JP2015141944A - Photoelectric conversion element and solar cell including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element capable of exhibiting a high short circuit current density.SOLUTION: A photoelectric conversion element of the present invention includes a substrate, a first electrode, an electron transport layer, a photoelectric conversion layer containing a pigment and a pigment supporting body, a hole transport layer and a second electrode. The pigment includes a compound represented by the following formula (1). (where, R-Reach independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group having 1-6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3-6 carbon atoms, a polyethylene oxide group having a carbon number of 2-6, or a substituted or unsubstituted aromatic ring-containing group having 4-10 carbon atoms, while R-Rdo not represent a hydrogen atom at the same time; X-Xeach independently represent a halogen atom; and M represents an atom belonging to the 14 group in the periodic table or a transition metal.) The pigment supporting body includes an organic compound having an oxygen atom, a nitrogen atom or a sulfur atom and having a weight average molecular weight (Mw) of 500 or more.

Description

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

  In recent years, photovoltaic power generation technology that uses solar energy, which is one of renewable energies, without using fossil fuels has attracted attention as a means of solving the global warming problem. Among these solar power generation technologies, dye-sensitized solar cells generate electricity by the same mechanism as the photo-induced electron transfer performed by chlorophyll dyes, so they are the next generation of low-cost, high-performance roof-top solar cells. As one of the highlights.

  The general structure of such a dye-sensitized solar cell includes a substrate, a first electrode, an electron transport layer, a semiconductor layer (photoelectric conversion layer) carrying a sensitizing dye, a hole transport layer, and a second electrode. Are sequentially stacked.

  When the photoelectric conversion element having such a structure is irradiated with light from the outside of the substrate, the sensitizing dye in the photoelectric conversion layer inside the element is excited to emit electrons. The excited electrons move to the first electrode, and the electrons move to the second electrode through an external circuit and are supplied to the hole transport layer. The oxidized sensitizing dye (by releasing electrons) receives electrons from the hole transport layer and returns to the ground state. By repeating such a cycle, light energy is converted into electrical energy.

Recently, photoelectric conversion elements (solar cells) including a photoelectric conversion layer containing a perovskite compound as a dye (light condensing substance) have been announced one after another. For example, Non-Patent Document 1 discloses a photoelectric conversion element including a photoelectric conversion layer using a CH ₃ NH ₃ PbX ₃ (X═Cl, Br, I) perovskite compound as a dye in a mesoporous metal oxide semiconductor layer. Yes. In Non-Patent Document 2, a perovskite compound layer is formed by co-evaporation of PbI ₂ and CH ₃ NH ₃ I without using a metal oxide semiconductor, and a photoelectric conversion element using this as a photoelectric conversion layer Is disclosed.

Sequential deposition as a route to high-performance perovskite-sensitized solar cells, Nature 499, 316-319 (18 July 2013) Efficient planar heterojunction perovskite solar cells by vapor deposition, Nature 501, 395-398 (19 September 2013)

  However, the photoelectric conversion elements described in Non-Patent Documents 1 and 2 cannot obtain a sufficient short-circuit current density, and further improvements have been demanded.

  This invention is made | formed in view of the said situation, and it aims at providing the photoelectric conversion element which can exhibit a high short circuit current density.

  The present inventors have conducted intensive research to solve the above problems. In that process, the short-circuit current density is significantly increased by forming a photoelectric conversion layer using an organic compound having an oxygen atom, a nitrogen atom, or a sulfur atom that can coordinate with the perovskite compound as a support for the perovskite compound. The present invention has been found to be improved, and the present invention has been completed.

  That is, the photoelectric conversion element of the present invention has a substrate, a first electrode, an electron transport layer, a photoelectric conversion layer containing a dye and a dye support, a hole transport layer, and a second electrode. A pigment | dye contains the compound represented by following formula (1).

(However, R ^{1 to} R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted carbon atom having 3 to 6 carbon atoms. A cycloalkyl group, a polyethylene oxide group having 2 to 6 carbon atoms, or a substituted or unsubstituted aromatic ring-containing group having 4 to 10 carbon atoms, wherein R ^{1 to} R ⁴ are simultaneously hydrogen atoms. X ^{1 to} X ³ each independently represents a halogen atom; and M represents a group 14 atom or transition metal of the periodic table.) And the dye support is an oxygen atom, nitrogen It includes an organic compound having an atom or a sulfur atom and having a weight average molecular weight (Mw) of 500 or more.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the photoelectric conversion element which can exhibit a high short circuit current density.

It is a schematic cross section which shows an example of the photoelectric conversion element of this invention.

  Embodiments of the present invention will be described below. The photoelectric conversion element of the present invention has a substrate, a first electrode, an electron transport layer, a photoelectric conversion layer containing a dye and a dye support, a hole transport layer, and a second electrode. A pigment | dye contains the compound represented by following formula (1).

(However, R ^{1 to} R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted carbon atom having 3 to 6 carbon atoms. A cycloalkyl group, a polyethylene oxide group having 2 to 6 carbon atoms, or a substituted or unsubstituted aromatic ring-containing group having 4 to 10 carbon atoms, wherein R ^{1 to} R ⁴ are simultaneously hydrogen atoms. X ^{1 to} X ³ each independently represents a halogen atom; and M represents a group 14 atom or transition metal of the periodic table.) And the dye support is an oxygen atom, nitrogen It includes an organic compound having an atom or a sulfur atom and having a weight average molecular weight (Mw) of 500 or more.

  As described above, in the conventional photoelectric conversion element using a perovskite compound as a dye, a photoelectric conversion device in which a perovskite compound is supported on a semiconductor layer as a support or a material in which a perovskite compound is deposited (no support) is used. Has come as a conversion layer. However, these photoelectric conversion layers have a problem that the short-circuit current density is low because the amount of the perovskite compound in the photoelectric conversion layer is not sufficient.

  The present invention is characterized in that an organic compound capable of supporting a perovskite compound is used as a support for the dye. The organic compound in the present invention has an oxygen atom, a nitrogen atom, or a sulfur atom. These elements form a coordinate bond with M (group 14 atom or transition metal of the periodic table, for example, Pb) of the perovskite compound represented by the above formula (1). Therefore, by using such an organic compound as a dye support, a sufficient amount of perovskite compound can be supported on the photoelectric conversion layer, and as a result, the short-circuit current density is improved.

  Further, since the photoelectric conversion layer in the present invention uses an organic compound as a dye support, it can be formed by a coating method or the like. Therefore, the photoelectric conversion element of the present invention is advantageous in terms of productivity improvement and cost reduction because the conventional steps such as baking of the semiconductor layer and vapor deposition of the perovskite compound are unnecessary in the manufacturing process.

<Photoelectric conversion element>
The structure of the photoelectric conversion element according to the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of the photoelectric conversion element of the present invention. As shown in FIG. 1, the photoelectric conversion element 10 includes a substrate 1, a first electrode 2, an electron transport layer 3, a photoelectric conversion layer 6, a hole transport layer 7, and a second electrode 8 that is a counter electrode. Here, the photoelectric conversion layer 6 contains the perovskite compound 4 of the formula (1) and a dye support as the dye. In FIG. 1, sunlight enters from the direction of the arrow 9 at the bottom of the figure, but the present invention is not limited to this form, and sunlight may enter from the top of the figure.

  Hereinafter, each component of the photoelectric conversion element according to the present invention and a method for manufacturing the photoelectric conversion element according to the present invention will be described.

[substrate]
The substrate according to the present invention is provided on the light incident direction side, and from the viewpoint of photoelectric conversion efficiency of the photoelectric conversion element, a transparent substrate is preferable, and a transparent conductive substrate having a first electrode formed on the surface is more preferable. The substrate preferably has a light transmittance of 10% or more, still more preferably 50% or more, and particularly preferably 80% to 100%.

  The light transmittance is a visible light wavelength region measured by a method in accordance with “Testing method of total light transmittance of plastic-transparent material” of JIS K 7361-1: 1997 (corresponding to ISO 13468-1: 1996). The total light transmittance at.

  As the substrate, the material, shape, structure, thickness, hardness and the like can be appropriately selected from known materials, but preferably have high light transmittance as described above.

  The said board | substrate can be divided roughly into a board | substrate which has rigidity, such as a glass plate and an acrylic board, and a flexible board | substrate like a film substrate. In the former board | substrate which has rigidity, a glass plate is preferable at a heat resistant point, and the kind of glass in particular is not ask | required. The thickness of the substrate is preferably 0.1 to 100 mm, and more preferably 0.5 to 10 mm.

  Examples of the latter flexible substrate include polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate, and modified polyester, polyethylene (PE) resin films, polypropylene (PP) resin films, and polystyrene resin films. , Polyolefin resin films such as cyclic olefin resins, vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetal resin films such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin films, polysulfone ( PSF) resin film, polyethersulfone (PES) resin film, polycarbonate (PC) resin film, polyamide resin film, polyimide resin film, acrylic resin film Arm, and tri-acetyl cellulose (TAC) resin film. In addition to these resin films, an inorganic glass film may be used as the substrate. The thickness of the substrate is preferably 1 to 1000 μm, and more preferably 10 to 100 μm.

  Any resin film having a transmittance of 80% or more at a visible wavelength (400 to 700 nm) can be particularly preferably applied to the present invention.

  Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, and a polycarbonate film are preferable. More preferred are a stretched polyethylene terephthalate film and a biaxially stretched polyethylene naphthalate film.

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

[First electrode]
The first electrode according to the present invention is disposed between the substrate and the photoelectric conversion layer. Here, the first electrode is provided on one surface which is opposite to the light incident direction of the substrate. As the first electrode, those having a light transmittance of 80% or more, more preferably 90% or more (upper limit: 100%) are preferably used. The light transmittance is the same as that described in the description of the substrate.

The material for forming the first electrode is not particularly limited, and a known material can be used. For example, metals such as platinum, gold, silver, copper, aluminum, rhodium, indium; and SnO ₂ , CdO, ZnO, CTO (CdSnO ₃ , Cd ₂ SnO ₄ , CdSnO ₄ ), In ₂ O ₃ , CdIn ₂ of O ₄ or the like, and these metal oxides and the like. Among these, silver is preferably used as the metal, and a grid-patterned film having openings or a film in which fine particles or nanowires are dispersed and applied is preferably used in order to impart light transmittance. The metal oxide is preferably a composite (dope) material in which one or more selected from Sn, Sb, F and Al are added to the above metal oxide. More preferably, conductive metal oxides such as In ₂ O ₃ (ITO) doped with Sn, SnO ₂ doped with Sb, and SnO ₂ (FTO) doped with F are preferably used. Is most preferred. The amount of the material forming the first electrode applied to the substrate is not particularly limited, but is preferably about 1 to 100 g per 1 m ^{2 of} the substrate.

