JP2014146534A - Dye sensitized solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a complete solid state dye sensitized solar cell in which each electrode can be completely covered with each charge transport material therefor, and thereby no short circuit is caused.SOLUTION: A dye sensitized solar cell includes a first electrode and a second electrode facing the first electrode. An electron transport layer is provided in the first electrode. The electron transport layer is covered with a photosensitizer in which a sensitizing dye portion and a hole transport portion are coupled at a non-conjugated bond portion and/or a co-adsorbent having a hole transport portion and a non-conjugated bond portion. The second electrode is provided on the photosensitizer and/or the co-adsorbent.

Description

  The present invention relates to a dye-sensitized solar cell.

In recent years, the importance of solar cells has been increasing as an alternative energy to fossil fuels and as a countermeasure against global warming. However, current solar cells typified by silicon-based solar cells are expensive at present and are factors that hinder their spread.

Therefore, research and development of various low-cost solar cells are underway, and among them, dye-sensitized solar cells announced by Graetzel et al. Of Lausanne University of Technology in Switzerland are expected to be put into practical use (for example, (See Patent Document 1, Non-Patent Documents 1 and 2).
This solar cell has a structure in which a porous metal oxide semiconductor is provided on a transparent conductive glass substrate, a dye adsorbed on the surface thereof, an electrolyte having a redox pair, and a counter electrode.

The operation principle of this solar cell is as follows. The dye absorbs light and is excited from HOMO to LUMO, injecting electrons into the titanium oxide conductor. The dye that has injected electrons into titanium oxide loses electrons and is oxidized. 2. The electrons injected into the titanium oxide are guided to an external circuit via the transparent conductive film on the glass substrate. 3. The oxidized dye receives electrons from the redox electrolyte. 4). A redox electrolyte receives electrons from a counter electrode and recovers to its original state.

Graetzel et al. Significantly improved the photoelectric conversion efficiency by making a metal oxide semiconductor electrode such as titanium oxide porous to increase the surface area, and by adsorbing a ruthenium complex as a dye on a single molecule basis.

In addition, the dye-sensitized solar cell is expected to be able to reduce the manufacturing cost because a printing method can be applied to the device manufacturing method and an expensive manufacturing facility is not required.
However, this solar cell contains an iodine-based electrolyte and has problems such as a decrease in power generation efficiency due to deterioration of the iodine redox system, and volatilization and leakage of the electrolyte.

In order to compensate for this drawback, the following completely solid dye-sensitized solar cell has been announced.
1) Using an inorganic semiconductor (for example, see Non-Patent Documents 3 and 4)
2) A material using a low molecular weight organic hole transport material (for example, see Patent Document 2, Non-Patent Documents 5 and 6)
3) Using conductive polymer (for example, see Patent Document 3 and Non-Patent Document 7)

  In the solar cell described in Non-Patent Document 3 using the inorganic semiconductor of 1), copper iodide is used as a constituent material of the p-type semiconductor layer. Immediately after the production, the comparatively good photoelectric conversion efficiency is also halved in a few hours due to deterioration due to the increase of crystal grains of copper iodide and the like. Therefore, in the solar cell described in Non-Patent Document 4, the crystallization of copper iodide is suppressed by adding imidazolinium thiocyanate, but this is not sufficient.

  The solid-type solar cell using the organic hole transport material described in Non-Patent Document 5 of 2) has been reported by Hagen et al. And improved by Graetzel et al. (Non-Patent Document 6).

Moreover, the solid-state solar cell using the triphenylamine compound described in Patent Document 2 forms a charge transport layer by vacuum-depositing the triphenylamine compound. Therefore, the triphenylamine compound cannot reach the internal pores of the porous semiconductor, and only low conversion efficiency is obtained.

Furthermore, in the example described in Non-Patent Document 6, a spiro-type hole transport material is dissolved in an organic solvent, and a composite of titania nanoparticles and a hole transport material is obtained using spin coating.
However, the optimum value of the titania nanoparticle thickness in this solar cell is about 2 μm, which is very thin compared with 10 to 20 μm when using an iodine electrolyte. Therefore, the amount of the dye adsorbed on the titanium oxide is small, and it is difficult to perform sufficient light absorption and carrier generation, which does not reach the characteristics when using the electrolytic solution. The reason why the film thickness of the nanotitania particles remains at 2 μm is that the penetration of the hole transport material becomes insufficient as the film thickness increases.

  As a solid-state solar cell of the type 3) using a conductive polymer, Osaka University Yanagida et al. Reported using polypyrrole (see Non-Patent Document 7). Also in these solar cells, the conversion efficiency is low. In addition, the solid-state solar cell using the polythiophene derivative described in Patent Document 3 is provided with a charge transfer layer using an electrolytic polymerization method on a porous titanium oxide electrode on which a dye is adsorbed. There is a problem that the dye is desorbed from titanium oxide or the dye is decomposed.

  When the penetration of the hole transporting material is insufficient, the dye on the electrode is desorbed, the dye is decomposed, etc., and the coating of the current collecting electrode is lost, a short circuit occurs between the electrode and the dye and / or between the electrodes, thus functioning as a solar cell. No longer.

Patent Document 4 discloses that a solid electrolyte layer is provided between the dye and the counter electrode so that the dye on the electrode does not contact the counter electrode.
However, in this dye-sensitized solar cell, it is necessary to fill the space between the electrode on which the dye is adsorbed and the counter electrode with a hole transport material. Especially, a hole transport material such as an organic semiconductor has high resistance, and therefore transports long-distance holes. It is difficult.

  An object of the present invention is to provide a fully solid-state dye-sensitized solar cell in which each electrode can be completely covered with each charge transport material for them, without short-circuiting, and with a short hole transport distance. And

As a result of intensive studies by the present inventors, a photosensitizer and / or a co-adsorbent bonded to a hole transporting site and a non-conjugated binding site, and a non-conjugated binding site adsorbed on the electrode side, a bulky hole. Occurs when the transportable part faces the second electrode, and the adjacent photosensitizer and co-adsorbent can completely cover each electrode without interfering with each other. It has been found that short circuiting can be prevented and the hole transport distance can be shortened, and the present invention has been completed.
That is, the said subject is solved by following (1)-(11) of this invention.
(1) A dye-sensitized solar cell having a first electrode and a second electrode facing the first electrode,
The first electrode is provided with an electron transporting layer, and the electron transporting layer is a photosensitizer in which a sensitizing dye site and a hole transporting site are bonded at a non-conjugated binding site, and / or a hole transporting site and a non-transporting site. A dye-sensitized solar, which is coated with a co-adsorbent having a conjugated binding site, and wherein the second electrode is provided on the photosensitizer and / or the co-adsorbent. battery.
(2) The item (1), wherein the non-conjugated bond site of the photosensitizer and coadsorbent is a divalent linking group containing an alkylene group and / or an ether group and not covalently bonded. Dye-sensitized solar cell described in "
(3) “The photosensitizer is a photosensitizer represented by the following general formula (1), and the coadsorbent is a coadsorbent represented by the following general formula (2): The dye-sensitized solar cell according to item (1) or (2), characterized in that:

（式中、Ｘは窒素原子を含むホール輸送性構造を表し、Ｒ１、Ｒ２はアルキル基、アリール基、Ｎ原子と共にヘテロ環またはヘテロ環残基を構成するに必要な部位Ａ１を表し、Ｒ３は２価の連結基、Ａｒ１は２価のアリーレン、Ｒ４はアルキレン基及び／またはエーテル基を含む共有結合しない２価の連結基を表す。Ｙは酸性基を表す。）

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R 1 and R 2 represent a site A 1 necessary for constituting a heterocyclic ring or a heterocyclic residue together with an alkyl group, an aryl group, and an N atom, and R 3 represents A divalent linking group, Ar1 represents a divalent arylene, R4 represents a divalent linking group containing no alkylene group and / or an ether group, and Y represents an acidic group.

