JP2016178102A - Photoelectric conversion element and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element capable of obtaining good photoelectric conversion properties even in the case of extremely faint light (from 10 Lux to 50 Lux) such as indoor light.SOLUTION: A photoelectric conversion element includes an electrode, a hole blocking layer, an electron transport layer, a hole transport layer and an electrode, in the order. The hole transport layer contains at least one basic compound represented by the following general formula (1). (In the formula, Rrepresents a straight or branched chain alkyl group, phenyl group, tolyl group or benzyl group.)SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photoelectric conversion element and a secondary battery.

  In recent years, the driving power in electronic circuits has become very small, and various electronic components such as sensors can be driven even with weak power (μW order). Furthermore, when using sensors, it is expected to be applied to a self-supporting power source (environmental power generation element) that can generate and consume on the spot. Among them, solar cells (a type of photoelectric conversion element) are elements that can generate power anywhere if there is light. Has attracted attention as. A small-sized energy harvesting element can be arranged in various places, and can be combined with a secondary battery to be a primary battery that does not require replacement. The power generation performance can be improved by further reducing the size and increasing the number of times sensor information is transmitted by wireless communication.

Among solar cells, dye-sensitized solar cells announced by Graetzel et al. Of Lausanne University of Technology have been reported to have higher photoelectric conversion characteristics than amorphous silicon solar cells in a weak indoor light environment (non- Patent Document 1).
Usually, the illuminance of indoor light such as an LED light or a fluorescent lamp is about 200 Lux to 1000 Lux, which is very weak light compared to direct sunlight (approximately 100000 Lux). The location where the energy harvesting element is installed is often set on a wall or the like, not directly under room light. In that case, the light irradiated to the energy harvesting element further becomes weak light. The walls of hallways and the like are about 10 Lux to 50 Lux, and high conversion efficiency is desired even in an ultra low light environment.

  This solar cell has a structure in which a porous metal oxide semiconductor is provided on a transparent conductive glass substrate, a dye adsorbed on the surface thereof, an electrolyte having a redox pair, and a counter electrode. Graetzel et al. Significantly improved the photoelectric conversion efficiency by making a metal oxide semiconductor electrode such as titanium oxide porous to increase the surface area and adsorbing a ruthenium complex as a dye on a single molecule basis (for example, Patent Documents). 1, Non-Patent Documents 2 and 3).

A dye-sensitized solar cell using a conventional electrolytic solution with high power generation performance has concerns about volatilization or leakage of the electrolytic solution. Therefore, when practical use is assumed, solidification of the electrolytic solution is desired. Conventionally, the following solid-state dye-sensitized solar cells with high power generation performance have been reported.
1) Using an inorganic semiconductor (for example, see Non-Patent Document 4)
2) A material using a low molecular weight organic hole transport material (for example, see Patent Document 2, Non-Patent Documents 5 and 6)
3) Using conductive polymer (for example, see Patent Document 3 and Non-Patent Document 7)

  As described above, all of the solid-state photoelectric conversion elements that have been studied so far have been reported only for power generation performance in simulated sunlight, and no power generation performance for indoor light has been reported. In particular, no power generation performance has been reported in an ultra-fine light environment (10 Lux to 50 Lux).

  In view of the above problems, an object of the present invention is to provide a photoelectric conversion element that can obtain good photoelectric conversion properties even in the case of ultra-weak irradiation light (10 Lux to 50 Lux) such as room light. .

In order to solve the above problems, the photoelectric conversion element of the present invention is a photoelectric conversion element having an electrode, a hole blocking layer, an electron transport layer, a hole transport layer, and an electrode in this order. It contains at least one basic compound represented by the formula (1).
(In the formula, R ₁ represents a linear or branched alkyl group, a phenyl group, a tolyl group, or a benzyl group.)

  ADVANTAGE OF THE INVENTION According to this invention, even if it is the case of ultra weak irradiation lights (10 Lux to 50 Lux), such as room light, the photoelectric conversion element which can obtain favorable photoelectric conversion property can be provided.

It is the schematic of an example showing the structure of the photoelectric conversion element which concerns on this invention.

Hereinafter, the photoelectric conversion element 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.
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, and specifically includes a solar cell or a photodiode.