  The first electrode according to the present invention is preferably a transparent conductive substrate provided on the surface of a transparent substrate, which is a substrate. Here, the substrate on which the first electrode is formed is referred to as a transparent conductive substrate (or first conductive substrate). Also referred to as one electrode substrate).

  Although it does not restrict | limit especially as average thickness of a transparent conductive substrate, The range of 0.1 mm-5 mm is preferable. The surface resistance of the transparent conductive substrate is preferably 50 Ω / □ (square) or less, more preferably 20 Ω / □ (square) or less, and still more preferably 10 Ω / □ (square) or less. is there. The lower limit of the surface resistance of the transparent conductive substrate is preferably as low as possible and need not be specified. However, 0.01Ω / □ (square) or more is sufficient. The preferable range of the light transmittance of the transparent conductive substrate is the same as the preferable range of the light transmittance of the substrate.

[Electron transport layer]
In the photoelectric conversion element according to the present invention, the electron transport layer has a film shape (layer shape) as a short-circuit preventing unit, a sealing unit, and a rectifying function, and is disposed between the first electrode and the photoelectric conversion layer. The electron transport layer is considered to cause charge separation at the interface with the photoelectric conversion layer during light irradiation. In addition, in this specification, what formed the electron carrying layer on the 1st electrode (transparent conductive substrate) formed on the board | substrate is also called a conductive substrate.

  The electron transport layer according to the present invention is preferably porous. More specifically, the porosity C of the electron transport layer is, for example, preferably about 20% or less, more preferably about 5% or less, and still more preferably about 2% or less. . That is, the electron transport layer is preferably a dense layer. Thereby, effects, such as a short circuit prevention and a rectification | straightening effect | action, can be improved more. Here, since the lower limit of the porosity C of the electron transport layer is preferably as small as possible, it is not necessary to specify in particular, but it is usually about 0.05% or more.

  The average thickness (film thickness) of the electron transport layer is, for example, preferably about 0.001 to 10 μm, and more preferably about 0.005 to 0.5 μm. Thereby, the said effect can be improved more.

The constituent material of the electron transport layer according to the present invention is not particularly limited, but an n-type semiconductor can be used. For example, in the case of inorganic substances, zinc, niobium, tin, titanium, vanadium, indium, tungsten, tantalum, zirconium, molybdenum, manganese, iron, copper, nickel, iridium, rhodium, chromium, ruthenium or oxides thereof, and titanic acid Perovskites such as strontium, calcium titanate, barium titanate, magnesium titanate, strontium niobate, or their complex oxides or oxide mixtures, such as CdS, CdSe, TiC, Si ₃ N ₄ , SiC, BN 1 type, or 2 or more types of combinations, such as various metal compounds, can also be used. In the case of organic substances, fullerene or a derivative thereof (for example, phenyl-C61-butyric acid methyl ester ([60] PCBM), phenyl-C61-butyric acid n-butyl ester ([60] PCBnB), phenyl-C61-butyric acid isobutyl ester) ([60] PCBiB), phenyl-C61-butyric acid n-hexyl ester ([60] PCBH), phenyl-C61-butyric acid n-octyl ester ([60] PCBO), diphenyl-C62-bis (butyric acid methyl ester) ( Bis [60] PCBM), phenyl-C71-butyric acid methyl ester ([70] PCBM), phenyl-C85-butyric acid methyl ester ([84] PCBM), thienyl-C61-butyric acid methyl ester ([60] ThCBM), C60 Pyrrolidine tris acid, C60 pyrrolidine tri Acid ethyl ester, N-methylfulleropyrrolidine (MP-C60), (1,2-methanofullerene C60) -61-carboxylic acid, (1,2-methanofullerene C60) -61-carboxylic acid t-butyl ester) , Octaazaporphyrins, etc., perfluoro compounds in which hydrogen atoms of p-type organic semiconductor compounds are substituted with fluorine atoms (for example, perfluoropentacene or perfluorophthalocyanine), naphthalene tetracarboxylic anhydride, naphthalene tetracarboxylic diimide, perylene tetra Examples thereof include aromatic carboxylic acid anhydrides such as carboxylic acid anhydrides and perylene tetracarboxylic acid diimides, and polymer compounds containing the imidized product thereof as a skeleton.

  In particular, when the hole transport layer is a p-type semiconductor, when a metal is used for the electron transport layer, it is preferable to use a material having a work function value smaller than that of the hole transport layer and having a Schottky contact. Moreover, when using a metal oxide for an electron carrying layer, it is preferable to contact a transparent conductive layer and ohmic. At this time, the efficiency of electron transfer from the photoelectric conversion layer to the electron transport layer can be improved by selecting an oxide. Among these, those having electrical conductivity equivalent to that of the photoelectric conversion layer are preferable, and those mainly composed of titanium oxide are more preferable. In this case, the titanium oxide layer may be either anatase-type titanium oxide or a rutile-type titanium oxide having a relatively high dielectric constant.

[Photoelectric conversion layer]
The photoelectric conversion layer according to the present invention contains a dye and a dye support. Here, the dye includes the dye (perovskite compound) of the above formula (1).

(Dye)
The dye is represented by the following formula (1):

A perovskite compound represented by: The dye is supported by coordinate bonding to the dye support, and can be photoexcited to generate an electromotive force when irradiated with light. The perovskite compound of the above formula (1) forms a superlattice structure in which organic ammonium molecular layers (R ^{1 to} R ⁴ ) and inorganic halide layers (X ^{1 to} X ³ ) are alternately stacked, and inorganic halide (X ¹ ˜X ³ ) indicates physical properties as a low-dimensional semiconductor, a magnetic body, and a light emitter.

In the above formula (1), R ^{1 to} R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted carbon atom. A cycloalkyl group having 3 to 8 carbon atoms, a polyethylene oxide group having 2 to 6 carbon atoms, or a substituted or unsubstituted aromatic ring group having 4 to 10 carbon atoms. Here, R ^{1 to} R ⁴ may be the same or different from each other, but R ^{1 to} R ⁴ are not simultaneously hydrogen atoms. Preferably, among R ^{1 to} R ⁴ , 2 or 3 are hydrogen atoms, and 3 are more preferably hydrogen atoms.

The alkyl group in the above formula (1) is a linear or branched alkyl group having a carbon chain length of 1 to 6. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, Examples include 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group. Among these, taking into account the ease of taking a perovskite structure (molecular size of [(R ¹ ) (R ² ) (R ³ ) (R ⁴ ) N]), etc., straight chain or branched having a carbon chain length of 1 to 4 A straight chain alkyl group having a carbon chain length of 1 to 3 is more preferable.

  The cycloalkyl group in the above formula (1) is a cycloalkyl group having 3 to 8 carbon atoms. For example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. are mentioned. Among these, a cycloalkyl group having a carbon chain length of 5 to 7 is preferable.

The polyethylene oxide group having 2 to 6 carbon atoms is represented by the formula: — (CH ₂ CH ₂ O) _x H or the formula: — (CH ₂ CH ₂ O) _x CH ₃ or the formula: —CH ₂ (OCH ₂ CH ₂ ). a group represented by _x H, preferably of the _formula: a group represented by _{-CH 2 (OCH 2 CH 2)} x H. In the above formula, x is an integer of 1 to 3, and preferably 1 or 2.

  The aromatic ring group having 4 to 10 carbon atoms is not particularly limited, and examples thereof include a substituted or unsubstituted phenyl group, naphthyl group, pyridine, thiophene, and furan. Of these, a phenyl group is preferred.

In addition, the term “substituted” in the above formula (1) means that at least one hydrogen atom in the above exemplified alkyl group, cycloalkyl group, and aromatic ring group is substituted with another substituent. Say. In this case, the substituent is not particularly limited as long as the perovskite structure is not impaired, and an alkyl group or an alkoxy group (for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group). , Tert-butoxy group, etc.). The substituent is appropriately selected depending on other components of the dye, for example, the size of “M” or “X ^{1 to} X ³ ” in the above formula (1). For example, when M is lead, it is preferable that the molecular size of [(R ¹ ) (R ² ) (R ³ ) (R ⁴ ) N] is small, considering the high maintainability of the perovskite structure, An alkyl group having 1 to 3 atoms is preferable, and a methyl group is more preferable as a substituent. In addition, the substituent which exists depending on the case is not the same as the substituent. For example, when R ^{1 to} R ⁴ are alkyl groups, they are not further substituted with an alkyl group.

In the case where R ^{1 to} R ⁴ are not hydrogen atoms, the remaining R ^{1 to} R ⁴ are preferably an alkyl group, a polyethylene oxide group having 2 to 6 carbon atoms, or an aromatic ring group, and may be an alkyl group or an aromatic ring group. And more preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group.

Specifically, the [(R ¹ ) (R ² ) (R ³ ) (R ⁴ ) N] moiety in the above formula (1) is methyl ammonium (CH ₃ NH ₃ ), ethyl ammonium (C ₂ H ₅ NH _3), methyl ethyl ammonium _{(CH 3 C 2 H 5 NH} 2), propyl ammonium _{(C 3 H 7 NH 3)} , isopropylammonium _{((CH 3) 2 CHNH 3} ), tetrabutylammonium _{(C 4} H 9 NH ₃ ), pentyl ammonium _{(C 5 H 11 NH 3)} , hexyl ammonium _{(C 6 H 13 NH 3)} ; cyclohexyl ammonium _{(C 6 H 5 NH 3)} ; cyclohexenyl tetraethylammonium _{(C 6 H 9 C 2 H} 4 NH 3 ); methoxyethyl ammonium _{(CH 3 OC 2 H 5 NH} 3); ethoxymethyl ammonium _(C 2 _{H 5} CH ₂ NH _3); phenethylammonium _{(C 6 H 5 C 2 H} 4 NH 3); benzylammonium _{(C 6 H 4 CH 2 NH} 3); benzylamino ammonium _{(NH 2 C 6 H 4 CH} 2 NH 3), Anilinium and pyridylammonium are preferable, and methylammonium (CH ₃ NH ₃ ), ethylammonium (C ₂ H ₅ NH ₃ ), methylethylammonium (CH ₃ C ₂ H ₅ NH ₂ ), propylammonium (C ₃ H ₇ NH ₃ ) and isopropyl ammonium ((CH ₃ ) ₂ CHNH ₃ ) are more preferable.

In the above formula (1), X ^{1 to} X ³ each independently represent a halogen atom. Here, X ^{1 to} X ³ may be the same or different from each other. Here, the halogen atom is not particularly limited, but includes a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Among these, a chlorine atom, a bromine atom, and an iodine atom are preferable, and an iodine atom and bromine are more preferable.

  In the above formula (1), M represents a group 14 atom or transition metal in the periodic table. Among these, germanium (Ge), tin (Sn), lead (Pb), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), palladium (Pd) and europium (Eu) are preferable, and lead (Pb) and tin (Sn) are more preferable.