（式中、Ｘは窒素原子を含むホール輸送性構造を表し、Ｒ４はアルキレン基及び／またはエーテル基を含む共有結合しない２価の連結基を表す。Ｙは酸性基を表す。）」、
（４）「前記一般式（１）で表される光増感剤が、下記一般式（３）で表される光増感剤であることを特徴とする前記第（３）項に記載の色素増感型太陽電池；

(Wherein X represents a hole transporting structure containing a nitrogen atom, R4 represents a divalent linking group containing no alkylene group and / or an ether group and not covalently bonded. Y represents an acidic group).
(4) “The photosensitizer represented by the general formula (1) is a photosensitizer represented by the following general formula (3),” Dye-sensitized solar cell;

（式中、Ｘは窒素原子を含むホール輸送性構造を表し、Ｒ３は２価の連結基、Ｒ４はアルキレン基及び／またはエーテル基を含む共有結合しない２価の連結基を表す。Ｙは酸性基を表す。Ａｒ１は２価のアリーレン、Ｒ５、Ｒ６は水素原子、アルキル基、アリール基を表し、Ｒ５とＲ６で環状構造を形成してもよい。）」、
（５）「前記一般式（１）乃至（３）の窒素原子を含むホール輸送性構造Ｘが、下記一般式（４）で表される構造であることを特徴とする前記第（３）項または第（４）項に記載の色素増感型太陽電池；

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R3 represents a divalent linking group, R4 represents a divalent linking group containing an alkylene group and / or an ether group and not a covalent bond. Y is acidic. Ar1 represents a divalent arylene, R5 and R6 each represents a hydrogen atom, an alkyl group, or an aryl group, and R5 and R6 may form a cyclic structure.
(5) The item (3), wherein the hole transport structure X containing a nitrogen atom of the general formulas (1) to (3) is a structure represented by the following general formula (4): Or the dye-sensitized solar cell according to item (4);

（式中、Ｒ７、Ｒ８はアルキル基、アルケニル基、アリール基、Ｎ原子と共にヘテロ環またはヘテロ環残基を構成するに必要な部位を表し、Ｒ９は２価のアルキレン、２価のアリーレン、２価のヘテロ環を表す。Ｒ７とＲ８、Ｒ８とＲ９、Ｒ７とＲ９は、これらそれぞれの残基が直接または２価の炭化水素を介して間接的に結合し、環状構造を形成してもよい。）」、
（６）「前記一般式（３）で表される光増感剤が、下記一般式（５）で表される光増感剤であることを特徴とする前記第（４）項または第（５）項に記載の色素増感型太陽電池；

(Wherein R7 and R8 represent an alkyl group, an alkenyl group, an aryl group, a site necessary for forming a heterocyclic ring or a heterocyclic residue together with an N atom, R9 represents a divalent alkylene, a divalent arylene, 2 R7 and R8, R8 and R9, and R7 and R9 may be bonded to each other directly or indirectly through a divalent hydrocarbon to form a cyclic structure. .) ",
(6) “The photosensitizer represented by the general formula (3) is a photosensitizer represented by the following general formula (5): The dye-sensitized solar cell according to 5);

（式中、Ｒ５、Ｒ６は水素原子、アルキル基、アリール基を表し、Ｒ７、Ｒ８はアルキル基、アルケニル基、アリール基、Ｎ原子と共にヘテロ環またはヘテロ環残基を構成するに必要な部位を表し、Ｒ９は２価のアルキレン、２価のアリーレン、２価のヘテロ環を表す。Ｒ７とＲ８、Ｒ８とＲ９、Ｒ７とＲ９は、これらそれぞれの残基が直接または２価の炭化水素を介して間接的に結合し、環状構造を形成してもよい。Ｒ１０、Ｒ１１は酸素原子、硫黄原子を表し、Ｒ１２は酸素原子、硫黄原子、ジシアノメチレン基、ローダニン環を表す。Ｒ１３は２価のアルキレン、２価のアリーレンを表す。Ａｒ１は２価のアリーレン、ｎは２〜１８の整数を表す。）」、
（７）「前記一般式（２）で表される共吸着剤が、下記一般式（６）で表される共吸着剤であることを特徴とする前記第（３）項乃至第（６）項のいずれかに記載の色素増感型太陽電池；

(In the formula, R5 and R6 represent a hydrogen atom, an alkyl group, and an aryl group, and R7 and R8 represent a site necessary for constituting a heterocyclic ring or a heterocyclic residue together with an alkyl group, an alkenyl group, an aryl group, and an N atom. R9 represents a divalent alkylene, a divalent arylene, a divalent heterocycle, and R7 and R8, R8 and R9, and R7 and R9 are each directly or via a divalent hydrocarbon. R10 and R11 each represents an oxygen atom or a sulfur atom, R12 represents an oxygen atom, a sulfur atom, a dicyanomethylene group, or a rhodanine ring, and R13 represents a divalent ring. Alkylene represents a divalent arylene, Ar1 represents a divalent arylene, and n represents an integer of 2 to 18.) "
(7) The co-adsorbent represented by the general formula (2) is a co-adsorbent represented by the following general formula (6): (3) to (6) The dye-sensitized solar cell according to any one of the items;

（式中、Ｒ７、Ｒ８はアルキル基、アルケニル基、アリール基、Ｎ原子と共にヘテロ環またはヘテロ環残基を構成するに必要な部位を表し、Ｒ９は２価のアルキレン、２価のアリーレン、２価のヘテロ環を表す。Ｒ７とＲ８、Ｒ８とＲ９、Ｒ７とＲ９は、これらそれぞれの残基が直接または２価の炭化水素を介して間接的に結合し、環状構造を形成してもよい。Ｒ１４は２価のアルキレン、アリーレンを表す。ｎは２〜１８の整数、ｍは０、１を表す。）」、
（８）「前記電子輸送層は、ナノ粒子からなるｎ型酸化物半導体で形成されたものあることを特徴とする前記第（１）項乃至第（７）項のいずれかに記載の色素増感型太陽電池」、
（９）「前記酸化物半導体が、酸化チタン、酸化亜鉛、酸化スズ、酸化ニオブの少なくとも１種以上から選ばれたものであることを特徴とする前記第（８）項に記載の色素増感型太陽電池」、
（１０）「前記第二電極が有機導電体を含有するものであり、該有機導電体が、下記一般式（７）で表されるドナー性化合物と下記一般式（８）で表されるアクセプター性化合物を含有することを特徴とする前記第（１）項乃至第（９）項のいずれかに記載の色素増感型太陽電池；

(Wherein R7 and R8 represent an alkyl group, an alkenyl group, an aryl group, a site necessary for forming a heterocyclic ring or a heterocyclic residue together with an N atom, R9 represents a divalent alkylene, a divalent arylene, 2 R7 and R8, R8 and R9, and R7 and R9 may be bonded to each other directly or indirectly through a divalent hydrocarbon to form a cyclic structure. R14 represents divalent alkylene or arylene, n represents an integer of 2 to 18, m represents 0 or 1) ",
(8) The dye enhancement according to any one of (1) to (7), wherein the electron transport layer is formed of an n-type oxide semiconductor made of nanoparticles. Sensitive solar cell ",
(9) “The dye sensitization according to item (8), wherein the oxide semiconductor is selected from at least one of titanium oxide, zinc oxide, tin oxide, and niobium oxide.” Type solar cell ",
(10) “The second electrode contains an organic conductor, and the organic conductor is a donor compound represented by the following general formula (7) and an acceptor represented by the following general formula (8). A dye-sensitized solar cell according to any one of Items (1) to (9), which further comprises an organic compound;

（式中、Ａｒ２、Ａｒ３は酸素原子、硫黄原子、セレン、またはテルルを含むヘテロ環を表す。）

(In the formula, Ar 2 and Ar 3 represent a heterocycle containing an oxygen atom, a sulfur atom, selenium, or tellurium.)

（式中、Ａｒ４は２価のアリーレン、Ｏ、Ｓ、Ｓｅ、またはＮを含むヘテロ環を表し、Ｒ１５、Ｒ１６、Ｒ１７、Ｒ１８は電子吸引性基を表す。）」、
（１１）「前記一般式（７）で表されるドナー性化合物が、下記一般式（９）で表されるドナー性化合物であり、一般式（８）で表されるアクセプター性化合物が下記一般式（１０）で表されるアクセプター性化合物あることを特徴とする前記第（１０）項に記載の色素増感型太陽電池；

(Wherein Ar 4 represents a divalent arylene, O, S, Se, or a heterocyclic ring containing N, and R 15, R 16, R 17 and R 18 represent an electron-withdrawing group) ”
(11) “The donor compound represented by the general formula (7) is a donor compound represented by the following general formula (9), and the acceptor compound represented by the general formula (8) is the following general compound. The dye-sensitized solar cell according to item (10), which is an acceptor compound represented by formula (10);

（式中、Ｒ１５〜Ｒ１８は酸素原子、硫黄原子、セレン原子を表す。）

(In the formula, R15 to R18 represent an oxygen atom, a sulfur atom, and a selenium atom.)

（式中、Ａｒ４は２価のアリーレン、ヘテロ環を表す。）」。

(In the formula, Ar 4 represents a divalent arylene or heterocyclic ring).

As will be understood from the following detailed and specific description, the present invention provides a dye-sensitized solar cell that has a very short hole transport distance and exhibits photoelectric conversion without short-circuiting.