The structure of the photoelectric conversion element will be described with reference to FIG. FIG. 1 is an example of a cross-sectional view of a photoelectric conversion element and a solar cell.
The photoelectric conversion element of the present invention has two electrodes and a hole blocking layer, an electron transport layer, and a hole transport layer in this order between the two electrodes.
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 material 5 is adsorbed on the electron transporting material in 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. ing. FIG. 1 shows an example of a configuration in which 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.
Of the two electrodes, the electrode on the substrate side will be described as the first electrode, and the electrode facing the first electrode will be described as the second electrode.

<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 for the first electrode include indium tin oxide (hereinafter referred to as ITO), fluorine-doped tin oxide (hereinafter referred to as FTO), antimony-doped tin oxide (hereinafter referred to as ATO), indium / tin oxide, and the like. Examples thereof include zinc oxide, niobium / titanium oxide, and graphene, and these may be used alone or in a plurality of layers.
The thickness of the first electrode is preferably 5 nm to 10 μm, more preferably 50 nm to 1 μm.

  The first electrode is preferably provided on the substrate 1 made of a material transparent to visible light in order to maintain a certain hardness. Examples of the substrate include glass, a transparent plastic plate, a transparent plastic film, and an inorganic transparent material. A 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 plastic film can be used. Etc.

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>
The hole blocking layer 3 used in the present invention is not particularly limited as long as it is transparent to visible light and is an electron transporting material, but titanium oxide is particularly preferable. Further, it is provided in order to suppress a decrease in power 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. The effect of the hole blocking layer 3 is particularly remarkable in the solid dye-sensitized solar cell. Compared with a wet dye-sensitized solar cell using an electrolyte solution, a solid dye-sensitized solar cell using an organic hole transport material or the like recombines holes in the hole transport material and electrons on the electrode surface ( This is due to the high speed of reverse electron transfer.

  The method for forming the hole blocking layer is not limited, but high internal resistance is required to suppress the loss current in room light, and the film forming method is also important. 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, and the film density is sufficiently high and loss current can be suppressed.

  This hole blocking layer is also formed for the purpose of preventing electronic contact between the first electrode 2 and the hole transport layer 6. The thickness of the hole blocking layer is not particularly limited, but is preferably 5 nm to 1 μm, more preferably 500 to 700 nm for wet film formation, and more preferably 10 nm to 30 nm for dry film formation.

<Electron transport layer>
The photoelectric conversion element of the present invention forms the porous electron transport layer 4 on the hole blocking layer 3 and may be a single layer or a multilayer.
In the case of multiple layers, a dispersion of semiconductor fine particles having different particle diameters can be applied in multiple layers, or different types of semiconductors, and application layers having different compositions of resins and additives can be applied in multiple layers.
Multi-layer coating is an effective means when the film thickness is insufficient with a single coating.
In general, as the thickness of the electron transport layer increases, the amount of supported photosensitizing material per unit projected area also increases, so that the light capture rate increases. Loss due to coupling also increases.
Therefore, the film thickness of the electron transport layer is preferably 100 nm to 100 μm.

The semiconductor is not particularly limited, and a known semiconductor can be used.
Specifically, a single semiconductor such as silicon or germanium, a compound semiconductor typified by a metal chalcogenide, a compound having a perovskite structure, or the like can be given.
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, an oxide semiconductor is preferable, and titanium oxide, zinc oxide, tin oxide, and niobium oxide are particularly preferable, and they 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.

Although there is no restriction | limiting in particular in the size of a semiconductor fine particle, 1-100 nm is preferable and, as for the average particle diameter of a primary particle, 5-50 nm is more preferable.
Further, the efficiency can be improved by the effect of scattering incident light by mixing or laminating semiconductor fine particles having a larger average particle diameter. In this case, the average particle size of the semiconductor is preferably 50 to 500 nm.

There is no restriction | limiting in particular in the preparation methods of an electron carrying layer, The method of forming a thin film in vacuum, such as sputtering, and the wet film forming method are mentioned.
In view of the manufacturing cost and the like, a wet film forming method is particularly preferable, and a method in which a paste in which semiconductor fine particle powder or sol is dispersed is prepared and applied onto an electron collecting electrode substrate 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.

When a dispersion of semiconductor fine particles is prepared by mechanical pulverization or using a mill, it is formed by dispersing at least semiconductor fine particles alone or a mixture of semiconductor fine particles and a resin in water or an organic solvent.
Examples of the resin used at this time include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid esters, and methacrylic acid esters, silicon resins, phenoxy resins, polysulfone resins, polyvinyl butyral resins, and polyvinyl resins. Formal resins, polyester resins, cellulose ester resins, cellulose ether resins, urethane resins, phenol resins, epoxy resins, polycarbonate resins, polyarylate resins, polyamide resins, polyimide resins and the like can be mentioned.