That is, preferable examples of the dye of the formula (1) include (CH ₃ NH ₃ ) PbI ₃ , (C ₂ H ₅ NH ₃ ) PbI ₃ , (CH ₃ C ₂ H ₅ NH ₂ ) PbI ₃ , (C _{3 H 7 NH 3) PbI 3} , ((CH 3) 2 CHNH 3) PbI 3, [( _{cyclopropyl) NH 3] PbI 3, [} H (CH 2 CH 2 O) CH 2] PbI 3, [C 6 H ₅ NH ₃ ] PbI ₃ , [(Pyridyl) NH ₃ ] PbI ₃ , [(Benzyl) NH ₃ ] PbI ₃ , [(Benzylamino) NH ₃ ] PbI ₃ , (CH ₃ NH ₃ ) PbI _2.7 Br _0.3 , (C ₂ H ₅ NH ₃ ) PbI _2.7 Br _0.3 , (CH ₃ C ₂ H ₅ NH ₂ ) PbI _2.7 Br _0.3 , (C ₃ H ₇ NH ₃ ) PbI _{2 .7} Br _0.3, ((CH _{) 2 CHNH 3) PbI 2.7 Br} 0.3, [( _{cyclopropyl) NH 3] PbI 2.7 Br 0.3} , [H (CH 2 CH 2 O) CH 2] PbI 2.7 Br 0. ₃ , [C ₆ H ₅ NH ₃ ] PbI _2.7 Br _0.3 , [(pyridyl) NH ₃ ] PbI _2.7 Br _0.3 , [(benzyl) NH ₃ ] PbI ₃ , [(benzylamino) NH ₃ ] PbI _2.7 Br _0.3 , (CH ₃ NH ₃ ) PbBr ₃ , (C ₂ H ₅ NH ₃ ) PbBr ₃ , (CH ₃ C ₂ H ₅ NH ₂ ) PbBr ₃ , (C ₃ H ₇ NH ₃ ) PbBr ₃ , ((CH ₃ ) ₂ CHNH ₃ ) PbBr ₃ , [(cyclopropyl) NH ₃ ] PbBr ₃ , [H (CH ₂ CH ₂ O) CH ₂ ] PbBr ₃ , [C ₆ H ₅ NH ₃ ] PbBr ₃ , [(Pyridyl) NH ₃ ] PbBr ₃ , [(Benzyl) NH ₃ ] PbBr ₃ , [(Benzylamino) NH ₃ ] PbBr ₃ , (CH ₃ NH ₃ ) PbI ₂ Cl, (C ₂ H ₅ NH ₃ ) PbI _{2 Cl, (CH 3 C 2} H 5 NH 2) PbI 2 Cl, (C 3 H 7 NH 3) PbI 2 Cl, ((CH 3) 2 CHNH 3) PbI 2 Cl, [( cyclopropyl) _NH 3] PbI ₂ Cl, [H (CH ₂ CH ₂ O) CH ₂ ] PbI ₂ Cl, [C ₆ H ₅ NH ₃ ] PbPbI ₂ Cl, [(pyridyl) NH ₃ ] PbI ₂ Cl, [(benzyl) NH ₃ ] PbI ₂ Cl, [(benzylamino) NH ₃ ] PbI ₂ Cl are preferred, (CH ₃ NH ₃ ) PbI ₃ , (CH ₃ NH ₃ ) PbI _2.7 Br _0.3 , (CH ₃ NH ₃ ) PbBr ₃ and (CH ₃ NH ₃ ) PbI ₂ Cl are more preferred.

  In the present invention, as the dye, the dye of the above formula (1) may be used alone, a plurality of the dyes of the above formula (1) may be used in combination, or other compounds (for example, US Pat. 4,684,537, 4,927,721, 5,084,365, 5,350,644, 5,463,057, 5,525,440, JP-A-7-249790, JP-A-2000-150007, etc.) can also be used as a mixture. Preferably, only the dye of formula (1) described above is used.

  In addition, when the use of the photoelectric conversion element of the present invention is a solar cell described later, two or more kinds of dyes having different absorption wavelengths are used so that the wavelength range of photoelectric conversion can be made as wide as possible to effectively use sunlight. You may use together.

The amount of the dye contained in the photoelectric conversion element of the present invention is not particularly limited, but is preferably 0.01 to 100 mmol / m ² per area of the photoelectric conversion element from the viewpoint of photoelectric conversion efficiency and the like. more preferably 03~50mmol / ^{m 2,} further preferably 0.05~20mmol / ^{m 2.}

(Dye support)
The dye support includes an organic compound that carries the dye of formula (1) (perovskite compound) and can be formed as a photoelectric conversion layer. More specifically, the dye support is an oxygen atom (O) capable of coordinating with M (group 14 atom or transition metal of the periodic table, eg Pb) of the dye of formula (1) (perovskite compound), An organic compound containing at least one of a nitrogen atom (N) or a sulfur atom (S) and having a weight average molecular weight (Mw) of 500 or more is essential.

  The content of oxygen atoms (O), nitrogen atoms (N), and sulfur atoms (S) contained in the organic compound is not particularly limited, but when the total number of carbon atoms in the organic compound is 1, oxygen atoms The total number of (O), nitrogen atoms (N), and sulfur atoms (S) is preferably 0.1 to 1, and more preferably 0.33 to 0.67. Since the organic compound contains an oxygen atom (O), a nitrogen atom (N), and a sulfur atom (S) in the above proportion, the support of the dye (perovskite compound) of the formula (1) is increased. Can contribute to improvement.

  Such an organic compound is not particularly limited, but is selected from the group consisting of polyether, polyester, polyphosphate ester, polyamide, polyimide, polycarbonate, polythioester, polythiocarbonate, and sulfur-containing polyisopropylene (vulcanized rubber). It is preferable that at least one polymer compound is used.

  The polyether has a repeating structure represented by the following formula (2).

  The polyester has a repeating structure represented by the following formula (3).

  Polyamide has a repeating structure represented by the following formula (4).

  Polyamide has a repeating structure represented by the following formula (5).

  Polycarbonate has a repeating structure represented by the following formula (6).

  The polythioester has a repeating structure represented by the following formula (7).

  The polythiocarbonate has a repeating structure represented by the following formula (8).

In the above formulas (2) to (6), R ^{5 to} R ⁸ and R ^{10 to} R ¹³ are not particularly limited, but are each independently a substituted or unsubstituted straight chain having 1 to 10 carbon atoms or A branched alkylene group, a substituted or unsubstituted cycloalkylene group having 3 to 1 carbon atoms, a substituted or unsubstituted arylene group having 6 to 16 carbon atoms, a group in which a plurality of these are linked, or these Is preferably a group in which a plurality of are connected via an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a boron atom.

  Examples of the alkylene group include methylene group, ethylene group, trimethylene group, tetramethylene group, propylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group and the like.

  Examples of the cycloalkylene group include a cyclocyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and an adamantyl group.

  Examples of the arylene group include a phenylene group, a naphthylene group, a biphenylene group, an anthracenylene group, and a phenanthrene group.

In the above formula (5), R ⁹ is not particularly limited, but each independently represents a substituted or unsubstituted tetravalent aromatic group having 6 to 16 carbon atoms such as benzene, naphthalene, and anthracene. A group in which four hydrogens are removed is preferable.

In addition, substituents optionally present in these groups include alkyl groups, cycloalkyl groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups, acyl groups, alkoxycarbonyl groups, (alkyl) amino groups, alkoxy groups. , Cycloalkyloxy group, aryloxy group, aryloxycarbonyl group, alkyl ester group, ester group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio Group, silyl group (—SiH ₃ ), sulfonyl group, sulfinyl group, ureido group, phosphoric acid amide group, halogen atom, hydroxyl group (—OH), mercapto group (—SH), cyano group (—CN), sulfo group (-SO ₃ H), carboxyl group (—COOH), nitro group (—NO ₂ ), hydroxamic acid group (—C (═O) —NH—OH), sulfino group (—S (═O) OH), hydrazino group (— NHNH ₂ ), imino group and the like.

  Specific organic compounds include polyethylene glycol, polytrimethylene glycol, polypropylene glycol; polyglycolic acid (polyglycolide), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT). ), Polyethylene naphthalate (PEN), polybutylene naphthalate (PBN); nylon 6 (polycondensate of caprolactam), nylon 11 (polycondensate of undecane lactam), nylon 12 (polycondensate of lauryl lactam), nylon 66 (co-condensation polymer of hexamethylene diamine and adipic acid), nylon 610 (co-condensation polymer of hexamethylene diamine sebacic acid), nylon 6T (co-condensation polymer of hexamethylene diamine and terephthalic acid), na Ron 6I (copolycondensation polymer of hexamethylenediamine and isophthalic acid), nylon 9T (copolycondensation polymer of nonanediamine and terephthalic acid), nylon M5T (copolycondensation polymer of methylpentadiamine and terephthalic acid), nylon 612 (caprolactam and lauryl lactam copolymer). Kevlar (registered trademark, poly-p-phenylene terephthalamide) Nomex (registered trademark, poly-m-phenyleneisophthalamide); Kapton (registered trademark) H (copolycondensate of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether) Bisphenol A type polycarbonate and the like.

  In addition, biopolymer compounds such as nucleic acids (DNA, RNA), polypeptides, and polysaccharides may be used as the organic compound.

  Among these organic compounds, M (group 14 atom or transition metal of the periodic table such as Pb) of the dye of the formula (1) (perovskite compound) and a stable 5-membered ring coordination structure or 6-membered ring coordination It preferably has a partial structure of O—C—C—O or O—C—C—C—O that can form a coordination structure. Specifically, polyethylene glycol, polytrimethylene glycol, polypropylene glycol, polyglycolic acid (polyglycolide), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and the like. It is preferable. Since such an organic compound is excellent in the carrying | support property of a pigment | dye, it can improve a short circuit current density more.

  The weight average molecular weight (MW) of the organic compound is essentially 500 or more, preferably 500 to 100,000, and more preferably 2000 to 10,000. By making the said weight average molecular weight (MW) into the said range, the film forming property of a photoelectric converting layer can improve. In addition, the value measured by standard polystyrene conversion using GPC shall be employ | adopted for the weight average molecular weight (MW) in this specification.

  Although there is no restriction | limiting in particular in content of the said pigment | dye support body in the photoelectric converting layer of this invention, It is preferable that it is 5-400 mass parts with respect to 100 mass parts of content of the said pigment | dye, 10-100 mass parts More preferably, it is more preferably 10 to 50 parts by mass. When the content of the dye support is 5 parts by mass or more, the photoelectric conversion layer can be formed satisfactorily. On the other hand, when the content of the dye support is 400 parts by mass or less, the content of the dye does not decrease too much, and sufficient photoelectric conversion efficiency can be exhibited.