It is an example of sectional drawing showing the structure of the dye-sensitized solar cell which concerns on this invention. It is an example of sectional drawing showing the structure of the dye-sensitized solar cell which concerns on this invention. It is an example of the schematic diagram showing the electron carrying layer surface concerning this invention. It is an example of the schematic diagram showing the electron carrying layer surface concerning this invention. It is IR spectrum of exemplary compound A-22. It is IR spectrum of exemplary compound A-07. 4 is an IR spectrum of Exemplified Compound A-23. 4 is an IR spectrum of Exemplified Compound A-24. 4 is an IR spectrum of Exemplified Compound B-09.

The dye-sensitized solar cell of the present invention will be described in detail.
FIG.1 and FIG.2 is sectional drawing which shows an example of the dye-sensitized solar cell of this invention.
As shown in FIG. 1, a first electrode 2 and a second electrode 8 facing the first electrode 2 are provided on a substrate 1. The first electrode is provided with an electron transport layer 3 including a dense electron transport layer 4 and a porous electron transport layer 5, and a photosensitizer 6 is adsorbed on the electron transport layer 3, and the photosensitization is performed. The second electrode 8 is formed on the agent 6.

  In the dye-sensitized solar cell of the present invention, as shown in FIG. 2, the photosensitizer 6 and the co-adsorbent 7 may be adsorbed on the electron transport layer 3. The second electrode 8 may contain an organic conductive agent.

FIG. 3 schematically shows the surface state of the electron transport layer of the dye-sensitized solar cell of the present invention. The photosensitizer is adsorbed on the surface of the electron transport layer by the acidic group Y. Optical sensitizer and a sensitizing dye moiety and hole transporting moiety (HTM) has a structure bound by a non-conjugated binding site (R _4), wherein the non-conjugated binding site (R ₄₎ is free to rotate By being a divalent linking group that does not have a covalent bond including a C—C bond or a C—O bond, the hole transporting structure site can move freely, and even if it has a bulky structure, adjacent photosensitization The surface of the electron transport layer can be completely covered without interfering agents, and a short circuit between the electrode and the dye and / or between the electrodes can be prevented.
Furthermore, since the dye has a hole transporting site bound to only one molecule, the transport distance is very short, and the counter electrode with low resistance is used for hole transport while preventing contact between the counter electrode and the dye. it can.

FIG. 4 schematically shows the surface state of another electron transport layer of the dye-sensitized solar cell of the present invention. A photosensitizer and a coadsorbent are adsorbed on the surface of the electron transport layer by the acidic group Y.
The non-conjugated bonding site (R ₄ ) of the co-adsorbent is a divalent linking group that does not covalently include a freely rotatable C—C bond or C—O bond, so that adjacent co-adsorbents are Without interfering, the non-conjugated bonding site of the co-adsorbent having a hole transporting site and a non-conjugated bonding site can be adsorbed to the electron transport layer through the acidic group from the gap between the photosensitizers, and the bulky hole Since the transport site fills the gap between the photosensitizers, the surface of the electron transport layer is completely covered, and a short circuit between the electrode and the dye and / or between the electrodes can be prevented.
Furthermore, since the co-adsorbent has only one molecule of the hole transporting site bonded thereto, the transport distance is very short, and the counter electrode has a low resistance with respect to hole transport while preventing contact between the counter electrode and the dye. Can be used.

<First electrode>
The first electrode of the present invention is an electron current collecting electrode, and the electron current collecting electrode is not particularly limited as long as it is a conductive material transparent to visible light. Known electrodes used for liquid crystal panels and the like can be used. For example, indium / tin oxide (hereinafter referred to as ITO), fluorine-doped tin oxide (hereinafter referred to as FTO), antimony-doped tin oxide (hereinafter referred to as ATO), indium / zinc oxide, niobium / titanium oxide , Graphene and the like, and these may be used alone or in a plurality of layers.
The thickness of the electron collector electrode is preferably 5 nm to 100 μm, more preferably 50 nm to 10 μm.

  The electron collecting electrode is preferably provided on a substrate made of a material transparent to visible light in order to maintain a certain hardness. Examples of the substrate include glass, a transparent plastic plate, a transparent plastic film, and an inorganic transparent crystal. The body is used.

Moreover, you may use the conventionally well-known transparent electrode with which an electronic current collection electrode and a board | substrate are integrated, As this transparent electrode, for example, FTO coat glass, ITO coat glass, zinc oxide: aluminum coat glass, FTO coat Examples thereof include a transparent plastic film and an ITO-coated transparent plastic film.
In addition, a transparent electrode obtained by doping cations or anions with different valences into tin oxide or indium oxide, or a metal electrode having a structure capable of transmitting light, such as a mesh shape or a stripe shape, provided on a substrate such as a glass substrate Good. These may be used alone or in combination of two or more kinds.

  Moreover, you may provide a metal lead wire in the adhesive surface with a board | substrate for the purpose of reducing resistance at the 1st electrode. Examples of the material of the metal lead wire include metals such as aluminum, copper, silver, gold, platinum, and nickel. The metal lead wire for decreasing the resistance may be installed on the substrate by vapor deposition, sputtering, pressure bonding, or the like, and the ITO or FTO may be provided thereon.

<Electron transport layer>
The dye-sensitized solar cell of the present invention has an electron transport layer 3 made of a semiconductor as the electron transport layer 3 on the first electrode.
The electron transport layer 3 preferably has a laminated structure having a dense electron transport layer 4 on the first electrode and further having a porous electron transport layer 5 thereon.

The dense electron transport layer 4 is formed for the purpose of improving contact efficiency with the first electrode 2 and improving conversion efficiency.
In the present invention, the “dense” of the dense electron transport layer means that the inorganic oxide semiconductor is filled at a density higher than the packing density of the semiconductor fine particles in the porous electron transport layer 5.

  The thickness of the dense electron transport layer 4 is not particularly limited, but is preferably 10 nm to 1 μm, and more preferably 20 nm to 700 nm.

The porous electron transport layer 5 is formed on the dense electron transport layer 4 in order to increase the amount of dye to be adsorbed by increasing the specific surface area and improve the conversion efficiency. It may be a single layer or a multilayer. Multi-layer coating is an effective means when the film thickness is insufficient with a single coating.
When the porous electron transport layer has a multi-layer structure, it is possible to apply a multi-layer coating of a dispersion of semiconductor fine particles having different particle sizes, or to apply a multi-layer coating of different types of semiconductors, resins, and additives. You can also.

  In general, as the film thickness of the electron transport layer increases, the amount of the photosensitized compound carried per unit projected area increases, so that the light capture rate increases. Loss due to coupling also increases. Therefore, the film thickness of the electron transport layer is preferably 100 nm to 100 μm.

  The semiconductor constituting the electron transport layer is not particularly limited, and a known semiconductor can be used. Specifically, a single semiconductor such as silicon or germanium, a compound semiconductor typified by a metal chalcogenide, a compound having a perovskite structure, or the like can be given.

Examples of the metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony, Bismuth sulfide, cadmium, lead selenide, cadmium telluride and the like.
Other compound semiconductors are preferably phosphides such as zinc, gallium, indium, cadmium, gallium arsenide, copper-indium-selenide, copper-indium-sulfide, and the like.

As the compound having a perovskite structure, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate and the like are preferable.
Among these, an n-type oxide semiconductor is preferable, and titanium oxide, zinc oxide, tin oxide, and niobium oxide are particularly preferable, and they may be used alone or in combination of two or more. The crystal type of these semiconductors is not particularly limited, and may be single crystal, polycrystal, or amorphous.

Although there is no restriction | limiting in particular as a size of the semiconductor fine particle which forms a porous electron carrying layer, 1-100 nm is preferable and, as for the average particle diameter of a primary particle, 5-50 nm is more preferable.
Further, it is possible to improve efficiency by mixing or laminating semiconductor fine particles having a large average particle diameter on semiconductor fine particles having a small average particle diameter and scattering incident light. The average particle size of the semiconductor fine particles having a large average particle size is preferably 50 to 500 nm.

There is no restriction | limiting in particular in the preparation methods of an electron carrying layer, The method of forming a thin film in vacuum, such as sputtering, and the wet film forming method are mentioned.
In view of the manufacturing cost and the like, a wet film forming method is particularly preferable, and a method in which a paste in which semiconductor fine particle powder or sol is dispersed is prepared and applied onto an electron collecting electrode substrate is preferable.
When this wet film-forming method is used, the coating method is not particularly limited, and can be performed according to a known method.
For example, dip method, spray method, wire bar method, spin coating method, roller coating method, blade coating method, gravure coating method, and wet printing methods such as relief printing, offset, gravure, intaglio printing, rubber printing, screen printing, etc. Can be used.

