JP2012221778A - Photoelectric conversion element, method for manufacturing photoelectric conversion element, and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion element using an electroconductive polymer as a hole transport material and stably maintaining the photoelectric conversion efficiency at a high level.SOLUTION: The photoelectric conversion element comprises at least a substrate, a first electrode, a photoelectric conversion layer containing a semiconductor and a sensitizing dye, a hole transport layer containing a solid hole transport material, a second electrode, and a region which absorbs light with wavelengths of 380 nm or shorter. The solid hole transport material in the hole transport layer is an electroconductive polymer.

Description

  The present invention relates to a photoelectric conversion element having a function of converting light energy into electric energy, and more particularly to a dye-sensitized photoelectric conversion element using a solid material as a hole transport material.

  Photoelectric conversion elements typified by solar cells are elements that convert light energy into electrical energy and supply power to various devices. Development of photoelectric conversion elements that use inorganic materials typified by silicon has traditionally been developed. Has been studied. Inorganic materials include single crystal silicon, amorphous silicon, indium copper selenide, etc., but photoelectric conversion elements using inorganic materials produce a purification process or multilayer pn junction structure that forms high-purity inorganic materials. There is a problem in productivity, such as the need for a manufacturing process. In addition, since a rare metal such as indium is used, there is a problem with a stable supply system of raw materials.

  On the other hand, photoelectric conversion elements using organic materials that can be stably supplied by synthesis have also been studied, for example, bonding of electron-conductive (n-type) perylenetetracarboxylic acid and hole-conductive (p-type) copper phthalocyanine. A reported organic photoelectric conversion element has been reported (for example, see Non-Patent Document 1). In such an organic photoelectric conversion element, it has been found that the exciton diffusion length and the space charge layer need to be improved. As a countermeasure, the area of the pn junction formed by the n-type organic material and the p-type organic material is used. There has been proposed a method for increasing photoelectric conversion so that photoelectric conversion can be performed efficiently. Specifically, a technique has been proposed in which an n-type electron conductive material and a p-type hole conductive polymer are combined in the film to increase the pn junction portion, thereby performing photoelectric conversion throughout the film. (For example, see Non-Patent Document 2). A technique has also been proposed in which a conjugated polymer as a hole conducting polymer and a fullerene as an electron conducting material are combined in a film.

  By the way, since the organic photoelectric conversion element has a lower photoelectric conversion efficiency than that using an inorganic material, improvement of the photoelectric conversion efficiency has been studied, and as a technique for solving this, a dye-sensitized photoelectric conversion device is used. The conversion element attracted attention. Specifically, a technique for improving the photoelectric conversion efficiency by increasing the adsorption amount of the organic sensitizing dye by increasing the surface area of the semiconductor using porous titanium oxide has been proposed (for example, non-patented). Reference 3). In this technique, an organic sensitizing dye adsorbed on the porous titanium oxide surface is photoexcited, and electrons are injected from the dye into titanium oxide to form a dye cation. The presence of this dye cation repeats the electron transfer cycle from the counter electrode via the hole transport layer having an electrolyte solution in which an iodine-containing electrolyte is dissolved in an organic solvent, thereby improving the photoelectric conversion efficiency. Is realized. In addition, with this technology, titanium oxide used as a semiconductor is not purified to a high purity, and the visible light region where photoelectric conversion is possible has been expanded, and the possibility of a dye-sensitized photoelectric conversion element has been expanded. It was also something to raise. On the other hand, since an electrolytic solution is used for the hole transport layer, consideration must be given to prevent the dissipation of chemical species due to liquid leakage.

  In order to solve this problem, a technique related to an all-solid dye-sensitized photoelectric conversion element using a solid material such as an amorphous organic hole material or copper iodide as a hole transport material has been proposed (for example, Non-Patent Document 4, 5). Among these solid hole transport materials, one that is expected to obtain high photoelectric conversion efficiency due to its structure is a conductive polymer represented by PEDOT (polyethylenedioxythiophene) and the like, and has been studied. (For example, refer to Patent Documents 1 and 2 and Non-Patent Document 6).