  In the present invention, the thickness of the photoelectric conversion layer is not particularly limited, but is usually 0.1 to 20 μm, and preferably 0.5 to 2 μm. When the film thickness is in such a range, a sufficiently high photoelectric conversion efficiency can be exhibited.

(Method for producing photoelectric conversion layer)
In the present invention, the method for producing the photoelectric conversion layer is not particularly limited, but mainly includes the following three methods. Hereinafter, a method for producing a photoelectric conversion layer will be described by using as an example a case where (CH ₃ NH ₃ ) PbI ₃ is used as a dye.

  Method (1): A method in which after preparing a dye precursor, a liquid containing the dye precursor and the dye support (organic compound) is applied onto the electron transport layer, followed by heat treatment / drying (one-step application method).

In the method (1), a dye precursor is first prepared. When (CH ₃ NH ₃ ) PbI ₃ is used as a dye, CH ₃ NH ₃ I can be obtained by dissolving methylamine and hydroiodic acid in a suitable solvent and concentrating and drying the solution. Next, a dye precursor solution is prepared by mixing CH ₃ NH ₃ I and PbI ₂ in a suitable solvent.

  Subsequently, the dye precursor and the dye support are mixed in an appropriate solvent, and the dye precursor solution is applied onto the electron transport layer. The coating method in this case is not particularly limited, and examples thereof include known methods such as a dropping method, a dipping method, a doctor blade method, a squeegee method, a spin coating method, a screen printing method, and an ink jet method.

  Then, the perovskite compound is formed by heat-treating / drying the applied dye precursor solution. The conditions for the heat treatment / drying are not particularly limited, but preferably on an apparatus (for example, a hot plate) heated to 40 to 500 ° C., more preferably 60 to 200 ° C., and preferably 1 to 300 minutes. Leave for 5 to 120 minutes and heat treat / dry. Thereby, the photoelectric converting layer by which a pigment | dye is carry | supported in the pigment | dye support body layer is produced.

Method (2): A mixed solution of a dye support (organic compound) and PbI ₃ is applied on an electron transport layer and dried, and then immersed in a solution containing CH ₃ NH ₃ I, followed by heat treatment / drying. Method (coating + impregnation method).

In the method (2), first, the dye support and PbI ₂ are dissolved in an appropriate solvent, and the obtained solution is applied onto the electron transport layer. The coating method at this time is the same as the coating method in the above method (1). Then, by drying this, a film in which PbI ₂ is supported on the dye support is formed on the electron transport layer. In addition, the drying conditions in this case are not particularly limited, but preferably on an apparatus (for example, a hot plate) heated to 40 to 150 ° C., more preferably 60 to 100 ° C., and preferably 1 to 120 minutes. Leave for 5 to 60 minutes and dry.

Next, the film in which PbI ₂ is supported on the dye support formed on the electron transport layer is immersed in a solution containing CH ₃ NH ₃ I, and is heat-treated / dried. Although the conditions in the case of the said immersion are not restrict | limited in particular, 10-100 degreeC is preferable and the process temperature has more preferable 15-40 degreeC. The treatment time is preferably 5 to 120 seconds, more preferably 5 to 30 seconds. In particular, the treatment is preferably performed at room temperature (25 ° C.) for 5 to 30 seconds, particularly 10 to 20 seconds. The conditions for the heat treatment / drying after the immersion are the same as those for the heat treatment / drying in the above method (1). Thereby, the photoelectric converting layer formed by carrying | supporting a pigment | dye to a pigment | dye support body is produced.

Method (3): A solution containing a dye support is applied onto the electron transport layer and dried to form a dye support film. A method in which a solution containing PbI ₂ is applied and dried thereon, and further immersed in a solution containing CH ₃ NH ₃ I, followed by heat treatment / drying (two-step application + impregnation method).

  In method (3), the dye support is dissolved in a suitable solvent, and the resulting solution is applied onto the electron transport layer and dried. The coating and drying method at this time is the same as the above method (1). Thereby, the film | membrane of a pigment | dye support body is formed on an electron carrying layer.

Next, a solution containing PbI ₂ is applied to the film of the dye support and dried. The coating and drying method at this time is the same as the above method (1). Thereby, PbI ₂ is supported on the membrane of the dye support.

Thereafter, in the same manner as in the above method (2), the above-mentioned dye support film carrying PbI ₂ is dipped in a solution containing CH ₃ NH ₃ I and heat-treated / dried. Thereby, the photoelectric converting layer formed by carrying | supporting a pigment | dye to a pigment | dye support body is produced.

  Any of the methods (1) to (3) may be adopted, but the method (1) is preferably adopted from the viewpoint of the degree of filling of the perovskite molecules into the dye support.

  In the above methods (1) to (3), the solvent used for dissolving the dye raw material, the dye support and the like is not particularly limited, but the moisture and gas dissolved in the solvent prevent the adsorption of the dye and the like. In order to prevent this, it is preferable to deaerate and purify in advance. Solvents preferably used in the dissolution of the dye material and dye support, etc. include nitrile solvents such as acetonitrile, alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, and t-butyl alcohol, β-propiolactone, Lactone solvents such as γ-butyrolactone and δ-valerolactone, ketone solvents such as acetone and methyl ethyl ketone, ether solvents such as diethyl ether, diisopropyl ether, tetrahydrofuran and 1,4-dioxane, methylene chloride, 1,1,2 -Halogenated hydrocarbon solvents such as trichloroethane, dimethylformamide, dimethyl sulfoxide and the like. These solvents may be used alone or in combination of two or more. Among these, acetonitrile, methanol, ethanol, n-propanol, isopropanol, t-butyl alcohol, γ-butyrolactone, acetone, methyl ethyl ketone, tetrahydrofuran, methylene chloride, dimethylformamide and mixed solvents thereof such as acetonitrile / methanol mixed solvent, An acetonitrile / ethanol mixed solvent and an acetonitrile / t-butyl alcohol mixed solvent are preferable.

[Hole transport layer]
The hole transport layer has a function of supplying electrons to the sensitizing dye oxidized by photoexcitation to reduce the hole, and transporting holes generated at the interface with the sensitizing dye to the second electrode.

  The hole transport layer according to the present invention is mainly composed of a redox electrolyte dispersion and a p-type compound semiconductor (charge transport agent) as a hole transport material.

Examples of the redox electrolyte include I ⁻ / I ₃ ⁻ system, Br ⁻ / Br ₃ ⁻ system, and quinone / hydroquinone system. Such redox electrolyte can be obtained by a conventionally known method, for example, I ^- / I ₃ ^- system electrolyte can be obtained by mixing an ammonium salt of iodine and iodine. These dispersions are called liquid electrolytes when they are in solution, solid polymer electrolytes when dispersed in a polymer that is solid at room temperature, and gel electrolytes when dispersed in a gel-like substance. When a liquid electrolyte is used as the hole transport layer, an electrochemically inert solvent is used as the solvent, for example, acetonitrile, valeronitrile, propylene carbonate, ethylene carbonate, or the like. Examples of the solid polymer electrolyte include the electrolyte described in JP-A No. 2001-160427, and examples of the gel electrolyte include the electrolyte described in “Surface Science” Vol. 21, No. 5, pages 288 to 293.

  As the p-type compound, monomers such as aromatic amine derivatives, pyridine derivatives, thiophene derivatives, pyrrole derivatives, and stilbene derivatives, and oligomers (particularly dimers and trimers) and polymers containing the monomers can be used. Since the monomer and oligomer have a relatively low molecular weight, they are highly soluble in a solvent such as an organic solvent, and can be easily applied to the photoelectric conversion layer. On the other hand, for the polymer, a method of applying the polymer in the form of a prepolymer to the photoelectric conversion layer and polymerizing the polymer on the photoelectric conversion layer may be simple. There is no restriction | limiting in particular as the said polymerization method, For example, well-known polymerization methods, such as the method of Unexamined-Japanese-Patent No. 2000-106223, are applicable. Specifically, an electropolymerization method comprising at least a working electrode and a counter electrode and reacting by applying a voltage between both electrodes, a chemical polymerization method using a polymerization catalyst, light irradiation alone or a polymerization catalyst, heating, electrolysis, etc. The combined photopolymerization method etc. are mentioned. Of these, the electrolytic polymerization method is preferably used. A photoelectric conversion element containing a p-type compound obtained by electrolytic polymerization can have a particularly high open circuit voltage (Voc).

  The monomer and oligomer as the p-type compound are not particularly limited, and known compounds can be used. For example, as an aromatic amine derivative, for example, N, N, N ′, N′-tetraphenyl-4,4′-diaminobiphenyl; N, N′-diphenyl-N, N′-bis (3-methylphenyl) )-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p) -Tolylaminophenyl) cyclohexane; N, N, N ', N'-tetra-p-tolyl-4,4'-diaminobiphenyl; 1,1-bis (4-di-p-tolylaminophenyl) -4- Bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N′-di (4-methoxyphene); ) -4,4′-diaminobiphenyl; N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether; 4,4′-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenyl) Vinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole; 2,2 ′, 7,7′-tetrakis (N, N′-di (4-methoxyphenyl) amine ) -9,9′-spirobifluorene (Spiro-OMeTAD) and the like. In addition, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD) having two condensed aromatic rings described in US Pat. No. 5,061,569 in the molecule. ), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] in which three triphenylamine units described in JP-A-4-308688 are linked in a starburst type Triphenylamine (MTDATA), etc. may be used, and among these, it is preferable to use an aromatic amine derivative monomer excellent in hole transporting ability, particularly a triphenyldiamine derivative. A polymer material introduced or having a polymer main chain may be used.

  The charge transfer agent preferably has a large band gap so as not to prevent dye absorption. The band gap of the charge transfer agent used in the present invention is preferably 2 eV or more, and more preferably 2.5 eV or more. Further, the ionization potential of the charge transport agent needs to be smaller than the dye adsorption electrode ionization potential in order to reduce the dye hole. Although the preferred range of the ionization potential of the charge transport agent used in the hole transport layer varies depending on the dye used, it is generally preferably 4.5 eV or more and 5.5 eV or less, and more preferably 4.7 eV or more and 5.3 eV or less.

  As the charge transport agent, an aromatic amine derivative or a conductive polymer having excellent hole transport ability is preferable. For this reason, photoelectric conversion efficiency can be improved more by comprising a hole transport layer mainly with an aromatic amine derivative and a conductive polymer. As the aromatic amine derivative, it is particularly preferable to use a triphenylamine derivative. Triphenylamine derivatives are particularly excellent in the ability to transport holes among aromatic amine derivatives. Moreover, such an aromatic amine derivative may use any of a monomer, an oligomer, a prepolymer, and a polymer, and may mix and use these. Monomers, oligomers, and prepolymers have a relatively low molecular weight, and thus have high solubility in solvents such as organic solvents. For this reason, when forming a positive hole transport layer by the apply | coating method, there exists an advantage that preparation of a positive hole transport layer material can be performed more easily. Among these, it is preferable to use a dimer or a trimer as the oligomer.