When the fine particle powder or sol dispersion used in the wet film-forming method is prepared by mechanical pulverization or milling, at least the fine semiconductor particles or a mixture of fine semiconductor particles and resin is dispersed in water or an organic solvent. Formed.
As the resin used at this time, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid ester, methacrylic acid ester, silicon resin, phenoxy resin, polysulfone resin, polyvinyl butyral resin, polyvinyl formal resin, Examples include polyester resin, cellulose ester resin, cellulose ether resin, urethane resin, phenol resin, epoxy resin, polycarbonate resin, polyarylate resin, polyamide resin, polyimide resin, and the like.

  Solvents for dispersing the semiconductor fine particles include water, alcohol solvents such as methanol, ethanol, isopropyl alcohol, and α-terpineol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ethyl formate, ethyl acetate, and n acetate. Ester solvents such as butyl, ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, or N-methyl-2-pyrrolidone Amide solvents, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromo Halogenated hydrocarbon solvents such as benzene, iodobenzene or 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o Examples thereof include hydrocarbon solvents such as xylene, m-xylene, p-xylene, ethylbenzene, and cumene. These can be used alone or as a mixed solvent of two or more.

In order to prevent re-aggregation of particles, a paste of semiconductor fine particles obtained by a dispersion of semiconductor fine particles or a sol-gel method is used, such as acids such as hydrochloric acid, nitric acid, acetic acid, polyoxyethylene (10) octylphenyl ether, etc. Surfactants, chelating agents such as acetylacetone, 2-aminoethanol, and ethylenediamine can be added.
It is also an effective means to add a thickener for the purpose of improving the film forming property.
Examples of the thickener added at this time include polymers such as polyethylene glycol and polyvinyl alcohol, and thickeners such as ethyl cellulose.

  The semiconductor fine particles are preferably subjected to firing, microwave irradiation, electron beam irradiation, or laser beam irradiation in order to bring the particles into electronic contact with each other after coating and to improve film strength and adhesion to the substrate. . These processes may be performed alone or in combination of two or more.

When firing, the range of the firing temperature is not particularly limited, but if the temperature is raised too much, the resistance of the substrate may be increased or the substrate may be melted, so 30 to 700 ° C is preferable, and 100 to 600 ° C is more preferable. Moreover, although there is no restriction | limiting in particular also in baking time, 10 minutes-10 hours are preferable.
For the purpose of increasing the surface area of the semiconductor fine particles after firing and increasing the efficiency of electron injection from the photosensitizing compound to the semiconductor fine particles, for example, chemical plating using titanium tetrachloride aqueous solution or mixed solution with organic solvent, titanium trichloride Electrochemical plating using an aqueous solution may be performed.

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

A film in which semiconductor fine particles having a diameter of several tens of nanometers are stacked by sintering or the like forms a porous state. This nanoporous structure has a very high surface area, which can be expressed using a roughness factor.
The roughness factor is a numerical value representing the actual area inside the porous body relative to the area of the semiconductor fine particles applied to the substrate. Accordingly, the roughness factor is preferably as large as possible, but is also related to the film thickness of the electron transport layer, and is preferably 20 or more in the present invention.

<Photosensitizer / Co-adsorbent>
In the present invention, in order to further improve the conversion efficiency, a photosensitizer is adsorbed on the surface of the electron transporting semiconductor of the electron transporting layer. The surface of the electron transport layer in the present invention is coated with the following three kinds of combinations of materials.
(1) A photosensitizer in which a sensitizing dye moiety and a hole transporting moiety are bonded at a non-conjugated binding site alone or in combination with the photosensitizer and a known co-adsorbent. (2) A sensitizing dye moiety and hole transport. (3) A known photosensitizer, a hole transporting site and a non-photosensitive agent having a non-conjugated binding site and a coadsorbent having a hole transporting site and a nonconjugated binding site. Combination with a co-adsorbent having a conjugated binding site

First, the photosensitizer will be described. The photosensitizer of the present invention is obtained by binding a sensitizing dye site and a hole transporting site at a non-conjugated binding site.
The hole transporting site only needs to have a hole transporting structure containing a nitrogen atom, and specific examples thereof include methylphenylamine and triphenylamine.
The non-conjugated bond site may be a divalent linking group that is not a conjugated bond but can rotate freely. Specifically, an alkylene, an oxygen atom, a sulfur atom, 1,2-dioxyethylene, 1, Examples thereof include a divalent linking group such as 6-dioxyhexylene that does not have a conjugated bond.
The sensitizing dye moiety has an acidic group that is adsorbed to the electron transport layer, and specific examples thereof include carboxylic acid, sulfonic acid, phosphonic acid, boronic acid, and phenols.
Specific examples of the acidic group are shown below.

  As such a photosensitizer, a photosensitizer represented by the following general formula (1) can be preferably used, and a photosensitizer represented by the general formula (3) is more preferable. A photosensitizer represented by the formula (5) is more preferable.

（式中、Ｘは窒素原子を含むホール輸送性構造を表し、Ｒ１、Ｒ２はアルキル基、アリール基、Ｎ原子と共にヘテロ環またはヘテロ環残基を構成するに必要な部位Ａ１を表し、Ｒ３は２価の連結基、Ａｒ１は２価のアリーレン、Ｒ４はアルキレン基及び／またはエーテル基を含む共有結合しない２価の連結基を表す。Ｙは酸性基を表す。）

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R 1 and R 2 represent a site A 1 necessary for constituting a heterocyclic ring or a heterocyclic residue together with an alkyl group, an aryl group, and an N atom, and R 3 represents A divalent linking group, Ar1 represents a divalent arylene, R4 represents a divalent linking group containing no alkylene group and / or an ether group, and Y represents an acidic group.

In the general formula (1), specific examples of X include methylphenylamine and triphenylamine as described above.
Specific examples of R1 and R2 include alkyl groups such as methyl group, ethyl group and isopropyl group, aryl groups such as phenyl group, 1-naphthyl group and 4-tolyl group, 2-furyl group and 2-thienyl group. A heterocyclic ring can be mentioned, and R1 and R2 may be bonded to form a cyclic structure. Examples of the cyclic structure include a carbazole ring, an indole ring, and an indoline ring.
R3 is a divalent linking group, and is a divalent alkylene such as methylene, 1,2-ethylene, 1,1-ethylene, 1,2-vinylene, 1,2-phenylene, 1,4-phenylene, 2 , 6-naphthylene and the like.

（式中、Ｘは窒素原子を含むホール輸送性構造を表し、Ｒ３は２価の連結基、Ｒ４はアルキレン基及び／またはエーテル基を含む共有結合しない２価の連結基を表す。Ｙは酸性基を表す。Ｒ５、Ｒ６は水素原子、アルキル基、アリール基を表し、Ｒ５とＲ６で環状構造を形成してもよい。）

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R3 represents a divalent linking group, R4 represents a divalent linking group containing an alkylene group and / or an ether group and not a covalent bond. Y is acidic. R5 and R6 each represents a hydrogen atom, an alkyl group or an aryl group, and R5 and R6 may form a cyclic structure.)

（式中、Ｒ５、Ｒ６は水素原子、アルキル基、アリール基を表し、Ｒ７、Ｒ８はアルキル基、アルケニル基、アリール基、Ｎ原子と共にヘテロ環またはヘテロ環残基を構成するに必要な部位を表し、Ｒ９は２価のアルキレン、２価のアリーレン、２価のヘテロ環を表す。Ｒ７とＲ８、Ｒ８とＲ９、Ｒ７とＲ９は、これらそれぞれの残基が直接または２価の炭化水素を介して間接的に結合し、環状構造を形成してもよい。Ｒ１０、Ｒ１１は酸素原子、硫黄原子を表し、Ｒ１２は酸素原子、硫黄原子、ジシアノメチレン基、ローダニン環を表す。Ｒ１３は２価のアルキレン、２価のアリーレンを表す。ｎは２〜１８の整数を表す。）

(In the formula, R5 and R6 represent a hydrogen atom, an alkyl group, and an aryl group, and R7 and R8 represent a site necessary for constituting a heterocyclic ring or a heterocyclic residue together with an alkyl group, an alkenyl group, an aryl group, and an N atom. R9 represents a divalent alkylene, a divalent arylene, a divalent heterocycle, and R7 and R8, R8 and R9, and R7 and R9 are each directly or via a divalent hydrocarbon. R10 and R11 each represents an oxygen atom or a sulfur atom, R12 represents an oxygen atom, a sulfur atom, a dicyanomethylene group, or a rhodanine ring, and R13 represents a divalent ring. Alkylene represents a divalent arylene, and n represents an integer of 2 to 18.)

  Although the specific example of the photosensitizer of this invention is shown below, it is not limited to these at all.

