent and incident light is incident from the first electrode 2 side. In this case, a material that reflects light is preferably used on the second electrode 7 side, and a metal, glass, plastic, or metal thin film on which a conductive oxide is deposited is preferable. It is also effective to provide an antireflection layer on the incident light incident side.

<Application>
In the present invention, the photoelectric conversion element refers to an element that converts light energy into electric energy or an element that converts electric energy into light energy. Specific examples include a solar cell or a photodiode. preferable.
The photoelectric conversion element of the present invention can be applied to a power supply device by combining with a circuit board for controlling the generated current. Examples of the equipment using the power supply device include an electronic desk calculator and a wristwatch. In addition, the power supply device having the photoelectric conversion element of the present invention can be applied to a mobile phone, an electronic notebook, electronic paper, and the like. Moreover, the power supply device which has the photoelectric conversion element of this invention can also be used as an auxiliary power supply for extending the continuous use time of a rechargeable or dry battery type electric appliance. Furthermore, it can be used as an alternative to a primary battery combined with a secondary battery as a self-supporting power source for sensors.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, embodiment of this invention is not limited to these Examples.

Example 1
<Preparation of titanium oxide semiconductor electrode (electron transport layer)>
By reactive sputtering with oxygen gas using a target made of titanium metal, the ITO conductive film as the first electrode 2 is placed on the glass substrate as the substrate 1 and the titanium oxide is densely formed on the integrated ITO coated glass. A hole blocking layer 3 was formed.
The first electrode 2 was laser-etched with a laser device to form a 10-cell series substrate.
Next, 3 g of titanium oxide (P90, manufactured by Nippon Aerosil Co., Ltd.), 0.2 g of acetylacetone, and 0.3 g of a surfactant (polyoxyethylene octylphenyl ether, manufactured by Wako Pure Chemical Industries, Ltd.) were added to 5.5 g of water and ethanol. A bead mill treatment was performed for 12 hours together with 1.0 g to obtain a titanium oxide dispersion. A paste was prepared by adding 1.2 g of polyethylene glycol (# 20,000, manufactured by Wako Pure Chemical Industries, Ltd.) to the obtained titanium oxide dispersion.
The obtained paste was applied on the hole blocking layer 3 so as to have an average thickness of 1.5 μm, dried at room temperature, and then baked at 500 ° C. for 30 minutes in the air to obtain a porous electron transport layer 4. Formed. Thus, a titanium oxide semiconductor electrode was produced.

<Production of photoelectric conversion element>
The titanium oxide semiconductor electrode was immersed in D358 (0.5 mM, acetonitrile / t-butanol (volume ratio 1: 1) solution) manufactured by Mitsubishi Paper Industries Co., Ltd. represented by the following structural formula (3), and darkened for 1 hour. Then, the photosensitizing compound 5 was adsorbed by allowing it to stand.

  Next, an organic hole transport material (9,9 '-([1,1'-biphenyl] -4,4'-diyl) bis (N3, N3, N6, N6-) represented by the following structural formula (4) tetrakis (4-methoxyphenyl) -9H-carbazole-3,6-diamine): X51, Dyenamo): 183.8 mg of chlorobenzene solution: 1 mL of basic compound A represented by the following structural formula (1-3) ( 4-Pyrrolidinopyridine: PyP, Tokyo Chemical Industry Co., Ltd.): 22.98 mg is added, and ionic compound B (1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide, Kishida Chemical Co., Ltd.): 22.70 mg. In addition, a hole transport layer coating solution was prepared (molar ratio A: B = 1: 0.52).

Next, the hole transport layer 6 was formed by spin coating the hole transport layer coating solution on the semiconductor electrode carrying the photosensitizing compound. Thus, a photoelectric conversion layer was formed.
Next, using a mask patterned so as to be in series with 10 cells on the photoelectric conversion layer, silver was vacuum-deposited to a thickness of 100 nm to form a second electrode.

<Evaluation of photoelectric conversion element>
The obtained photoelectric conversion element was connected to the secondary battery charging circuit shown in FIG.
In FIG. 2, reference numeral 11 denotes a photoelectric conversion element. Reference numeral 12 denotes a power management integrated circuit (PMIC) that outputs a stabilized power source necessary for an external circuit from a power source output from the photoelectric conversion element 11. Reference numeral 13 denotes a circuit that operates with a power source output from the PMIC, and includes a sensor and a communication circuit. Reference numeral 14 denotes a secondary battery, and the secondary battery is charged by the environmental power supply while the stabilized output of the PMIC outputs a specified voltage.

The LTC3331 manufactured by Linear Technology is used as the PMIC, the output voltage of the PMIC is set to 3.0V, and the lockout voltage setting of the PMIC is set to 7V at the rising edge and 6V at the falling edge. The secondary battery is charged when the PMIC outputs a voltage of 3.0 V ± 3% and the photoelectric conversion element outputs 6.0 V or more.
To confirm the charging of the secondary battery, the voltage of the secondary battery was observed with a data logger (midi LOGGER GL900, Graphtec Co., Ltd.).

After circuit connection, it was left under high temperature environment (85 ° C.) under white LED irradiation (1,000 Lux: 0.24 mW / cm ² ) for 500 hours, and under white LED irradiation (1,000 Lux: 0.24 mW / cm ² ). The chargeability to the secondary battery was evaluated (indicated as “when charging is possible”, “when charging is possible and the voltage is 7 V or more”, “when charging is not possible” and “×”).
Moreover, the photoelectric conversion characteristic (open circuit voltage Voc) of the solar cell was also evaluated, and the results are shown in Table 1.
For the measurement of photoelectric conversion characteristics, a high color rendering LED desk lamp (CDS-90α, a desk lamp manufactured by Cosmo Techno Co., Ltd .; study mode) is used as a white LED, and a solar cell evaluation system (As-510-PV03, NF Circuit Design Block Co., Ltd.) was used. The results before heating are also shown in Table 1.