  Specific aromatic tertiary amine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′-bis (3- Methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di) -P-tolylaminophenyl) cyclohexane; N, N, N ', N'-tetra-p-tolyl-4,4'-diaminobiphenyl; 1,1-bis (4-di-p-tolylaminophenyl)- 4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N′-di (4 -Methoxyphenyl -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N- Tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) Benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two condensed aromatic rings described in US Pat. No. 5,061,569 For example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), described in JP-A-4-308688 That triphenylamine units are linked to three starburst 4,4 ', 4 "- tris [N- (3- methylphenyl) -N- phenylamino] triphenylamine (MTDATA) and the like.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  The conductive polymer contains a compound represented by the following chemical formula (A) or a polymer formed by polymerizing a multimer of the compound (hereinafter also simply referred to as “polymer”).

In the above chemical formula (A),
Y ₁ and Y ₂ are each a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, an aryl group having 6 to 24 carbon atoms, —OR ₁₄ group, —SR ₁₅ group, —SeR ₁₆ group, or -Represents a TeR ₁₇ group. Y ₁ and Y ₂ may be the same or different. R _{14 to} R ₁₇ represent a hydrogen atom or a linear or branched alkyl group having 1 to 24 carbon atoms. Here, Y ₁ and Y ₂ may be bonded to each other to form a ring structure.

The linear or branched alkyl group having 1 to 24 carbon atoms as Y ₁ , Y ₂ and R _{14 to} R ₁₇ is not particularly limited, and is the same as the alkyl group in the chemical formula (1).

Of these, Y ₁ and Y _2, preferably a linear or branched alkyl group having 6 to 18 carbon atoms, more preferably straight chain alkyl group having 6 to 18 carbon atoms. When the polymer has a long chain (for example, having 6 to 18 carbon atoms) alkyl group, the alkyl group acts as a functional group that inhibits self-aggregation and can suppress the formation of a self-aggregated structure. Is estimated to be improved.

_As the R 14 _{to R 17,} preferably a linear or branched alkyl group having 1 to 5 carbon atoms, preferably an alkyl group having a straight chain of 1 to 5 carbon atoms.

As the Y ₁ and Y _2, the aryl group having 6 to 24 carbon atoms is not particularly limited, for example, a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, an anthryl group, pyrenyl group, azulenyl group, acenaphthylenyl group , Terphenyl group, phenanthryl group and the like. Among these, a phenyl group, a biphenyl group, and a fluorenyl group are preferable, and a phenyl group and a fluorenyl group are more preferable.

In Y ₁ , Y ₂ and R _{14 to} R ₁₇ , at least one of hydrogen atoms in the “linear or branched alkyl group having 1 to 24 carbon atoms” and the “aryl group having 6 to 24 carbon atoms” is substituted. It may be substituted with a group.

In Y ₁ , Y ₂ and R _{14 to} R ₁₇ , the substituent is a halogen atom, each substituted or unsubstituted linear or branched alkyl group having 1 to 24 carbon atoms, or hydroxyalkyl having 1 to 24 carbon atoms. Group, an alkoxy group having 1 to 24 carbon atoms, an acyl group having 1 to 24 carbon atoms, an aryl group having 6 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, an amino group, and a heteroaryl having 2 to 24 carbon atoms Selected from the group consisting of groups.

  Here, the halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  The linear or branched alkyl group having 1 to 24 carbon atoms is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, n-octyl Group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-t-butyl 2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, n -Tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, n -Tetracosyl group etc. are mentioned. Among these, a linear or branched alkyl group having 4 to 18 carbon atoms is preferable, and a linear or branched alkyl group having 8 to 12 carbon atoms is more preferable.

  Although it does not restrict | limit especially as a C1-C24 hydroxyalkyl group, For example, there exist a hydroxymethyl group and a hydroxyethyl group.

  The alkoxy group having 1 to 24 carbon atoms may be linear or branched, and is not particularly limited. For example, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, Isobutoxy group, sec-butoxy group, tert-butoxy group, n-pentyloxy group, isopentyloxy group, tert-pentyloxy group, neopentyloxy group, 1,2-dimethylpropoxy group, n-hexyloxy group, iso Hexyloxy group, 1,3-dimethylbutoxy group, 1-isopropylpropoxy group, 1,2-dimethylbutoxy group, n-heptyloxy group, 1,4-dimethylpentyloxy group, 3-ethylpentyloxy group, 2- Methyl-1-isopropylpropoxy group, 1-ethyl-3-methylbutoxy group, n-octyloxy 2-ethylhexyloxy group, 3-methyl-1-isopropylbutoxy group, 2-methyl-1-isopropoxy group, 1-t-butyl-2-methylpropoxy group, n-nonyloxy group, 3,5,5- Trimethylhexyloxy group, n-decyloxy group, isodecyloxy group, n-undecyloxy group, 1-methyldecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n -Pentadecyloxy group, n-hexadecyloxy group, n-heptadecyloxy group, n-octadecyloxy group, n-nonadecyloxy group, n-eicosyloxy group, n-heneicosyloxy group, n-docosyloxy group , N-tricosyloxy group, n-tetracosyloxy group and the like. Among these, a linear or branched alkyl group having 1 to 8 carbon atoms is preferable, and a methoxy group, an ethoxy group, an n-hexyloxy group, and an n-octadecyloxy group are more preferable.

  The acyl group having 1 to 24 carbon atoms may be linear or branched, and is not particularly limited. For example, formyl group, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexyl Examples include carbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group and the like. Among these, a C2-C18 linear or branched acyl group is preferable, and an acetyl group is more preferable.

The aryl group having 6 to 24 carbon atoms is not particularly limited and has the same definition as the aryl group in Y ₁ and Y ₂ described above.

  The alkenyl group having 2 to 24 carbon atoms may be linear or branched and is not particularly limited. For example, a vinyl group, an allyl group, a 1-propenyl group, an isopropenyl group, and a 1-butenyl group. 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group, 2-heptenyl group , 5-heptenyl group, 1-octenyl group, 3-octenyl group, 5-octenyl group and the like. Among these, a linear or branched alkenyl group having 2 to 18 carbon atoms is preferable, and a 1-propenyl group is more preferable.

The substituent for Y ₁ , Y ₂ and R _{14 to} R ₁₇ is preferably a linear alkyl group having 6 to 18 carbon atoms, and more preferably an n-octyl group.

  Preferable examples of the compound represented by the chemical formula (A) include the following compounds (H1-1) to (H1-7). In the present invention, compounds having partial structures of the following compounds (H1-1) to (H1-7) are preferably used as the conductive polymer. However, the present invention is not limited to these. Moreover, in the following Examples, the polymer which comprises a conductive polymer is prescribed | regulated by the following symbol.

  The terminal of the polymer is not particularly limited and is appropriately defined depending on the type of raw material (monomer, dimer, multimer, etc.) used, and is usually a hydrogen atom. Here, the polymer used in the present invention may be formed only from the compound represented by the chemical formula (A), or from the compound represented by the chemical formula (A) and other monomers. It may be formed. Preferably, it is formed only from the compound represented by the chemical formula (A). In this case, the polymer may be formed only from a single type of compound represented by the chemical formula (A), or may be formed from a plurality of types of compounds represented by the chemical formula (A). Also good.

  Moreover, as another monomer, if it does not inhibit the characteristic of the polymer which concerns on this invention, it will not restrict | limit, A well-known monomer can be used. Specific examples include monomers such as pyrrole derivatives or furan derivatives and thiadiazole, and monomers having a π-conjugated structure.

  The polymer used in the present invention comprises one or more compounds represented by the above chemical formula (A) or a multimer of these compounds together with other monomers, if necessary, as a metal as a polymerization catalyst. It can be obtained by polymerization or copolymerization in the presence of a complex.

  Here, the compound (monomer) illustrated above can be used as a compound represented by the said Chemical formula (A). In addition to the above, a multimerized compound such as a dimer or a trimer of the compound represented by the chemical formula (A) (oligomerized compound; hereinafter, collectively referred to as “multimer”), It can be used for the above polymerization or copolymerization.

  For example, dimers (H2-1) to (H2-7) of the compounds (H1-1) to (H1-7) can be preferably used.

  Thus, it is preferable to use a multimer such as a dimer because the oxidation potential at the time of polymer formation is reduced and the synthesis rate of the polymer is shortened as compared with the case of using a monomer. The oligomerized compounds of these monomers are described in, for example, J. Org. R. Reynolds et. al. , Adv. Mater. , 11, 1379 (1999) or a method obtained by appropriately modifying the method. In addition, the monomer dimer is described in T.W. M.M. Swager et. al. , Journal of the American Chemical Society, 119, 12568 (1997), or a method obtained by appropriately modifying the method.

(Polymer polymerization method)
The polymerization method is not particularly limited, and for example, a known polymerization method such as the method described in JP-A No. 2000-106223 can be applied. Specifically, a chemical polymerization method using a polymerization catalyst, an electropolymerization method in which at least a working electrode and a counter electrode are provided and a reaction is performed by applying a voltage between both electrodes, light irradiation alone or a polymerization catalyst, heating, electrolysis, etc. The combined photopolymerization method etc. are mentioned. Among these, a polymerization method using an electrolytic polymerization method is preferable, and a photopolymerization method combining an electrolytic polymerization method and light irradiation is more preferable. By using a combination of an electropolymerization method and a photopolymerization method of polymerizing by irradiating light, a polymer layer can be densely formed on the titanium oxide surface.

  When a polymer is obtained by an electrolytic polymerization method, the synthesis of the polymer directly leads to the formation of the hole transport layer. That is, the following electrolytic polymerization method is performed. In general, a mixture containing a monomer constituting the polymer, a supporting electrolyte, a solvent, and, if necessary, an additive is used.

  The polymer as the p-type compound and the prepolymer that is a raw material of the polymer are not particularly limited, and known compounds can be used. When forming a polymer by electrolytic polymerization on a photoelectric conversion layer using a prepolymer, polymerization may be performed using a mixture containing a supporting electrolyte, a solvent, and, if necessary, an additive together with the prepolymer.

  Here, the solvent is not particularly limited as long as it can dissolve the supporting electrolyte and the monomer or multimer thereof, but it is preferable to use an organic solvent having a relatively wide potential window. Specifically, polar solvents such as tetrahydrofuran (THF), butylene oxide, chloroform, cyclohexanone, chlorobenzene, acetone, various alcohols, dimethylformamide (DMF), acetonitrile, dimethoxyethane, dimethyl sulfoxide, hexamethylphosphoric triamide, And organic solvents such as aprotic solvents such as propylene carbonate, dichloromethane, o-dichlorobenzene, and methylene chloride. Alternatively, water or other organic solvents may be added to the above solvent as necessary to use as a mixed solvent. Moreover, the said solvent may be used independently or may be used with the form of a 2 or more types of mixture.