The co-adsorbent suppresses aggregation of the photosensitizer, and the co-adsorbent may be one having a hole transporting site and a non-conjugated binding site. The structure of the hole transporting site can be the same as the hole transporting site of the above photosensitizer, and the non-conjugated binding site depends on the photosensitizer used together, but when adsorbed to the electron transport layer It is preferable that the carbon atom, oxygen atom, and / or sulfur atom has a linear structure having 5 or more so that the photosensitizer is exposed to the outside.
As the coadsorbent, a coadsorbent represented by the following general formula (2) is preferable, and a coadsorbent represented by the general formula (6) is more preferable.

（式中、Ｘは窒素原子を含むホール輸送性構造を表し、Ｒ４はアルキレン基及び／またはエーテル基を含む共有結合しない２価の連結基を表す。Ｙは酸性基を表す。）

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R4 represents a divalent linking group containing an alkylene group and / or an ether group and not covalently bonded. Y represents an acidic group.)

式中、Ｒ７、Ｒ８はアルキル基、アルケニル基、アリール基、Ｎ原子と共にヘテロ環またはヘテロ環残基を構成するに必要な部位を表し、Ｒ９は２価のアルキレン、２価のアリーレン、２価のヘテロ環を表す。Ｒ７とＲ８、Ｒ８とＲ９、Ｒ７とＲ９は、これらそれぞれの残基が直接または２価の炭化水素を介して間接的に結合し、環状構造を形成してもよい。Ｒ１４は２価のアルキレン、アリーレンを表す。ｎは２〜１８の整数、ｍは０、１を表す。）

In the formula, R7 and R8 represent an alkyl group, an alkenyl group, an aryl group, and a site necessary for constituting a heterocyclic ring or a heterocyclic residue together with an N atom, and R9 represents a divalent alkylene, a divalent arylene, a divalent group. Represents a heterocyclic ring. R7 and R8, R8 and R9, and R7 and R9 may be bonded to each other directly or indirectly via a divalent hydrocarbon to form a cyclic structure. R14 represents a divalent alkylene or arylene. n represents an integer of 2 to 18, and m represents 0 or 1. )

Specific examples of such coadsorbents are shown below, but are not limited thereto.

The photosensitizer used in combination with the co-adsorbent of the present invention is not particularly limited as long as it is photoexcited by excitation light, and specifically includes the following compounds.
The metal complex compounds described in JP 7-500630 A, JP 10-233238 A, JP 2000-26487 A, JP 2000-323191 A, JP 2001-59062 A, etc. 10-93118, JP-A No. 2002-164089, JP-A No. 2004-95450, J. Phys. Chem. C, 7224, Vol. 111 (2007), and the like. No. 95450, Chem. Commun., 4887 (2007), etc., JP 2003-264010 A, JP 2004-63274 A, JP 2004-115636 A, JP 2004-200068 A. J. Am. Chem. Soc., 12218, Vol. 126 (2004), Chem. Commun., 3036 (2003), Angew. Chem. Int. Ed., 1923, Vol. 47 (2008) etc. Compounds, J. Am. Chem. Soc., 16701, Vol. 128 (2006), thiophene compounds described in J. Am. Chem. Soc., 14256, Vol. 128 (2006), etc., JP-A-11-86916 Cyanine dyes described in JP-A-11-214730, JP-A-2000-106224, JP-A-2001-76773, JP-A-2003-7359, etc., JP-A-11-214731, Merocyanine dyes described in Kaihei 11-238905, JP-A-2001-52766, JP-A-2001-76775, JP-A-2003-7360, etc., JP-A-10-92477, JP-A-11-273754 , 9-arylxanthene compounds described in JP-A-11-273755, JP-A-2003-3273, etc., JP-A-10-93118, JP-A-2003-31273, etc. The described triarylmethane compounds, JP-A-9-199744, JP-A-10-233238, JP-A-11-204821, JP-A-11-265738, J. Phys. Chem., 2342, Vol.91 (1987), J. Phys. Chem. B, 6272, Vol. 97 (1993), Electroanal. Chem., 31, Vol. 537 (2002), JP 2006-032260, J. Porphyrins Phthalocyanines, 230, Examples include phthalocyanine compounds and porphyrin compounds described in Vol. 3 (1999), Angew. Chem. Int. Ed., 373, Vol. 46 (2007), Langmuir, 5436, Vol. 24 (2008), etc. .
Among these, it is particularly preferable to use metal complex compounds, coumarin compounds, polyene compounds, indoline compounds, and thiophene compounds.

As a method for adsorbing a photosensitizer and a coadsorbent on the porous electron transport layer 5, an electron containing semiconductor fine particles in a solution or dispersion of the photosensitizer and / or coadsorbent is used. A method of immersing the current collecting electrode, or a method of applying the solution or dispersion to the electron transport layer and adsorbing it can be used.
In the former case, dipping method, dipping method, roller method, air knife method, etc. can be used, and in the latter case, wire bar method, slide hopper method, extrusion method, curtain method, spin method, spray method, etc. Can be used.
Further, it may be adsorbed in a supercritical fluid using carbon dioxide or the like.

When adsorbing the photosensitizing compound and / or the coadsorbent, a condensing agent may be used in combination.
The condensing agent has a catalytic action that seems to physically or chemically bond the photosensitizing compound and the electron transport compound to the inorganic surface, or acts stoichiometrically to favorably shift the chemical equilibrium. Either may be sufficient.
Furthermore, a thiol or a hydroxy compound may be added as a condensation aid.

  Solvents that dissolve or disperse the photosensitizing compound and / or co-adsorbent are water, alcohol solvents such as methanol, ethanol, and isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and ethyl formate. Ester solvents such as ethyl acetate or n-butyl acetate, ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, or N- Amide solvents such as methyl-2-pyrrolidone, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluoro Halogenated hydrocarbon solvents such as benzene, bromobenzene, iodobenzene, or 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, Examples thereof include hydrocarbon solvents such as toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, and cumene, and these can be used alone or as a mixture of two or more.

  0.01-500 mass parts is preferable with respect to 1 mass part of photosensitizing compounds, and, as for the addition amount of the coadsorbent of this invention, 0.1-100 mass parts is more preferable.

  The temperature at the time of adsorbing the photosensitizer and / or coadsorbent is preferably −50 ° C. or higher and 200 ° C. or lower.

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

<Second electrode>
The second electrode of the present invention is a hole current collecting electrode, and is formed on the electron transport layer on which the photosensitizer and / or coadsorbent is adsorbed in order to shorten the hole transport distance. As the second electrode, an inorganic conductor such as metal or carbon, or an organic conductor can be used, but an organic conductor is preferable.
As the organic conductor, a donor compound and an acceptor compound can be used in combination.

  Examples of the donor compound include a compound represented by the following general formula (7), and a compound represented by the following general formula (9) is preferable.

（式中、Ａｒ２、Ａｒ３は酸素原子、硫黄原子、セレン、またはテルルを含むヘテロ環を表す。）

(In the formula, Ar 2 and Ar 3 represent a heterocycle containing an oxygen atom, a sulfur atom, selenium, or tellurium.)

（式中、Ｒ１５〜Ｒ１８は酸素原子、硫黄原子、セレン原子を表す。）
ドナー性化合物の例を以下に示すが、これらに限定されるものではない。

(In the formula, R15 to R18 represent an oxygen atom, a sulfur atom, and a selenium atom.)
Although the example of a donor compound is shown below, it is not limited to these.

  Examples of the acceptor compound include a compound represented by the following general formula (8), and a compound represented by the following general formula (10) is preferable.

（式中、Ａｒ４は２価のアリーレン、Ｏ、Ｓ、Ｓｅ、またはＮを含むヘテロ環を表し、Ｒ１５、Ｒ１６、Ｒ１７、Ｒ１８は電子吸引性基を表す。）

(In the formula, Ar4 represents a divalent arylene, O, S, Se, or a heterocycle containing N, and R15, R16, R17, and R18 represent an electron-withdrawing group.)

（式中、Ａｒ４は２価のアリーレン、Ｏ、Ｓ、Ｓｅ、またはＮを含むヘテロ環を表す。）
アクセプター性化合物の例をいかに示すが、これらに限定されるものではない。

(In the formula, Ar4 represents a divalent arylene, O, S, Se, or a heterocycle containing N.)
Examples of acceptor compounds are shown below, but are not limited thereto.