  Examples of the solvent for dispersing the semiconductor fine particles 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, or Ester solvents such as n-butyl acetate, ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, or N-methyl-2-pyrrolidone Amide solvents such as 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 can be used alone or as a mixed solvent of two or more.

  In order to prevent re-aggregation of particles, a paste of semiconductor fine particles obtained by a dispersion of semiconductor fine particles or a sol-gel method is used, such as acids such as hydrochloric acid, nitric acid, acetic acid, polyoxyethylene (10) octylphenyl ether, etc. Surfactants, chelating agents such as acetylacetone, 2-aminoethanol, and ethylenediamine can 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 added at this time include polymers such as polyethylene glycol and polyvinyl alcohol, and thickeners such as ethyl cellulose.

  The semiconductor fine particles are preferably 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. . These processes may be performed alone or in combination of two or more.

  In the case of firing, the range of the firing temperature is not particularly limited, but if the temperature is raised too much, the resistance of the substrate may increase or the substrate may melt, so 30 to 700 ° C is preferable, and 100 to 600 ° C is more. preferable. Moreover, although there is no restriction | limiting in particular also in baking time, 10 minutes-10 hours are preferable.

The microwave irradiation may be performed from the electron transport layer forming side or from the back side.
Although there is no restriction | limiting in particular in irradiation time, It is preferable to carry out within 1 hour.

  For example, chemical plating or titanium trichloride using a titanium tetrachloride aqueous solution or a mixed solution with an organic solvent for the purpose of increasing the surface area of the semiconductor fine particles and increasing the electron injection efficiency from the photosensitizing material to the semiconductor fine particles after firing. Electrochemical plating using an aqueous solution may be performed.

A film in which semiconductor fine particles having a diameter of several tens of nanometers 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 body relative to the area of the semiconductor fine particles applied to the substrate. Accordingly, the roughness factor is preferably as large as possible, but is also related to the film thickness of the electron transport layer, and is preferably 20 or more in the present invention.

<Photosensitizing material>
In the present invention, in order to further improve the conversion efficiency, the photosensitizing material is adsorbed on the surface of the electron transporting semiconductor that is the electron transporting layer 4.
The photosensitizing material 5 is not limited to the above as long as it is a compound that is photoexcited by the excitation light used, and specific examples thereof include the following compounds.
The metal complex compounds described in JP 7-500630 A, JP 10-233238 A, JP 2000-26487 A, JP 2000-323191 A, JP 2001-59062 A, etc. 10-93118, JP-A No. 2002-164089, JP-A No. 2004-95450, J. Phys. Chem. C, 7224, Vol. 111 (2007), and the like. No. 95450, Chem. Commun., 4887 (2007), etc., JP 2003-264010 A, JP 2004-63274 A, JP 2004-115636 A, JP 2004-200068 A. Publication, JP 2004-235052 A, J. Am. Chem. Soc., 12218, Vol. 126 (2004), Chem. Commun., 3036 (2003), Angew. Chem. Int. Ed., 1923, Vol. .47 (2008) etc. Compounds, thiophene compounds described in J. Am. Chem. Soc., 16701, Vol. 128 (2006), J. Am. Chem. Soc., 14256, Vol. 128 (2006), etc., JP-A-11-86916 Cyanine dyes described in JP-A-11-214730, JP-A-2000-106224, JP-A-2001-76773, JP-A-2003-7359, etc., JP-A-11-214731, Merocyanine dyes described in Kaihei 11-238905, JP-A-2001-52766, JP-A-2001-76775, JP-A-2003-7360, etc., JP-A-10-92477, JP-A-11-273754 9-arylxanthene compounds, JP-A-10-93118, JP-A-2003-31 described in JP-A-11-273755, JP-A-2003-31273, and the like. 273, etc., JP-A-9-199744, JP-A-10-233238, JP-A-11-204821, JP-A-11-265738, J. Phys. Chem. , 2342, Vol. 91 (1987), J. Phys. Chem. B, 6272, Vol. 97 (1993), Electroanal. Chem., 31, Vol. 537 (2002), JP 2006-032260, J Porphyrins Phthalocyanines, 230, Vol. 3 (1999), Angew. Chem. Int. Ed., 373, Vol. 46 (2007), Langmuir, 5436, Vol. 24 (2008), etc. Etc. Among these, it is particularly preferable to use metal complex compounds, coumarin compounds, polyene compounds, indoline compounds, and thiophene compounds.