As the supporting electrolyte, those capable of ionization are used, and are not limited to specific ones, but those having high solubility in a solvent and being less susceptible to oxidation and reduction are preferably used. Specifically, lithium perchlorate (LiClO _4), lithium tetrafluoroborate, tetrabutylammonium _{perchlorate, Li [(CF 3 SO 2} ) 2 N], (n-C 4 H 9) 4 NBF 4 _{, (n-C 4 H 9} ) 4 NPF 4, p- toluenesulfonate, salts such as dodecylbenzene sulfonate may be preferably mentioned. Alternatively, a polymer electrolyte described in JP-A-2000-106223 (for example, PA-1 to PA-10 in the same publication) may be used as a supporting electrolyte, and the supporting electrolyte is used alone. Or may be used in the form of a mixture of two or more.

Examples of the additive that can be added to the hole transport layer include N (PhBr) ₃ SbCl ₆ , NOPF ₆ , SbCl ₅ , I ₂ , Br ₂ , HClO ₄ , (n—C ₄ H ₉ ) ₄ ClO ₄ , Trifluoroacetic acid, 4-dodecylbenzenesulfonic acid, 1-naphthalenesulfonic acid, FeCl ₃ , AuCl ₃ , NOSbF ₆ , AsF ₅ , NOBF ₄ , LiBF ₄ H 1-3 [PMo ₁₂ O ₄₀ ], 7, 7, 8, Acceptor dopants such as 8-tetracyanoquinodimethane (TCNQ), diarylamine, triarylamine, pyridine, 4-tert-butylpyridine, polyvinylpyridine, quinoline, piperidine, amidine and other organic bases, trap holes Various additives such as hard-to-bond binder resins and leveling agents, etc. It is. The above additives may be used alone or in the form of a mixture of two or more.

Next, the substrate on which the first electrode (transparent conductive film), the electron transport layer and the photoelectric conversion layer are formed is immersed in this electrolytic polymerization solution, the photoelectric conversion layer 6 is used as a working electrode, a platinum wire or a platinum plate is used as a counter electrode, Further, it is performed by a direct current electrolysis method using Ag / AgCl, Ag / AgNO ₃ or the like as a reference electrode. The concentration of the monomer or its multimer in the electrolytic polymerization solution is not particularly limited, but is preferably about 0.1 to 1000 mmol / L, more preferably about 0.5 to 100 mmol / L, and more preferably 1 to 20 mmol. / L is particularly preferable. In addition, the supporting electrolyte concentration is preferably about 0.01 to 10 mol / L, and more preferably about 0.1 to 2 mol / L. As the applied current ^density, it is more desirable is preferably in the range of ^{0.01mA / cm 2 ~1000mA / cm 2} , in particular in the range of ^{1mA / cm 2 ~500mA / cm 2} . The holding voltage is preferably −0.5 to + 0.2V, and more preferably −0.3 to 0.0V. The temperature range of the electrolytic polymerization solution is suitably a range in which the solvent does not solidify or bump, and is generally -30 ° C to 80 ° C. By performing electrolytic polymerization while performing light irradiation in this manner, a polymer layer can be densely formed on the surface of the photoelectric conversion layer. Note that conditions such as electrolysis voltage, electrolysis current, electrolysis time, and temperature depend on the materials used, and can be appropriately selected according to the required film thickness.

  Ascertaining the degree of polymerization of a polymer is difficult with a polymer obtained by electrolytic polymerization, but the solvent solubility of the hole transport layer formed after polymerization is greatly reduced. Can be determined by immersing the hole transport layer in tetrahydrofuran (THF), which is a solvent capable of dissolving the compound of the chemical formula (A) or a multimer of the compound, and determining the solubility. Specifically, 10 mg of the compound (polymer) is taken into a 25 ml sample bottle, 10 ml of THF is added, and ultrasonic waves (25 kHz, 150 W, ultrasonic industry, COLLECTOR CURRENT 1.5A, made by ultrasonic industry 150) are added. When the compound dissolved is less than 5 mg when irradiated for 1 minute, it is defined as polymerized. Preferably, the solubility when the hole transport layer is immersed in tetrahydrofuran (THF) is 0.1 to 3 mg.

  On the other hand, when a polymer is formed by chemical polymerization on a photoelectric conversion layer using a prepolymer (for example, a monomer represented by the chemical formula (A) or a multimer thereof), a polymerization catalyst, Polymerization can be carried out using a mixture containing a solvent and an additive such as a polymerization rate adjusting agent, if necessary.

  The polymerization catalyst is not particularly limited, and examples thereof include iron (III) chloride (iron (III) chloride), iron (III) tris-p-toluenesulfonate (iron (III) tris-p-toluenesulfate), p-dodecyl. Iron (III) benzenesulfonate (iron (III) p-dedodecylbenzenesulfonate), iron (III) methanesulfonate (iron (III) methanesulfonate), iron (III) p-ethylbenzenesulfonate (iron (III) p-ethylbenzenesulfonate) And iron (III) naphthalene sulfonate (iron (III) naphthalenesulfonate) and hydrates thereof.

  In addition to the polymerization catalyst, a polymerization rate modifier may be used for chemical polymerization. The polymerization rate adjusting agent is not particularly limited, but is not particularly limited as long as there is a weak complexing agent for trivalent iron ions in the polymerization catalyst and the polymerization rate is reduced so that a film can be formed. For example, when the polymerization catalyst is iron (III) chloride and its hydrate, aromatic oxysulfonic acid such as 5-sulfosalicylic acid can be used. In addition, the polymerization catalyst is iron (III) tris-p-toluenesulfonate, iron (III) p-dodecylbenzenesulfonate, iron (III) methanesulfonate, iron (III) p-ethylbenzenesulfonate, iron naphthalenesulfonate. Examples of (III) and hydrates thereof include imidazole.

  The reaction conditions for the above-mentioned chemical polymerization vary depending on the type, ratio, and concentration of the prepolymer, polymerization catalyst, and polymerization rate regulator used, the thickness of the liquid film at the applied stage, and the desired polymerization rate. In the case of heating in air, the heating temperature is preferably 25 to 120 ° C. and the heating time is preferably 1 minute to 24 hours.

  After the polymer is synthesized, it may be contained in a coating solution containing the polymer and supplied onto the photoelectric conversion layer, but may be polymerized on the photoelectric conversion layer to form a hole transport layer. This is a preferred embodiment. That is, it is preferable to perform polymerization of monomers or their multimers on the photoelectric conversion layer.

  In this case, a hole transport layer forming solution containing a monomer of the chemical formula (A) or a multimer thereof, a supporting electrolyte or a polymerization catalyst, a polymerization rate adjusting agent, other additives, and a solvent is used. As the solvent for the hole transport layer forming solution, those exemplified as the solvent for the electrolytic polymerization solution can be used.

  In the solution for forming a hole transport layer, the total concentration of the above components is the monomer of the chemical formula (A) to be used or a multimer thereof, the polymerization catalyst, the polymerization rate adjusting agent, and other additives. The mass concentration (solid content concentration) is generally in the range of 1 to 50% by weight, although it varies depending on the type, the amount ratio, the conditions for the coating method and the desired film thickness after polymerization.

  After the hole transport layer forming solution is applied onto the photoelectric conversion layer by a coating method, or while the photoelectric reaction layer is immersed in the hole transport layer forming solution, a polymerization reaction is performed.

  The conditions for the polymerization reaction are: the monomer of the above chemical formula (A) or its multimer, the type of the polymerization catalyst, and the polymerization rate modifier, the ratio, concentration, and the liquid film at the applied stage. As a preferable polymerization condition, the heating temperature in the case of heating in air is preferably in the range of 25 to 120 ° C., and the heating time is in the range of 1 minute to 24 hours.

  The coating method is not particularly limited, and a known coating method can be used similarly or appropriately modified. Specifically, dipping, dripping, doctor blade, spin coating, brush coating, spray coating, roll coater, air knife coating, curtain coating, wire bar coating, gravure coating, and an extension using a hopper described in US Pat. No. 2,681,294 Various coating methods such as a rouge coating and a multilayer simultaneous coating method described in U.S. Pat. Nos. 2,761,418, 3,508,947, and 2,761791 can be used. Further, the coating may be repeated by repeating such coating operation. The number of coatings in this case is not particularly limited, and can be appropriately selected according to the desired thickness of the hole transport layer. Further, the coating may be repeated by repeating such coating operation. The number of coatings in this case is not particularly limited, and can be appropriately selected according to the desired thickness of the hole transport layer. Solvents that can be used include tetrahydrofuran (THF), butylene oxide, chloroform, cyclohexanone, chlorobenzene, acetone, polar solvents such as various alcohols, dimethylformamide (DMF), acetonitrile, dimethoxyethane, dimethyl sulfoxide, hexa An organic solvent such as an aprotic solvent such as methylphosphoric triamide can be used. The said solvent may be used independently or may be used with the form of a 2 or more types of mixture.

  The content of the compound represented by the chemical formula (A) in the hole transport layer or a polymer formed by polymerizing a multimer of the compound is not particularly limited. Considering the hole transport characteristics and the ability to suppress / prevent the disappearance of excitons generated near the interface of the photoelectric conversion layer, it is preferably 50 to 100% by weight, more preferably 90 to It is preferably 100% by weight.

  In order to increase the conductivity of the hole transport layer, the polymer is preferably doped with holes. The hole doping amount at this time is not particularly limited, but is preferably 0.15 to 0.66 (pieces) per compound of the chemical formula (A).

  In the electropolymerization, holes are doped by oxidizing a polymer having a structure derived from the compound represented by the chemical formula (A) by applying an electric field.

For the hole transport layer, for example, N (PhBr) ₃ SbCl ₆ , NOPF ₆ , SbCl ₅ , I ₂ , Br ₂ , HClO ₄ , (n—C ₄ H ₉ ) ₄ ClO ₄ are used as necessary. , Trifluoroacetic acid, 4-dodecylbenzenesulfonic acid, 1-naphthalenesulfonic acid, FeCl ₃ , AuCl ₃ , NOSbF ₆ , AsF ₅ , NOBF ₄ , LiBF ₄ , H ₃ [PMo ₁₂ O ₄₀ ], 7, 7, 8 Various additives such as acceptor doping agents such as, 8-tetracyanoquinodimethane (TCNQ), binder resins that do not easily trap holes, and coating improvers such as leveling agents may be added. The said additive may be used individually or may be used in mixture of 2 or more types.