Examples of the method for forming the second electrode containing the organic conductor of the present invention include a method of mixing a solution of a donor compound and an acceptor compound, and vacuum film formation such as co-evaporation. A production method is preferred.
Examples of the solution for dissolving the donor compound and the acceptor compound include alcohol solvents such as methanol, ethanol, and isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ethyl formate, ethyl acetate, and acetic acid. Ester solvents such as n-butyl, ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, or N-methyl-2-pyrrolidone Amido solvents, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene , Halogenated hydrocarbon solvents such as bromobenzene, iodobenzene or 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene , Hydrocarbon solvents such as o-xylene, m-xylene, p-xylene, ethylbenzene, and cumene can be used, and these can be used alone or as a mixture of two or more.

  The mixing ratio of the donor compound and the acceptor compound is not particularly limited, but is preferably 0.01 parts by mass to 100 parts by mass of the acceptor compound with respect to 1 part by mass of the donor compound. 1 mass part-10 mass parts are more preferable.

  An organic conductor layer is formed using a solution obtained by dissolving a donor compound and an acceptor compound on a porous electron current collecting electrode on which a photosensitizer is adsorbed using a wet film forming method. The method for forming the organic conductor layer is not particularly limited, and includes a dipping method, a spray method, a wire bar method, a spin coating method, a roller coating method, a blade coating method, a gravure coating method, and a wet printing method such as a relief printing plate, Various methods such as offset, gravure, intaglio, rubber plate, and screen printing can be used.

In the present invention, a collector electrode having a lower resistance may be provided on the organic conductor. As the current collecting electrode, the same one as the above-mentioned electron current collecting electrode can be used, and a support is not necessarily required in a configuration in which strength and sealability are sufficiently maintained.
Specific examples of the current collecting electrode material include metals such as platinum, gold, silver, copper, and aluminum, carbon compounds such as graphite, fullerene, carbon nanotube, and graphene, and conductive metal oxides such as ITO, FTO, and ATO. , Conductive polymers such as polythiophene and polyaniline.
There is no restriction | limiting in particular in the film thickness of a current collection electrode layer, You may use it individually or in mixture of 2 or more types.

  The collector electrode can be formed by a method such as coating, laminating, vapor deposition, CVD, and bonding on the organic conductor as appropriate depending on the type of material used and the type of organic conductor.

In order to operate as a photoelectric conversion element, at least one of the electron collector electrode and the organic conductor must be substantially transparent.
In the photoelectric conversion element of the present invention, a method in which the electron collecting electrode side is transparent and sunlight is incident from the electron collecting electrode side is preferable. In this case, it is preferable to use a material that reflects light on the current collecting electrode side, and glass, plastic, or metal thin film on which metal, conductive oxide is deposited is preferable.
It is also effective to provide an antireflection layer on the sunlight incident side.

<Application>
The photoelectric conversion element of the present invention can be applied to a solar cell and a power supply device using the solar cell.
As an application example, any device can be used as long as it has conventionally used a solar cell or a power supply device using the solar cell.
For example, although it may be used for an electronic desk calculator or a solar cell for a wristwatch, examples of utilizing the characteristics of the photoelectric conversion element of the present invention include power supply devices such as a mobile phone, an electronic notebook, and electronic paper. It can also be used as an auxiliary power source for extending the continuous use time of a rechargeable or dry battery type electric appliance.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example.
[Synthesis example]

Synthesis of (Exemplary Compound A-22) 0.26 g of an aldehyde compound represented by the following (E-1), 0.084 g of a rhodanine compound represented by the following (E-2), and 9.24 mg of ammonium acetate in 10 ml of acetic acid, The mixture was heated and stirred at 120 ° C. for 4 hours and 20 minutes under a nitrogen stream.
After cooling to room temperature, the reaction solution was transferred to a separatory funnel and extracted with ethyl acetate. The organic layer was washed twice with water, separated, dried over magnesium sulfate, and the solvent was distilled off.
The residue was purified by silica gel column chromatography (eluent: ethyl acetate / methylene chloride = 1/1) to obtain 0.116 g of the desired product (A-22) as a black solid. Yield 44.7%. The IR spectrum is shown in FIG.

Synthesis of (Exemplary Compound A-07) 0.20 g of the aldehyde compound represented by the following (E-3), 65 mg of the rhodanine compound represented by (E-2) and 7.2 mg of ammonium acetate in 10 ml of acetic acid in a nitrogen stream Under stirring at 120 ° C. for 2 hours.
After cooling to room temperature, the reaction solution is transferred to a separatory funnel and extracted with toluene. The organic layer was washed twice with water, separated, dried over magnesium sulfate, and the solvent was distilled off.
The residue was purified by silica gel column chromatography (eluent: ethyl acetate / toluene = 1/1) to obtain 0.116 g of the desired product (A-07) as a reddish purple solid. Yield 45.2%. The IR spectrum is shown in FIG.

Synthesis of (Exemplary Compound A-23) 0.15 g of an aldehyde compound represented by the following (E-4), 44.6 mg of rhodanine compound represented by (E-2), and 4.89 mg of ammonium acetate in 10 ml of acetic acid, The mixture was heated and stirred at 120 ° C. for 2 hours under a nitrogen stream.
After cooling to room temperature, the reaction solution is transferred to a separatory funnel and extracted with toluene. The organic layer was washed twice with water, separated, dried over magnesium sulfate, and the solvent was distilled off. The residue was purified by silica gel column chromatography (eluent: ethyl acetate / toluene = 1/1) to obtain 0.05 g of the desired product (A-23) as a black solid. Yield 26.6%. The IR spectrum is shown in FIG.

Synthesis of (Exemplary Compound A-24) 0.335 g of the aldehyde compound represented by the following (E-5), 39.3 mg of cyanoacetic acid, and 78.6 mg of piperidine were added to 6.7 ml of acetonitrile at 80 ° C. in a nitrogen stream at 4 ° C. Stir with heating for hours. 3 ml of chlorobenzene was added and the mixture was further heated and stirred at the same temperature for 2 hours.
After cooling to room temperature, the reaction solution is transferred to a separatory funnel and extracted with toluene. The organic layer was washed twice with water, separated, dried over magnesium sulfate, and the solvent was distilled off. The residue was purified by silica gel column chromatography (eluent: ethyl acetate / toluene = 1/3) to obtain 0.05 g of a red amorphous target product (A-23). Yield 26.6%. The IR spectrum is shown in FIG.

Synthesis of (Exemplary Compound B-09) 0.333 g of phosphonic acid ethyl ester represented by the following (E-6) was dissolved in 6 ml of methylene chloride, and nitrogen bubbling was performed for 2 hours while stirring at room temperature.
0.156 g of trimethylsilyl iodide was slowly added and stirred at room temperature for 24 hours.
Methanol was added to the reaction solution, and distillation was repeated 6 times under reduced pressure. The precipitated crystals were washed with methanol and filtered to obtain 0.29 g of the desired product (B-09) as light red crystals. Yield 90.9%.
The IR spectrum is shown in FIG.

[Example 1]
(Production of titanium oxide semiconductor electrode)
Titanium tetra-n-propoxide (2 ml), acetic acid (4 ml), ion exchange water (1 ml), and 2-propanol (40 ml) were mixed, spin-coated on an FTO glass substrate, dried at room temperature, and baked at 450 ° C. for 30 minutes in air. On the obtained electrode, the same solution was again applied by spin coating so as to have a film thickness of 100 nm, and baked in air at 450 ° C. for 30 minutes to form a dense electron transport layer.

Bead mill with 3 g of titanium oxide (ST-21 manufactured by Ishihara Sangyo Co., Ltd.), 0.2 g of acetylacetone, and 0.3 g of surfactant (polyoxyethylene octylphenyl ether manufactured by Wako Pure Chemical Industries, Ltd.) together with 5.5 g of water and 1.0 g of ethanol The treatment was applied for 12 hours.
1.2 g of polyethylene glycol (# 20,000) was added to the obtained dispersion to prepare a paste.
This paste was applied onto the dense electron transport layer so as to have a film thickness of 2 μm, dried at room temperature, and then baked in air at 500 ° C. for 30 minutes to form a porous electron transport layer.

  The titanium oxide semiconductor electrode was allowed to stand in a dark place at room temperature for 15 hours in a chlorobenzene solution of a photosensitized compound represented by the exemplified compound (A-22) adjusted to 0.5 mM to obtain a photosensitized compound. Adsorbed.

(Adjustment of organic conductor solution)
A solution of tetrathiafulvalene (C-01) in acetonitrile adjusted to 0.5 mM and a solution of tetracyanoquinodimethane (D-02) in acetonitrile adjusted to 0.5 mM at room temperature to a mass ratio of 1: 1. The organic conductor solution was prepared by mixing with stirring.