More preferably, D131 represented by the following structural formula (4) manufactured by Mitsubishi Paper Industries, D102 represented by the following structural formula (5), and D358 represented by the following structural formula (6) are exemplified.

As a method for adsorbing the photoimageable material 5 to the electron transport layer 4, a method of immersing an electron current collecting electrode containing semiconductor fine particles in a photosensitizing material solution or dispersion, a solution or dispersion is used as an electron transport layer. It is possible to use a method of applying to and adsorbing to the surface.
In the former case, an immersion method, a dip method, a roller method, an air knife method, or the like can be used.
In the latter case, a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, a spray method, or the like can be used.
Further, it may be adsorbed in a supercritical fluid using carbon dioxide or the like.

When adsorbing the photosensitizing material, a condensing agent may be used in combination.
The condensing agent has a catalytic action that seems to physically or chemically bind the photosensitizing material and the electron transport compound to the inorganic surface, or acts stoichiometrically to advantageously shift the chemical equilibrium. Any of them 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 material include alcohol solvents such as water, methanol, ethanol, and isopropyl alcohol,
Ketone solvents 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 diethyl 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 can be mentioned, and these can be used alone or as a mixture of two or more.

Further, depending on the type of photosensitizing material, there are materials 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 preferably a steroid compound such as cholic acid or chenodeoxycholic acid, a long-chain alkyl carboxylic acid or a long-chain alkyl phosphonic acid, and is appropriately selected according to the dye used.
The addition amount of these aggregating and dissociating agents is preferably 0.01 to 500 parts by mass, more preferably 0.1 to 100 parts by mass with respect to 1 part by mass of the dye.
The temperature at the time of adsorbing the photosensitizing material or the photosensitizing material and the aggregation / dissociation agent using these is preferably from −50 ° C. to 200 ° C.

Moreover, this adsorption may be carried out while standing or stirring.
Examples of the stirring method include, but are not limited to, a stirrer, a ball mill, a paint conditioner, a sand mill, an attritor, a disperser, and ultrasonic dispersion.
The time required for adsorption is preferably 5 seconds or more and 1000 hours or less, more preferably 10 seconds or more and 500 hours or less, and further preferably 1 minute or more and 150 hours.
Adsorption is preferably performed in a dark place.

<Hole transport layer>
Generally, as a hole transport layer, an electrolyte solution in which a redox couple is dissolved in an organic solvent, a gel electrolyte in which a liquid in which the redox couple is dissolved in an organic solvent is impregnated in a polymer matrix, a molten salt containing the redox couple, a solid An electrolyte, an inorganic hole transport material, an organic hole transport material, or the like is used. It is important that the hole transport layer 6 in the present invention contains at least one basic compound represented by the structural formula (1). Further, it is preferable to further contain an organic hole transport material.

The hole transport layer in the present invention may be a single layer structure or a laminated structure composed of different compounds. In the case of a laminated structure, it is preferable to use a polymer material as the hole transport material of the hole transport layer close to the second electrode 7.
This is because the surface of the porous electron transport layer can be further smoothed and the photoelectric conversion characteristics can be improved by using a polymer material having excellent film forming properties.
In addition, since it is difficult for the polymer material to 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 in the single layer structure, a known organic hole transport compound is used.
Specific examples thereof include oxadiazole compounds disclosed in JP-B No. 34-5466, triphenylmethane compounds disclosed in JP-B No. 45-555, JP-B No. 52-4188, and the like. Pyrazoline compounds shown, hydrazone compounds shown in JP-B-55-42380, oxadiazole compounds shown in JP-A-56-123544, etc., JP-A-54-58445 And the stilbene compounds disclosed in JP-A-58-65440 and JP-A-60-98437.