Example 2
A photoelectric conversion device was prepared and evaluated in the same manner as in Example 1 except that the ionic compound B in Example 1 was changed to lithium bis (fluorosulfonyl) imide (LiFSI, Kishida Chemical Co., Ltd.). The results are shown in Table 1.

Example 3
A photoelectric conversion device was prepared and evaluated in the same manner as in Example 1 except that the basic compound A in Example 1 was changed to 4-Dimethylaminopyridine (DMAP, Tokyo Chemical Industry Co., Ltd.). The results are shown in Table 1.

Example 4
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the hole transport material in Example 1 was changed to an organic hole transport material (H101, Dyesol) represented by the following structural formula (5). The results are shown in Table 1.

Examples 5-7
A photoelectric conversion device was prepared and evaluated in the same manner as in Example 1 except that the molar ratio of basic compound A to ionic compound B in Example 1 was changed as shown in Table 1. The results are shown in Table 1.

Example 8
The hole transport material in Example 6 is an organic hole transport material represented by the following structural formula (6) (2,2 ′, 7,7′-tetrakis (N, N-di-p-methoxyphenylamino) -9,9 ′ A photoelectric conversion element was produced and evaluated in the same manner as in Example 6 except that the change was made to -spirobifluorene: Spiro-OMeTAD, Merck Ltd.). The results are shown in Table 1.

Example 9
A photoelectric conversion element was produced in the same manner as in Example 6 except that the hole transport material in Example 6 was changed to an organic hole transport material (LT-S9170: HTM1, Luminescence Technology) represented by the following structural formula (7). ,evaluated. The results are shown in Table 1.

Comparative Example 1
A photoelectric conversion device was prepared and evaluated in the same manner as in Example 8 except that the basic compound A in Example 8 was changed to 4-tert-butylpyridine (TBP, Tokyo Chemical Industry Co., Ltd.). The results are shown in Table 1.

Comparative Example 2
A photoelectric conversion device was prepared and evaluated in the same manner as in Example 8 except that the ionic compound B in Example 8 was changed to lithium bis (trifluoromethanesulfonyl) imide (LiTFSI, Kishida Chemical Co., Ltd.). The results are shown in Table 1.

Comparative Example 3
The basic compound A in Example 8 was changed to 4-tert-butylpyridine (TBP, Tokyo Chemical Industry Co., Ltd.), and the ionic compound B was changed to lithium bis (trifluoromethanesulfonyl) imide (LiTFSI, Kishida Chemical Co., Ltd.). Except for this, a photoelectric conversion element was prepared and evaluated in the same manner as in Example 8. The results are shown in Table 1.

From the results in Table 1, it can be seen that the photoelectric conversion elements of Examples 1 to 9 are suppressed in voltage drop even in a high temperature environment, and the chargeability to the secondary battery is maintained. Therefore, it can be used without changing the setting of the PMIC. This is presumably because the crystallization of the hole transport layer is suppressed and the contact interface between the electron transport layer and the hole transport layer is also kept good.
On the other hand, since the basic compounds A and / or ionic compounds B used in Comparative Examples 1 to 3 were outside the scope of the present invention, desired characteristics could not be obtained.
As can be seen from the above, the photoelectric conversion element of the present invention suppresses the voltage drop even in a high temperature environment, and can charge the secondary battery regardless of the temperature environment.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 1st electrode 3 Hole blocking layer 4 Electron transport layer 5 Photosensitizing compound 6 Hole transport layer 7 Second electrode 8, 9 Lead line 11 Photoelectric conversion element 12 PMIC
13 Sensor / Communication Circuit 14 Secondary Battery

ACS Appl. Mater. Interfaces, 2015, 7 (21), pp 111107-11116

Claims (6)

A substrate, a first electrode, a hole blocking layer, an electron transport layer, a photosensitizing compound adsorbed on the surface of the electron transport layer, a hole transport layer, and a second electrode; The transport layer includes a basic compound A represented by the following general formula (1) and an ionic compound B represented by the following general formula (2).

(Wherein R ₁ and R ₂ each independently represents an alkyl group or an aromatic hydrocarbon group and represent the same or different groups, or R ₁ and R ₂ are bonded to each other and contain a nitrogen atom) Represents a heterocyclic group.)

(In the formula, X ⁺ represents a counter cation.)   The photoelectric conversion element according to claim 2, wherein the ionic compound B is lithium bis (fluoromethanesulfonyl) imide. 3. The photoelectric conversion device according to claim ₁ , wherein R ₁ and R _{2 in} the general formula (1) are bonded to each other and are a heterocyclic group containing a nitrogen atom.   4. The photoelectric device according to claim 1, wherein the molar ratio of the basic compound A to the ionic compound B is A: B = 1: 0.1 to 1: 0.5. Conversion element. The said hole transport layer contains the organic hole transport material represented by following General formula (3), The photoelectric conversion element of any one of Claims 1-4 characterized by the above-mentioned.

(In the formula, R ₃ represents a hydrogen atom or a methyl group.)   A solar cell comprising the photoelectric conversion element according to any one of claims 1 to 5.

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