(Production and evaluation of dye-sensitized solar cells)
The prepared organic conductor solution was cast on the titanium oxide semiconductor electrode on which the photosensitizing compound was adsorbed, and dried at room temperature to prepare a dye-sensitized solar cell.
The photoelectric conversion efficiency of this photoelectric conversion element under pseudo-sunlight irradiation (AM1.5, 100 mW / cm ² ) is as follows: open-circuit voltage = 0.64 V, short-circuit current density 2.5 mA / cm ² , form factor = 0.55, The conversion efficiency was 0.88%, and there was no short circuit.

[Example 2]
The chlorobenzene solution of the photosensitizing compound in Example 1 was changed to a chlorobenzene solution of n-decylphosphonic acid adjusted to the photosensitizing compound shown by the exemplified compound (A-22) adjusted to 0.5 mM and 0.2 mM. A dye-sensitized solar cell was prepared and evaluated in the same manner as in Example 1 except that.
As a result, an open circuit voltage = 0.70 V, a short circuit current density of 2.2 mA / cm ² , a form factor = 0.57, a conversion efficiency = 0.88%, and there were no shorted portions.

[Example 3]
A dye was prepared in the same manner as in Example 1 except that the chlorobenzene solution of the photosensitizing compound in Example 1 was changed to the chlorobenzene solution of the photosensitizing compound represented by Exemplary Compound (A-07) adjusted to 0.5 mM. A sensitized solar cell was prepared and evaluated.
As a result, the open-circuit voltage = 0.62 V, the short-circuit current density 2.6 mA / cm ² , the form factor = 0.56, the conversion efficiency = 0.90%, and there was no short-circuited portion.

[Example 4]
A dye was prepared in the same manner as in Example 1 except that the chlorobenzene solution of the photosensitizing compound in Example 1 was changed to the chlorobenzene solution of the photosensitizing compound represented by Exemplary Compound (A-23) adjusted to 0.5 mM. A sensitized solar cell was prepared and evaluated.
As a result, the open-circuit voltage = 0.62 V, the short-circuit current density 2.7 mA / cm ² , the form factor = 0.55, the conversion efficiency = 0.92%, and there was no short-circuited portion.

[Example 5]
The chlorobenzene solution of the photosensitized compound in Example 1 was changed to the chlorobenzene solution of n-decylphosphonic acid adjusted to the photosensitized compound shown by the exemplary compound (A-23) adjusted to 0.5 mM and 0.2 mM. A dye-sensitized solar cell was prepared and evaluated in the same manner as in Example 1 except that.
As a result, the open-circuit voltage = 0.71 V, the short-circuit current density 2.7 mA / cm ² , the form factor = 0.56, the conversion efficiency = 1.07%, and there was no short-circuited portion.

[Example 6]
The chlorobenzene solution of the photosensitizing compound in Example 1 is represented by a photosensitizing compound represented by exemplary compound (A-22) adjusted to 0.5 mM and an exemplary compound (B-09) adjusted to 4.0 mM. A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 1 except that the co-adsorbent was changed to a chlorobenzene solution.
As a result, the open-circuit voltage = 0.72 V, the short-circuit current density 2.3 mA / cm ² , the form factor = 0.55, the conversion efficiency = 0.91%, and there was no short-circuited portion.

[Example 7]
The chlorobenzene solution of the photosensitizing compound in Example 1 is represented by the photosensitizing compound represented by the exemplary compound (A-22) adjusted to 0.5 mM and the exemplary compound (B-15) adjusted to 5.0 mM. A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 1 except that the co-adsorbent was changed to a chlorobenzene solution.
As a result, the open-circuit voltage = 0.69 V, the short-circuit current density 2.2 mA / cm ² , the form factor = 0.56, the conversion efficiency = 0.85%, and there was no short-circuited portion.

[Example 8]
The chlorobenzene solution of the photosensitizing compound in Example 1 is represented by a photosensitizing compound represented by exemplary compound (A-22) adjusted to 0.5 mM and an exemplary compound (B-21) adjusted to 3.0 mM. A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 1 except that the co-adsorbent was changed to a chlorobenzene solution.
As a result, the open circuit voltage = 0.69 V, the short circuit current density 2.3 mA / cm ² , the form factor = 0.55, the conversion efficiency = 0.87%, and there was no short circuit.

[Example 9]
The photosensitizing compound and co-adsorbent in Example 6 were co-expressed by the compound represented by D358 below (manufactured by Mitsubishi Paper Industries) adjusted to 0.5 mM and the exemplified compound (B-09) adjusted to 2.0 mM. A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 6 except that the adsorbent was changed.
As a result, the open-circuit voltage = 0.56V, the short-circuit current density 2.9 mA / cm ² , the form factor = 0.50, the conversion efficiency = 0.81%, and there was no short-circuited portion.

[Example 10]
The photosensitizing compound and co-adsorbent in Example 6 were co-expressed with the compound represented by D358 (manufactured by Mitsubishi Paper Industries) adjusted to 0.5 mM and the exemplified compound (B-09) adjusted to 4.0 mM. A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 6 except that the adsorbent was changed.
As a result, the open circuit voltage = 0.59V, the short circuit current density 2.8 mA / cm ² , the form factor = 0.51, the conversion efficiency = 0.84%, and there was no short-circuited portion.

[Example 11]
The photosensitizing compound and co-adsorbent in Example 6 were co-expressed with the compound represented by D358 (manufactured by Mitsubishi Paper Industries) adjusted to 0.5 mM and the exemplified compound (B-09) adjusted to 8.0 mM. A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 6 except that the adsorbent was changed.
As a result, the open circuit voltage = 0.61 V, the short circuit current density 2.6 mA / cm ² , the form factor = 0.53, the conversion efficiency = 0.84%, and there was no short-circuited portion.

[Example 12]
The photosensitizing compound and co-adsorbent in Example 7 were the compound represented by D358 (manufactured by Mitsubishi Paper Industries) adjusted to 0.5 mM and the exemplified compound (B-15) adjusted to 5.0 mM. A dye-sensitized solar cell was produced and evaluated in the same manner as in Example 7 except that the adsorbent was changed.
As a result, the open-circuit voltage = 0.57 V, the short-circuit current density 2.6 mA / cm ² , the form factor = 0.52, the conversion efficiency = 0.77%, and there was no short-circuited portion.

[Example 13]
N719 (manufactured by Solaronix: cis-Di (thiocyanato) -N, N′-bis (2,2′-bipyrylyl-) in which the photosensitizing compound and the co-adsorbent in Example 8 were adjusted to 0.5 mM. 4,4 ′ dicarboxylic acid) -Ruthenium (II)) and the co-adsorbent represented by the exemplified compound (B-21) adjusted to 3.0 mM, and the dye-sensitized solar in the same manner as in Example 8. A battery was made and evaluated.
As a result, the open-circuit voltage = 0.59V, the short-circuit current density 2.7 mA / cm ² , the form factor = 0.52, the conversion efficiency = 0.83%, and there was no short-circuited portion.

[Example 14]
The organic conductor solution in Example 1 was changed to a chlorobenzene solution of tetrathiafulvalene (C-01) adjusted to 0.5 mM and a chlorobenzene solution of tetracyanoquinodimethane (D-02) adjusted to 0.5 mM. Except for the above, dye-sensitized solar cells were prepared and evaluated in the same manner as in Example 1.
As a result, the open-circuit voltage = 0.71 V, the short-circuit current density 3.0 mA / cm ² , the form factor = 0.55, the conversion efficiency = 1.17%, and there was no short-circuited portion.

[Example 15]
The organic conductor solution in Example 1 was changed to a tetrahydrofuran solution of tetrathiafulvalene (C-01) adjusted to 0.5 mM and a tetrahydrofuran solution of tetracyanoquinodimethane (D-02) adjusted to 0.5 mM. Except for the above, dye-sensitized solar cells were prepared and evaluated in the same manner as in Example 1.
As a result, the open circuit voltage was 0.70 V, the short circuit current density was 2.7 mA / cm ² , the form factor was 0.56, the conversion efficiency was 1.06%, and there was no short-circuited portion.

[Example 16]
The organic conductor solution in Example 9 was changed to a tetrahydrofuran solution of tetrathiafulvalene (C-01) adjusted to 0.5 mM and a tetrahydrofuran solution of tetracyanoquinodimethane (D-02) adjusted to 0.5 mM. Except for the above, dye-sensitized solar cells were prepared and evaluated in the same manner as in Example 9.
As a result, the open-circuit voltage = 0.60 V, the short-circuit current density 2.9 mA / cm ² , the form factor = 0.52, the conversion efficiency = 0.90%, and there was no short-circuited portion.

[Example 17]
The organic conductor solution in Example 16 was changed to a chlorobenzene solution of (C-04) adjusted to 0.5 mM and a chlorobenzene solution of (D-09) adjusted to 0.5 mM, as in Example 16. A dye-sensitized solar cell was prepared and evaluated.
As a result, the open circuit voltage = 0.59V, the short circuit current density 2.9 mA / cm ² , the form factor = 0.52, the conversion efficiency = 0.89%, and there was no short circuit.