  Among them, the following structural formulas described in J. Am. Chem. Soc., 133 (2011) 18042 (non-patent document 5) and J. Am. Chem. Soc., 135 (2013) 7378 (non-patent document 6) The organic hole transport material (2,2 ′, 7,7′-tetrakis (N, N-di-p-methoxyphenylamino) -9,9′-spirobifluorene: spiro-OMeTAD) represented by (3) is particularly excellent. The photoelectric conversion characteristics are shown. In spiro-OMeTAD, in addition to high hole mobility, two benzidine skeleton molecules are twisted and bonded. Therefore, a nearly spherical electron cloud is formed, and excellent photoelectric conversion characteristics are exhibited due to good hopping transmission between molecules. In addition, it is highly soluble, soluble in various organic solvents, and is amorphous (amorphous material having no crystal structure), so it is easy to be densely packed in the porous electron transport layer, which is useful for solid dye-sensitized solar cells. Has useful properties. Furthermore, since it does not have a light absorption characteristic of 450 nm or more, the photosensitizing material can efficiently absorb light, and has characteristics useful for a solid dye-sensitized solar cell. The film thickness of the hole transport layer made of spiro-OMeTAD is not limited, but preferably has a structure that enters the pores of the porous electron transport layer, preferably 0.01 μm or more on the electron transport layer. About 1 to 10 μm is more preferable.

As the polymer material used for the hole transport layer close to the second electrode 7 used in the laminated structure, a known hole transport polymer material is used.
Specific examples thereof include 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-bithiophene) Polythiophene compounds such as
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).

  Of these, polythiophene compounds and polyarylamine compounds are particularly preferred in consideration of carrier mobility and ionization potential.

Moreover, you may add various additives to the organic hole transport material shown above.
Additives 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 of the lithium compound include lithium trifluoromethanesulfonylimide and lithium diisopropylimide.
It preferably contains an ionic liquid imidazolium compound.

In the photoelectric conversion element of the present invention, the hole transport layer contains at least one basic compound represented by the following general formula (1), whereby the internal resistance of the photoelectric conversion element is further increased, and ultra-weak light such as room light is generated. Loss current at (10 Lux to 50 Lux) can be reduced. In addition, the basic compound represented by the general formula (1) is an amine derivative having a dibenzyl skeleton, and has a higher oxidation potential than the hole transport material represented by the structural formula (3) and inhibits hole transport. There is no. An amine derivative having a dialkyl skeleton has a low oxidation potential and inhibits hole transport. Therefore, it was found that an amine derivative having a dibenzyl skeleton has a high basicity and an oxidation potential that does not inhibit hole transport, so that an appropriate internal resistance can be obtained by adding it to the hole transport layer.
(In the formula, R ₁ represents a linear or branched alkyl group, a phenyl group, a tolyl group, or a benzyl group.)

The linear or branched alkyl group for R ₁ is preferably a linear or branched alkyl group having 1 to 4 carbon atoms. For example, a methyl group, an ethyl group, a propyl group, a butyl group, a tertiary butyl group and the like are preferable.

Specific examples of the compound represented by the general formula (1) are shown below, but are not limited thereto.

  The addition amount of the basic compound 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. It is more preferable that the amount is not less than 15 parts by mass.

In the present invention, in addition to at least one basic compound represented by the general formula (1), the hole transport layer further includes at least one basic compound represented by the following general formula (2). By adding, a particularly high open circuit voltage can be obtained.
Further, the internal resistance of the photoelectric conversion element is increased, and the loss current in weak light such as room light can be reduced. Therefore, an open circuit voltage higher than that of a conventional basic compound can be obtained.
(Wherein R ₂ and R ₃ represent a substituted or unsubstituted alkyl group or an aromatic hydrocarbon group, which may be the same or different. R ₂ and R ₃ are bonded to each other and contain a nitrogen atom. (A substituted or unsubstituted heterocyclic group may be formed.)
As the substituted or unsubstituted alkyl group or aromatic hydrocarbon group for R ₂ and R ₃ , a methyl group, an ethyl group, a propyl group, a butyl group, a tertiary butyl group, a tolyl group, a biphenyl group and the like are preferable.

  Conventionally, the following compound No. which is a compound represented by the general formula (2) is used. The compound itself classified into the basic compound represented by 2-1 is known. Some of these compounds are known to be used as basic compounds in iodine electrolyte dye-sensitized solar cells. However, it is reported that although the open circuit voltage is high, the short circuit current density is greatly reduced, and the photoelectric conversion characteristics are significantly deteriorated.

  The hole transport layer of the present invention preferably uses an organic hole transport material, which is different from the hole transport model by the iodine electrolyte solution or the like. Therefore, the amount of decrease in the short-circuit current density is small, and a high open circuit voltage can be obtained, whereby excellent photoelectric conversion characteristics can be obtained. Furthermore, when photoelectric conversion was performed in weak light such as room light, which is rarely reported, it was verified that a particularly significant advantage appears.