  The material contained in the hole transport layer preferably has a large band gap so as not to prevent light absorption by the sensitizing dye. Specifically, it preferably has a band cap of 2 eV or more, and more preferably has a band cap of 2.5 eV or more. The hole transport layer preferably has a low ionization potential in order to reduce sensitizing dye holes. Although the value of the ionization potential varies depending on the sensitizing dye to be applied, it is usually preferably 4.5 to 5.5 eV, more preferably 4.7 to 5.3 eV.

  In addition, when the visible light absorptance is low, light loss due to absorption is small and deterioration due to light can be suppressed. Therefore, a preferable hole transport layer preferably has an absorbance of 1.0 or less. Further, when the degree of polymerization of the polymer is increased, the absorbance is slightly increased, and in order to obtain a degree of polymerization having a preferable hole transporting ability, a hole transport layer having a degree of polymerization having an absorbance of 0.2 or more is used as the absorbance. preferable. Therefore, the polymer according to the present invention has an absorbance at 400 to 700 nm (an average value of absorbance in a wavelength region of 400 to 700 nm) (preferably, a wavelength of 430 nm or less is cut) of 0.2 to 1.0. Preferably there is.

In the present specification, the absorbance of the hole transport layer (polymer) is defined using the difference in absorbance of the working electrode before and after electrolytic polymerization. In this case, the absorbance is an average of absorbance in a wavelength region of 400 to 700 nm. Mean value. Absorbance is measured using a spectrophotometer (JASCO V-530). As a working electrode, a titanium oxide thin film having an effective area of 10 × 20 mm ² formed on an FTO conductive glass substrate was adsorbed with a dye, immersed in a solution having the same composition as the electrolytic polymerization solution described above, and the counter electrode was a platinum wire, The reference electrode is Ag / Ag ⁺ (AgNO ₃ 0.01M), the holding voltage is −0.16 V, while irradiating light from the direction of the photoelectric conversion layer (using a xenon lamp, light intensity 22 mW / cm ² , wavelength of 430 nm or less The polymer having the repeating unit of the chemical formula (A) is formed on the working electrode and measured while holding the voltage for 30 minutes. In order to correct the influence of the variation in film thickness, the film thickness of the sample is measured, and a value divided by the film thickness (μm) is used. The film thickness is measured by Dektak 3030 (manufactured by SLOAN TECHNOLOGY Co.).

  The formation method of a positive hole transport layer is not restrict | limited to the said method, A well-known manufacturing method can apply similarly or suitably modified.

[Second electrode]
The 2nd electrode which concerns on this invention should just have electroconductivity, and arbitrary electroconductive materials are used. Even an insulating material can be used if a conductive material layer is provided on the side facing the hole transport layer. The second electrode preferably has good contact with the hole transport layer. The second electrode preferably has a small work function difference from the hole transport layer and is chemically stable. Such a material is not particularly limited, but is a metal thin film such as gold, silver, copper, aluminum, platinum, rhodium, magnesium, indium, carbon, carbon black, a conductive polymer, a conductive metal oxide (indium -Organic conductors such as tin composite oxide, tin oxide doped with fluorine, and the like. The average thickness of the second electrode is not particularly limited, but is preferably 10 to 1000 nm. The surface resistance of the second electrode is not particularly limited, but is preferably low. Specifically, the range of the surface resistance of the second electrode is preferably 80 Ω / □ (square) or less, and more preferably 20 Ω / □ (square) or less. The lower limit of the surface resistance of the second electrode is preferably as low as possible and need not be specified.

  Moreover, you may use what formed the said metal thin film on the glass substrate as a 2nd electrode.

[Other layers]
In addition to the above-described members (each layer), the photoelectric conversion device of the present invention may further include other members (other layers) for improving the photoelectric conversion efficiency and improving the lifetime of the device. Examples of other members include an exciton block layer, a UV absorption layer, a light reflection layer, a wavelength conversion layer, and a smoothing layer. Further, a layer such as a silane coupling agent may be provided in order to make the metal oxide fine particles unevenly distributed in the upper layer more stable. Further, a metal oxide layer may be laminated adjacent to the photoelectric conversion layer of the present invention.

  Moreover, the photoelectric conversion element of this invention may have various optical function layers for the purpose of more efficient light reception of sunlight. Examples of the optical functional layer include a light condensing layer such as an antireflection film and a microlens array, and a light diffusion layer that can scatter light reflected by the cathode and enter the power generation layer again.

  Various known antireflection layers can be provided as the antireflection layer. For example, when the transparent resin film is a biaxially stretched polyethylene terephthalate film, the refractive index of the easy adhesion layer adjacent to the film is 1. It is more preferable to set it to 57 to 1.63 because the interface reflection between the film substrate and the easy adhesion layer can be reduced and the transmittance can be improved. The method for adjusting the refractive index can be carried out by appropriately adjusting the ratio of the oxide sol having a relatively high refractive index such as tin oxide sol or cerium oxide sol and the binder resin. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion.

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

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it is smaller than this, the effect of diffraction is generated and colored.

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

<Solar cell>
The photoelectric conversion element of this invention can be used especially suitably for a solar cell. Therefore, according to another embodiment of the present invention, there is provided a solar cell including the photoelectric conversion element.

  The solar cell of the present invention has the photoelectric conversion element of the present invention. The solar cell of the present invention comprises the photoelectric conversion element of the present invention, and is designed so that optimum design and circuit design are performed for sunlight, and optimum photoelectric conversion is performed when sunlight is used as a light source. Have. When configuring the solar cell of the present invention, it is preferable that the photoelectric conversion layer, the hole transport layer, and the second electrode are housed in a case and sealed, or the whole is resin-sealed.

  When the solar cell of the present invention is irradiated with sunlight or an electromagnetic wave equivalent to sunlight, the dye supported on the dye support is excited by absorbing the irradiated light or electromagnetic wave and excitons (hole / electron pairs). Is generated. Some excitons generated by excitation are separated by charge, and electrons move to the second electrode via the electron transport layer, conductive support and external load, and are supplied to the charge transport material of the hole transport layer. Is done. Some excitons are charge separated at the interface between the electron transport layer and the dye, the electrons move to the electron transport layer, and then move to the second electrode via the conductive support and external load, Supplied to the charge transport material of the hole transport layer. On the other hand, the dye that has moved electrons to the electron transport layer is an oxidant, but is reduced by the supply of electrons from the second electrode via the polymer of the hole transport layer, and the original state. At the same time, the polymer of the hole transport layer is oxidized and returned to a state where it can be reduced again by the electrons supplied from the second electrode. In this way, electrons flow, and a solar cell using the photoelectric conversion element of the present invention can be configured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the scope of the present invention is not limited to these. In the following examples, the operation was performed at room temperature (25 ° C.) unless otherwise specified. Unless otherwise specified, “%” and “part” mean “% by mass” and “part by mass”, respectively.

(Preparation of dye (CH ₃ NH ₃ PbI ₃ ) precursor solution)
24 mL of methylamine (33% by mass ethanol solution) and 10 mL of hydroiodic acid (57% by mass aqueous solution) were dissolved in 100 mL of ethanol and stirred at room temperature (25 ° C.) in a nitrogen atmosphere. Concentration to dryness gave methylammonium iodide (CH ₃ NH ₃ I). Next, this methylammonium iodide (CH ₃ NH ₃ I) and lead iodide (PbI ₂ ) were dissolved in γ-butyrolactone at a molar ratio of 1: 1, and at 60 ° C., 12 The mixture was stirred for a time to prepare a dye (CH ₃ NH ₃ PbI ₃ ) precursor solution.

(Example 1: Production of photoelectric conversion element SC-1)
1. Formation of substrate / first electrode / electron transport layer Fluorine-doped tin oxide (FTO) glass substrate with transparent conductive film having a surface resistance of 9Ω / □ (square) (FTO coating amount: 7 g / m ² substrate, thickness of first electrode) : 0.9 μm, thickness of conductive support: 1.1 mm) was used as the conductive support. TC100 (manufactured by Matsumoto Kosho): titanium diisopropoxy bis (acetylacetonate) was applied to this conductive support as an electron transport layer by a spin coat method. After heating and drying at 80 ° C. for 10 minutes, baking was performed at 450 ° C. for 10 minutes to form a titanium oxide layer (porosity C: 1.0% by volume) having a thickness of 100 nm as an electron transporting layer.

2. Formation of photoelectric conversion layer 20% by mass of polyethylene glycol (weight average molecular weight (Mw) 4000), 20% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (8% by weight in terms of dye), dimethylformamide (DMF) 60 A liquid mixed with mass% was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, the photoelectric conversion layer (thickness: about 0.4 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried to form an electron transport layer. Formed on top.

3. Formation of hole transport layer 0.17 mol / L of 2,2 ′, 7,7′-tetrakis (N, N′-di (4-methoxyphenyl) amine) -9,9′-spiro as an aromatic amine derivative Bifluorene (Spiro-OMeTAD), 0.33 mmol / L N (PhBr) ₃ SbCl ₆ as acceptor doping agent, 15 mmol / L Li [(CF ₃ SO ₂ ) ₂ N] as supporting electrolyte, 50 mmol as organic base A monochlorobenzene: acetonitrile = 19: 1 solution containing / L 4-tert-butylpyridine was prepared, and spin coating was performed on the upper surface of the photoelectric conversion layer at a rotation speed of 1000 rpm to form a hole transport layer having a layer thickness of 10 μm. .

4). Formation of the second electrode On the obtained hole transport layer, gold was deposited by 90 nm by a vacuum deposition method to form a second electrode. Thereby, the photoelectric conversion element was completed.

(Example 2: Production of photoelectric conversion element SC-2)
A photoelectric conversion element SC-2 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

10% by mass of polyethylene glycol (weight average molecular weight (Mw) 4000), 30% by mass of the above dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (12% by weight in terms of dye), and 60% by mass of dimethylformamide (DMF) were mixed. A liquid was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Then, the photoelectric conversion layer (thickness of about 0.3 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried to form an electron transport layer. Formed on top.

(Example 3: Production of photoelectric conversion element SC-3)
A photoelectric conversion element SC-3 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

5% by mass of polyethylene glycol (weight average molecular weight (Mw) 4000), 35% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (14% by weight in terms of dye), and 60% by mass of dimethylformamide (DMF) were mixed. A liquid was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Then, the photoelectric conversion layer (thickness of about 0.3 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried to form an electron transport layer. Formed on top.

(Example 4: Production of photoelectric conversion element SC-4)
A photoelectric conversion element SC-4 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

1% by mass of polyethylene glycol (weight average molecular weight (Mw) 4000), 39% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (16% by weight in terms of dye), and 60% by mass of dimethylformamide (DMF) were mixed. A liquid was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Then, the photoelectric conversion layer (thickness: about 0.2 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried. Formed on top.