[Example 18]
The organic conductor solution in Example 16 was changed to a chlorobenzene solution of (C-11) adjusted to 0.5 mM and a chlorobenzene solution of (D-09) adjusted to 0.5 mM, as in Example 16. A dye-sensitized solar cell was prepared and evaluated.
As a result, the open-circuit voltage = 0.59V, the short-circuit current density 2.7 mA / cm ² , the form factor = 0.52, the conversion efficiency = 0.83%, and there was no short-circuited portion.

[Example 19]
The organic conductor solution in Example 17 was changed to a tetrahydrofuran solution of (C-04) adjusted to 0.5 mM and a tetrahydrofuran solution of (D-09) adjusted to 0.5 mM, as in Example 16. A dye-sensitized solar cell was prepared and evaluated.
As a result, the open-circuit voltage = 0.59V, the short-circuit current density 2.9 mA / cm ² , the form factor = 0.52, the conversion efficiency = 0.89%, and there was no short-circuited portion.

[Example 20]
The organic conductor solution in Example 18 was changed to a tetrahydrofuran solution of (C-11) adjusted to 0.5 mM and a tetrahydrofuran solution of (D-09) adjusted to 0.5 mM, as in Example 18. A dye-sensitized solar cell was prepared and evaluated.
As a result, the open-circuit voltage = 0.59V, the short-circuit current density 2.7 mA / cm ² , the form factor = 0.52, the conversion efficiency = 0.83%, and there was no short-circuited portion.

[Comparative Example 1]
Dye sensitization was carried out in the same manner as in Example 1 except that the chlorobenzene solution of the photosensitized compound in Example 1 was changed to a chlorobenzene solution of the compound represented by D358 (manufactured by Mitsubishi Paper Industries) adjusted to 0.5 mM. Type solar cells were fabricated and evaluated.
However, this solar cell was short-circuited (both open-circuit voltage and short-circuit current density were 0), and did not show solar cell characteristics. It is considered that this is not functioning as a solar cell because there is a portion short-circuited by contact between titanium oxide or titanium oxide adsorbing a dye and an organic conductor.

[Comparative Example 2]
The chlorobenzene solution of the photosensitized compound in Example 1 was changed to the chlorobenzene solution of n-decylphosphonic acid adjusted to 1.0 mM and the compound represented by D358 (manufactured by Mitsubishi Paper Industries) adjusted to 0.5 mM. Produced and evaluated a dye-sensitized solar cell in the same manner as in Example 1.
However, this solar cell was short-circuited (both open-circuit voltage and short-circuit current density were 0), and did not show solar cell characteristics. It is considered that this is not functioning as a solar cell because there is a portion short-circuited by contact between titanium oxide or titanium oxide adsorbing a dye and an organic conductor.

  As is apparent from the above, the dye-sensitized solar cell of the present invention comprises an electron transporting compound containing at least one of a photosensitizing compound bound to a hole transporting material skeleton or a coadsorbent bound to a hole transporting material. It can be seen that a photoelectric property is exhibited by covering the top and providing a conductive compound layer containing an organic conductor thereon.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 1st electrode 3 Electron transport layer 4 Dense electron transport layer 5 Porous electron transport layer 6 Photosensitizer 7 Coadsorbent 8 Second electrode 9 Lead line 10 Lead line

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

Nature, 353 (1991) 737 J. Am. Chem. Soc., 115 (1993) 6382 Semicond. Sci. Technol., 10 (1995) 1689 Electrochemistry, 70 (2002) 432 Synthetic Metals, 89 (1997) 215 Nature, 398 (1998) 583 Chem. Lett., (1997) 471

Claims (10)

A dye-sensitized solar cell having a first electrode and a second electrode facing the first electrode,
The first electrode is provided with an electron transporting layer, and the electron transporting layer is a photosensitizer in which a sensitizing dye site and a hole transporting site are bonded at a non-conjugated binding site, and / or a hole transporting site and a non-transporting site. A dye-sensitized solar, which is coated with a co-adsorbent having a conjugated binding site, and wherein the second electrode is provided on the photosensitizer and / or the co-adsorbent. battery
The dye-sensitized dye according to claim 1, wherein the non-conjugated bond site of the photosensitizer and the co-adsorbent is a divalent linking group containing an alkylene group and / or an ether group and not covalently bonded. Solar cell.
The photosensitizer is a photosensitizer represented by the following general formula (1), and the coadsorbent is a coadsorbent represented by the following general formula (2). Item 3. The dye-sensitized solar cell according to Item 1 or 2.

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R 1 and R 2 represent a site A 1 necessary for constituting a heterocyclic ring or a heterocyclic residue together with an alkyl group, an aryl group, and an N atom, and R 3 represents A divalent linking group, Ar1 represents a divalent arylene, R4 represents a divalent linking group containing no alkylene group and / or an ether group, and Y represents an acidic group.

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R4 represents a divalent linking group containing an alkylene group and / or an ether group and not covalently bonded. Y represents an acidic group.) The dye-sensitized solar cell according to claim 3, wherein the photosensitizer represented by the general formula (1) is a photosensitizer represented by the following general formula (3).

(In the formula, X represents a hole transporting structure containing a nitrogen atom, R3 represents a divalent linking group, R4 represents a divalent linking group containing an alkylene group and / or an ether group and not a covalent bond. Y is acidic. Ar1 represents a divalent arylene, R5 and R6 each represents a hydrogen atom, an alkyl group or an aryl group, and R5 and R6 may form a cyclic structure.) The dye sensitizing method according to claim 3 or 4, wherein the hole transport structure X containing nitrogen atoms of the general formulas (1) to (3) is a structure represented by the following general formula (4): Sensitive solar cell.

(Wherein R7 and R8 represent an alkyl group, an alkenyl group, an aryl group, a site necessary for forming a heterocyclic ring or a heterocyclic residue together with an N atom, R9 represents a divalent alkylene, a divalent arylene, 2 R7 and R8, R8 and R9, and R7 and R9 may be bonded to each other directly or indirectly through a divalent hydrocarbon to form a cyclic structure. .) The dye-sensitized solar according to claim 4 or 5, wherein the photosensitizer represented by the general formula (3) is a photosensitizer represented by the following general formula (5). battery.

(In the formula, R5 and R6 represent a hydrogen atom, an alkyl group, and an aryl group, and R7 and R8 represent a site necessary for constituting a heterocyclic ring or a heterocyclic residue together with an alkyl group, an alkenyl group, an aryl group, and an N atom. R9 represents a divalent alkylene, a divalent arylene, a divalent heterocycle, and R7 and R8, R8 and R9, and R7 and R9 are each directly or via a divalent hydrocarbon. R10 and R11 each represents an oxygen atom or a sulfur atom, R12 represents an oxygen atom, a sulfur atom, a dicyanomethylene group, or a rhodanine ring, and R13 represents a divalent ring. (Alkylene represents a divalent arylene, Ar1 represents a divalent arylene, and n represents an integer of 2 to 18.) The dye-sensitized type according to any one of claims 3 to 6, wherein the co-adsorbent represented by the general formula (2) is a co-adsorbent represented by the following general formula (6). Solar cell.

(Wherein R7 and R8 represent an alkyl group, an alkenyl group, an aryl group, a site necessary for forming a heterocyclic ring or a heterocyclic residue together with an N atom, R9 represents a divalent alkylene, a divalent arylene, 2 R7 and R8, R8 and R9, and R7 and R9 may be bonded to each other directly or indirectly through a divalent hydrocarbon to form a cyclic structure. R14 represents divalent alkylene or arylene, n represents an integer of 2 to 18, and m represents 0 or 1.)   The dye-sensitized solar cell according to any one of claims 1 to 7, wherein the electron transport layer is formed of an n-type oxide semiconductor made of nanoparticles.   The dye-sensitized solar cell according to claim 8, wherein the oxide semiconductor is selected from at least one of titanium oxide, zinc oxide, tin oxide, and niobium oxide. The second electrode contains an organic conductor, and the organic conductor contains a donor compound represented by the following general formula (7) and an acceptor compound represented by the following general formula (8). The dye-sensitized solar cell according to any one of claims 1 to 9, wherein:

(In the formula, Ar 2 and Ar 3 represent a heterocycle containing an oxygen atom, a sulfur atom, selenium, or tellurium.)

(In the formula, Ar4 represents a divalent arylene, O, S, Se, or a heterocycle containing N, and R15, R16, R17, and R18 represent an electron-withdrawing group.)

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