Specific examples of the compound represented by the general formula (2) are shown below, but are not limited thereto. The Nikkaji number is shown next to the structural formula.

  The addition amount of the basic compound represented by the general formula (2) 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. It is more preferable that the amount is not less than 15 parts by mass.

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.

  As the hole transport layer, a hole transport layer is formed directly on the electron transport layer 4 carrying the photoimageable material. There is no restriction | limiting in particular in the preparation methods of a hole transport layer, 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 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. The fluid is not particularly limited as long as it is in the above state, and can be appropriately selected according to the purpose. However, a fluid having a low critical temperature is preferable.
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 the present invention, after the hole transport layer is provided on the first electrode provided with the electron transport layer coated with the photoimageable material, a press treatment step may be performed.
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 or more, more preferably 30 kgf / cm ² or more. Although there is no restriction | limiting in particular in the time to press-process, 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 and the second electrode before the counter electrode is provided after the pressing process. 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 is not particularly limited, and examples thereof include a method for forming a thin film in a vacuum such as sputtering and vacuum deposition, and a wet film formation method.
In the wet film forming method, it is preferable to prepare a paste in which a metal oxide powder or sol is dispersed and apply the paste onto the hole transport layer.

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 is newly applied after the hole transport layer is formed or on the metal oxide.
The second electrode can be usually the same as the first electrode described above, and the support is not necessarily required in a configuration in which the strength and sealability are sufficiently maintained.
Specific examples of the second electrode material 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.
The film thickness of the second electrode layer is not particularly limited, and may be used alone or in combination of two or more.
The coating of the second electrode can be appropriately formed on the hole transport layer by a method such as coating, laminating, vapor deposition, CVD, or bonding depending on the type of material used and the type of hole transport layer.

In order to operate as a dye-sensitized solar cell, at least one of the first electrode and the second electrode must be substantially transparent.
In the dye-sensitized solar cell of the present invention, a method in which the first electrode side is transparent and sunlight is incident from the first electrode side is preferable. In this case, it is preferable to use a material that reflects light on the second electrode side, and glass, plastic, or metal thin film on which metal, conductive oxide is deposited is preferable.
It is also effective to provide an antireflection layer on the sunlight incident side.

<Application>
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. Moreover, it can apply also to an electrical storage apparatus by charging to a secondary battery. Examples of devices using such a 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.

<Synthesis Example of Basic Compound Represented by General Formula (1)>
It can be synthesized by a general Ullman reaction.
(In the formula, R ₁ represents a linear or branched alkyl group, a phenyl group, a tolyl group, or a benzyl group. X represents a halogen.)

<Synthesis Example of Basic Compound Represented by General Formula (2)>
Similarly to the reported example (J. Org. Chem., 67 (2002) 3029), it can be easily synthesized from the following route.
(Wherein R ₂ and R ₃ represent a substituted or unsubstituted alkyl group or an aromatic hydrocarbon group, which may be the same or different. R ₂ and R ₃ are bonded to each other and contain a nitrogen atom. A substituted or unsubstituted heterocyclic group may be formed, and X represents a halogen element.)

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

[Example 1]
(Production of titanium oxide semiconductor electrode)
A dense hole blocking layer of titanium oxide was formed on the ITO-coated glass substrate by reactive sputtering with oxygen gas using a target made of metallic titanium.
Next, 3 g of titanium oxide (P90 manufactured by Nippon Aerosil Co., Ltd.), 0.2 g of acetylacetone, and 0.3 g of surfactant (polyoxyethylene octylphenyl ether manufactured by Wako Pure Chemical Industries, Ltd.) were mixed with 5.5 g of water and 1.0 g of ethanol in a bead mill. The treatment was applied for 12 hours.
1.2 g of polyethylene glycol (# 20,000) was added to the obtained dispersion to prepare a paste.
This paste was applied on the hole blocking layer so as to have a film thickness of 1.5 μm, dried at room temperature, and then baked in air at 500 ° C. for 30 minutes to form a porous electron transport layer.