(Example 5: Production of photoelectric conversion element SC-5)
A photoelectric conversion element SC-5 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

5% by mass of polyethylene glycol (weight average molecular weight (Mw) 2000), 35% by mass of the above dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (14% by weight in terms of dye), and 60% by mass of dimethylformamide (DMF) were mixed. A liquid was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Then, the photoelectric conversion layer (thickness: about 0.2 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried. Formed on top.

(Example 6: Production of photoelectric conversion element SC-6)
A photoelectric conversion element SC-6 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

5% by mass of polyethylene glycol (weight average molecular weight (Mw) 10,000), 35% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (14% by weight in terms of dye), and 60% by mass of dimethylformamide (DMF) were mixed. A liquid was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, the photoelectric conversion layer (thickness: about 0.4 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried to form an electron transport layer. Formed on top.

(Example 7: Production of photoelectric conversion element SC-7)
A photoelectric conversion element SC-7 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

5% by mass of polyethylene glycol (weight average molecular weight (Mw) 40,000), 35% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (14% by weight in terms of dye), 60% by mass of dimethylformamide (DMF) A mixed solution was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, the photoelectric conversion layer (thickness: about 0.4 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried to form an electron transport layer. Formed on top.

(Example 8: Production of photoelectric conversion element SC-8)
A photoelectric conversion element SC-8 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

5% by mass of polyethylene terephthalate (weight average molecular weight (Mw) 6,000), 35% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (14% by weight in terms of dye), 30% by mass of dimethylformamide (DMF) A solution in which 30% by mass of tetrahydrofuran was mixed was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, the photoelectric conversion layer (thickness: about 0.4 μm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried to form an electron transport layer. Formed on top.

(Example 9: Production of photoelectric conversion element SC-9)
A photoelectric conversion element SC-9 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

5% by mass of polycarbonate (weight average molecular weight (Mw) 21,000) represented by the following chemical formula, 35% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (14% by weight in terms of dye), dimethylformamide (DMF) ) A liquid in which 60% by mass was mixed was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Then, the photoelectric conversion layer (thickness: about 0.8 nm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is left to stand on a hot plate heated to 100 ° C. for 1 hour and dried to form an electron transport layer. Formed on top.

(Example 10: Production of photoelectric conversion element SC-10)
A photoelectric conversion element SC-10 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

5% by mass of nylon 6 (weight average molecular weight (Mw) 100,000), 35% by mass of the dye (CH ₃ NH ₃ PbI ₃ ) precursor solution (14% by weight in terms of dye), 30% by mass of dimethylformamide (DMF), A liquid in which 30% by mass of tetrahydrofuran was mixed was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Then, the photoelectric conversion layer (thickness of about 0.3 nm) containing the dye (CH ₃ NH ₃ PbI ₃ ) and the dye support is dried by leaving it on a hot plate heated to 100 ° C. for 1 hour and drying. Formed on top.

(Example 11: Production of photoelectric conversion element SC-11)
A photoelectric conversion element SC-11 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

A liquid in which 1% by mass of polyethylene glycol (weight average molecular weight (Mw) 4000), 39% by mass of lead iodide (PbI ₂ ), and 60% by mass of dimethylformamide (DMF) was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, it was left on a hot plate heated to 100 ° C. for 1 hour and dried. Next, this was immersed in a 2-propanol solution (concentration: 0.06 mol / L) of methylammonium iodide (CH ₃ NH ₃ I) and then left on a hot plate heated to 80 ° C. for 1 hour to dry. This formed the photoelectric converting layer (thickness about 0.2 nm) containing a pigment | dye support body on the electron carrying layer.

(Example 12: Production of photoelectric conversion element SC12)
A photoelectric conversion element SC-12 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

A liquid in which 7% by mass of polyethylene glycol (weight average molecular weight (Mw) 4000), 33% by mass of lead iodide (PbI ₂ ), and 60% by mass of dimethylformamide (DMF) were prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, it was left on a hot plate heated to 100 ° C. for 1 hour and dried. Next, this was immersed in a 2-propanol solution (concentration: 0.06 mol / L) of methylammonium iodide (CH ₃ NH ₃ I) and then left on a hot plate heated to 80 ° C. for 1 hour to dry. Thus, a photoelectric conversion layer (thickness: about 0.3 nm) including the dye support was formed on the electron transport layer.

(Example 13: Production of photoelectric conversion element SC-13)
A photoelectric conversion element SC-13 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

A liquid in which 15% by mass of polyethylene glycol (weight average molecular weight (Mw) 4000), 25% by mass of lead iodide (PbI ₂ ), and 60% by mass of dimethylformamide (DMF) was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, it was left on a hot plate heated to 100 ° C. for 1 hour and dried. Next, this was immersed in a 2-propanol solution (concentration: 0.06 mol / L) of methylammonium iodide (CH ₃ NH ₃ I) and then left on a hot plate heated to 80 ° C. for 1 hour to dry. This formed the photoelectric converting layer (thickness about 0.4 nm) containing a pigment | dye support body on the electron carrying layer.

(Example 14: Production of photoelectric conversion element SC-14)
A photoelectric conversion element SC-14 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

A liquid in which 7% by mass of polyethylene glycol (weight average molecular weight (Mw) 10,000), 33% by mass of lead iodide (PbI ₂ ), and 60% by mass of dimethylformamide (DMF) was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, it was left on a hot plate heated to 100 ° C. for 1 hour and dried. Next, this was immersed in a 2-propanol solution (concentration: 0.06 mol / L) of methylammonium iodide (CH ₃ NH ₃ I) and then left on a hot plate heated to 80 ° C. for 1 hour to dry. Thus, a photoelectric conversion layer (thickness: about 0.3 nm) including the dye support was formed on the electron transport layer.

(Example 15: Production of photoelectric conversion element SC-15)
A photoelectric conversion element SC-15 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

A liquid in which 7% by mass of polyethylene terephthalate (weight average molecular weight (Mw) 6,000), 33% by mass of lead iodide (PbI ₂ ), 30% by mass of dimethylformamide (DMF), and 30% by mass of tetrahydrofuran was prepared. 100 μL of the mixed solution was dropped onto the electron transport layer, and spin coating was performed at 2000 rpm for 60 seconds. Thereafter, it was left on a hot plate heated to 100 ° C. for 1 hour and dried. Next, this was immersed in a 2-propanol solution (concentration: 0.06 mol / L) of methylammonium iodide (CH ₃ NH ₃ I), and then allowed to stand for 1 hour on a hot plate heated to 80 ° C. and dried. Thus, a photoelectric conversion layer (thickness: about 0.3 nm) including the dye support was formed on the electron transport layer.

(Comparative Example 1: Production of photoelectric conversion element SC-16)
A photoelectric conversion element SC-16 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

100 μL of a solution for diluting ethanol of titanium oxide paste, which is a dispersion of polyethylene glycol (average particle size = 18 nm: PASOL HPW-18NR, manufactured by JGC Catalysts & Chemicals Co., Ltd.) is dropped on the electron transport layer and spinned at 1500 rpm for 30 seconds. Coat film formation was performed. Thereafter, baking was performed at 450 ° C. for 20 minutes to form a 0.4 μm titanium oxide film. A liquid in which 40% by mass (16% by weight in terms of dye) of the above dye (CH ₃ NH ₃ PbI ₃ ) precursor solution and 60% by mass of dimethylformamide (DMF) were mixed was prepared. 40 μL of the mixed solution was dropped onto the titanium oxide film, and spin coating was performed at 1500 rpm for 30 seconds. Thereafter, for 1 hour on a hot plate heated to 100 ° C., by drying, to form a photoelectric conversion layer containing a dye (CH 3 _NH 3 _{PbI 3)} and titanium oxide on the electron transport layer.

(Comparative Example 2: Production of photoelectric conversion element SC-17)
A photoelectric conversion element SC-17 was produced in the same manner as in Example 1 except that “2. Formation of photoelectric conversion layer” in Example 1 was as described below.

A liquid in which 40% by mass (16% by weight in terms of dye) of the above dye (CH ₃ NH ₃ PbI ₃ ) precursor solution and 60% by mass of dimethylformamide (DMF) were mixed was prepared. 100 μL of the mixed solution was dropped on the electron transport layer, and spin coating was performed at 1000 rpm for 30 seconds. Thereafter, for 1 hour on a hot plate heated to 100 ° C., and then dried to dye a photoelectric conversion layer comprising a (CH 3 _NH 3 _{PbI 3)} formed on the electron transport layer.

(Measurement of short circuit current density)
Using a solar simulator (manufactured by Eihiro Seiki Co., Ltd.), the photoelectric conversion elements produced in the above Examples and Comparative Examples were passed through an AM filter (AM-1.5) from a xenon lamp to an intensity of 100 mW / cm. ² simulated sunlight was irradiated. And the current-voltage characteristic at room temperature of the photoelectric conversion element was measured using the IV tester, and the short circuit current density (Jsc) was measured.

  From the above results, in Examples 1 to 15 including a predetermined organic compound as a dye support, the short circuit current density is significantly improved as compared with Comparative Example 1 using a semiconductor as a support and Comparative Example 2 including no support. Was shown to do.

  In addition, Examples 1 to 10 and 12 to 15 in which the content of the dye support is in the range of 5 to 400 parts by mass with respect to 100 parts by mass of the dye exhibit particularly high short-circuit current density. I understood.

1 substrate,
2 first electrode,
3 electron transport layer,
4 dyes,
5 Dye support,
6 photoelectric conversion layer,
7 hole transport layer,
8 Second electrode,
9 Incident direction of sunlight,
10 Photoelectric conversion element.

Claims (4)

In a photoelectric conversion element having a substrate, a first electrode, an electron transport layer, a photoelectric conversion layer containing a dye and a dye support, a hole transport layer, and a second electrode,
The dye is represented by the following formula (1):
However, R ^{1 to} R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted carbon atom having 3 to 6 carbon atoms. Represents a cycloalkyl group, a polyethylene oxide group having 2 to 6 carbon atoms, or a substituted or unsubstituted aromatic ring-containing group having 4 to 10 carbon atoms, wherein R ^{1 to} R ⁴ are simultaneously hydrogen atoms. X ^{1 to} X ³ each independently represent a halogen atom; and M represents a group 14 atom or transition metal of the periodic table.
Including a compound represented by
The said pigment | dye support body is a photoelectric conversion element containing the organic compound which has an oxygen atom, a nitrogen atom, or a sulfur atom and whose weight average molecular weight (Mw) is 500 or more.   The photoelectric conversion device according to claim 1, wherein the organic compound is at least one selected from the group consisting of polyether, polyester, polyamide, polyimide, polycarbonate, and sulfur-containing polyisopropylene (vulcanized rubber).   Content of the said pigment | dye support body is a photoelectric conversion element of Claim 1 or 2 which is 5-400 mass parts with respect to 100 mass parts of content of the said pigment | dye.   The solar cell which has a photoelectric conversion element of any one of Claims 1-3.