(Preparation of dye-sensitized solar cell)
The titanium oxide semiconductor electrode is immersed in D358 (0.5 mM, acetonitrile / t-butanol (volume ratio 1: 1) solution) manufactured by Mitsubishi Paper Industries, Ltd. represented by the structural formula (6) as a sensitizing dye. The photosensitized material was adsorbed by allowing it to stand in the dark for a long time.
Organic hole transport material represented by the following structural formula (7) (Made by Luminescence Technology, Brand: N, N, N ', N'-Tetrakis (4-methoxyphenyl) benzidine, Product Number: LT-N212) (Solid content 14 Mass%), lithium bis (trifluoromethanesulfonyl) imide (solid content 1 mass%) manufactured by Kanto Chemical Co., Inc., and basic compound No. 1 represented by the general formula (1). A solution obtained by adding 1-1 (solid content: 1.4% by mass) to chlorobenzene was applied onto a semiconductor electrode carrying a photosensitizing material by spin coating to form a hole transport layer. On this, silver was vacuum-deposited with 100 nm to produce a second electrode, and a solar cell was produced.

(Evaluation of dye-sensitized solar cell)
The resulting white LED illumination of a dye-sensitized solar cell (500 lux: 125μW / cm ^2, 50 lux: 12.5μW / cm ^2, 10 lux: 2.5μW / cm ²⁾ for measurement of a photoelectric conversion efficiency of. The white LED was measured with a desk lamp CDS-90α (study mode) manufactured by Cosmo Techno, and the evaluation device was measured with a solar cell evaluation system As-510-PV03 manufactured by NF Circuit Design Block.
Moreover, the open circuit voltage, the short circuit current density, and the shape factor were measured based on JIS C8913.
The results are shown in Table 2.

[Examples 2 to 6]
A solar cell was prepared and evaluated in the same manner as in Example 1 except that the basic compound represented by the general formula (1) in Example 1 was changed as shown in Table 1. The results are shown in Table 2.

[Example 7]
The organic hole transport material in Example 1 is represented by the above structural formula (3) (Merck Co., Ltd., brand: 2,2 ', 7,7'-tetrakis (N, N-di-p A solar cell was prepared and evaluated in the same manner as in Example 1 except that -methoxyphenylamino) -9,9'-spirobifluorene, product number: SHT-263) was changed. The results are shown in Table 2.

[Examples 8 to 17]
The organic hole transport material in Example 1 is represented by the above structural formula (3) (Merck Co., Ltd., brand: 2,2 ', 7,7'-tetrakis (N, N-di-p -methoxyphenylamino) -9,9'-spirobifluorene, product number: SHT-263), the basic compound represented by the general formula (1) was changed as shown in Table 1. Further, a solar cell was produced in the same manner as in Example 1 except that the exemplified basic compound (solid content: 1.4% by mass) represented by the general formula (2) was added as shown in Table 1. evaluated. The results are shown in Table 2.

[Examples 18 to 19]
A solar cell was produced and evaluated in the same manner as in Example 8 except that the pigment in Example 8 was changed as shown in Table 1. The results are shown in Table 2.

[Example 20]
A solar cell was obtained in the same manner as in Example 1 except that lithium bis (trifluoromethanesulfonyl) imide in Example 7 was changed to 1-n-hexyl-3-methylimidazolinium bis (trifluoromethylsulfonyl) imide. Prepared and evaluated. The results are shown in Table 2.

[Comparative Example 1]
Exemplified basic compound No. 1 represented by the general formula (1) in Example 1 was used. A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that 1-1 was changed to the following structural formula (8). The results are shown in Table 2.

[Comparative Example 2]
Exemplified basic compound No. 1 represented by the general formula (1) in Example 1 was used. A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that 1-1 was changed to the following structural formula (9). The results are shown in Table 2.

[Comparative Example 3]
Exemplified basic compound No. 1 represented by the general formula (1) in Example 1 was used. 1-1 is exemplified basic compound No. 1 represented by the general formula (2). A solar cell was produced and evaluated in the same manner as in Example 1 except that it was changed to 2-3. The results are shown in Table 2.

The photoelectric conversion elements of Comparative Example 1 using a dimethylamino compound having a low oxidation potential and Comparative Example 2 using a methylphenyl compound having a weak basicity have poor conversion efficiency, and the characteristics in an ultra-low light environment are even worse. . In particular, the decrease in open circuit voltage and form factor is significant.
However, the photoelectric conversion elements of Examples 1 to 20 are all excellent in conversion efficiency and very excellent in an ultra-low light environment. By adding the basic compound represented by the general formula (1), the internal resistance was controlled, and excellent power generation performance could be obtained even under ultra-weak light. In addition, Examples 7 to 20 using the hole transport material represented by the structural formula (3) are particularly excellent in conversion efficiency. Furthermore, Examples 8 to 20 in which the basic compound represented by the general formula (2) is mixed have a high open-circuit voltage and excellent conversion efficiency.

Although the photoelectric conversion element of Comparative Example 3 using only the basic compound represented by the general formula (2) has excellent conversion efficiency under 500 Lux, the conversion efficiency under ultra-low light environment is inferior.
As is apparent from the above, it can be seen that the photoelectric conversion element of the present invention exhibits excellent photoelectric conversion characteristics in an excellent ultra-low light environment.

<Example 21>
Using the photoelectric conversion element created in Example 1, a secondary battery (semiconductor battery) for charging the generated power was produced.
On the glass substrate, ITO was formed to a thickness of 200 nm by sputtering. A solution obtained by dissolving tin 2-ethylhexanoate (0.24 g) and silicon oil (TSF433, 1.2 g) in toluene (1.28 mL) was applied by spin coating. Baked for 1 hour. The obtained film was irradiated with ultraviolet rays having a wavelength of 254 nm at an intensity of 40 mW / cm ² for 5 hours. Next, nickel oxide was formed at 150 nm and ITO was formed at 200 nm by sputtering to produce a semiconductor battery. Finally, three photoelectric conversion elements prepared in Example 1 were prepared, and after three cells were connected in series, the second electrode of the photoelectric conversion element and the first electrode of the semiconductor battery obtained above were connected with an alligator clip. The first electrode of the photoelectric conversion element and the second electrode of the semiconductor battery were connected by an alligator clip. The performance of the photoelectric conversion element / semiconductor cell composite element produced in this manner was evaluated as follows.
Pseudo sunlight was irradiated from the 1st electrode side of the photoelectric conversion element on the conditions made into the open circuit. As a result of measuring the photoelectromotive force of the electrode during this irradiation, it was confirmed that the photoelectrode (first electrode) produced a negative electromotive force with respect to the counter electrode by the light irradiation. That is, by this light irradiation, the electrode active material constituting the photoelectrode was reduced and the battery was charged. Light irradiation was continued and it was confirmed that the voltage of the photoelectrode was saturated, and then the light irradiation was stopped and the charging was terminated.
When the charged battery was placed in the dark, the external circuit was closed and the output voltage was measured with a potentiostat, it was 2.4V. When discharge was performed at a constant current density of 15 μA / cm ^{2 using} the photoelectrode as the negative electrode and the counter electrode as the positive electrode, the discharge capacity was 0.875 μAh / cm ² .

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 1st electrode 3 Hole blocking layer 4 Electron transport layer 5 Photosensitizing material 6 Hole transport layer 7 2nd electrode 8, 9 Lead line

Japanese Patent No. 2664194 Japanese Patent Laid-Open No. 11-144773 JP 2000-106223 A

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Claims (8)

A photoelectric conversion element having an electrode, a hole blocking layer, an electron transport layer, a hole transport layer, and an electrode in this order, wherein the hole transport layer contains at least one basic compound represented by the following general formula (1) The photoelectric conversion element characterized by the above-mentioned.
(In the formula, R ₁ represents a linear or branched alkyl group, a phenyl group, a tolyl group, or a benzyl group.) The photoelectric conversion element according to claim 1, wherein the hole transport layer further contains at least one basic compound represented by the following general formula (2).
(Wherein R ₂ and R ₃ represent a substituted or unsubstituted alkyl group or an aromatic hydrocarbon group, which may be the same or different. R ₂ and R ₃ are bonded to each other and contain a nitrogen atom. (A substituted or unsubstituted heterocyclic group may be formed.) The photoelectric conversion element according to claim 1 or 2, wherein the hole transport layer contains a hole transport material represented by the following structural formula (3).
  The said electron carrying layer contains at least 1 selected from the group of a titanium oxide, a zinc oxide, a tin oxide, and niobium oxide as an electron transport material, It is any one of Claim 1 thru | or 3 characterized by the above-mentioned. Photoelectric conversion element.   The photoelectric conversion element according to claim 1, wherein the hole blocking layer contains titanium oxide.   6. The photoelectric conversion element according to claim 5, wherein the hole blocking layer is formed by sputtering.   The photoelectric conversion element according to claim 1, wherein the hole transport layer includes an ionic liquid imidazolium compound.   A secondary battery comprising the photoelectric conversion element according to claim 1.