  For example, in Patent Document 1, polythiophene, which is one of conductive polymers, is used as a hole transport material, and holes are formed on a semiconductor fine particle-containing layer on which a dye is adsorbed by an electrolytic polymerization method or a coating method. A technique for forming a transport layer is disclosed. Patent Document 2 discloses a technique for producing a solar cell unit by applying a coating solution containing polyethylenedioxythiophene, which is one of polythiophenes, onto a first electrode.

JP 2000-106223 A JP 2011-009419 A

C. W. Tang: Applied Physics Letters, 48, 183 (1986) G. Yu, J .; Gao, J .; C. Humelen, F.M. Wudl and A.W. J. et al. Heeger: Science, 270, 1789 (1996). B. O'Regan, M.M. Gratzel, Nature, 353, 737 (1991) U. Bach, D.C. Lupo, P.M. Comte, J .; E. Moser, F.A. Weissortel, J. et al. Salbeck, H.M. Spreitzer and M.M. Gratzel, Nature, 395, 583 (1998) G. R. A. Kumara, S .; Kaneko, M .; Kuya, A .; Konno and K.K. Tennakone: Key Engineering Materials, 119, 228 (2002) J. et al. Xia, N .; Masaki, M .; Lira-Cantu, Y.M. Kim, K .; Jiang and S.J. Yanagida: Journal of the American Chemical Society, 130, 1258 (2008)

  As described above, the development of photoelectric conversion elements using conductive polymers as hole transport materials has been studied. As the study progressed, the high level expected even when using conductive polymers was studied. It has been found that the photoelectric conversion efficiency is not always obtained. That is, when a conductive polymer is used as the hole transport material, charge recombination is likely to occur in the hole transport layer, which is a factor that hinders improvement in photoelectric conversion efficiency. In addition, although high photoelectric conversion efficiency was obtained in the initial stage, some of the photoelectric conversion efficiency decreased with time, and it has been found that there is a problem in maintaining the photoelectric conversion efficiency stably over a long period of time.

  The present invention has been made in view of the above-mentioned problems, and it is possible to obtain a high photoelectric conversion efficiency by using a conductive polymer as a hole transport material, and to stably maintain the photoelectric conversion efficiency at a high level. An object of the present invention is to provide a possible dye-sensitized photoelectric conversion element.

The present inventor has found that the above-described problem can be solved by any of the configurations described below. That is, the invention described in claim 1
“At least a substrate, a first electrode, a photoelectric conversion layer containing a semiconductor and a sensitizing dye, a hole transport layer containing a solid hole transport material, and a photoelectric conversion element having a second electrode,
While having a region that absorbs light of a wavelength of 380 nm or less from the surface on which light is incident to the electrode located on the surface side,
The solid hole transport material contained in the hole transport layer is a conductive polymer formed by polymerizing a compound having a structure represented by any one of the following general formulas (1) to (3). The photoelectric conversion element characterized by the above-mentioned.

(In the formula, R _{1 to} R ₄ represent any one of a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, and an aryl group, and R _{1 to} R ₄ are the same or different. May be.)

(In the formula, R ₅ represents any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, n represents an integer of 1 or 2, and m represents an integer of 0 to 2n + 4.)

(In the formula, R _{6 to} R ₉ represent any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, and R _{6 to} R ₉ may be the same or different. .) ”.

The invention described in claim 2
“At least one of R _{1 to} R ₄ in the compound having the structure represented by the general formula (1) is
An alkyl group having 6 to 14 carbon atoms or a cycloalkyl group, an aryl group having 6 or more carbon atoms, or an alkyl group having an oxyethylene group,
R ₅ in the compound having the structure represented by the general formula (2) is either an aryl group having 6 or more carbon atoms or an alkyl group having an oxyethylene group, and the value of n is 1. ,
At least one of R _{6 to} R ₉ in the compound having a structure represented by the general formula (3) is:
2. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion element is any one of an alkyl group having 6 or more carbon atoms, an aryl group having 6 or more carbon atoms, and an alkyl group having an oxyethylene group. ].

The invention according to claim 3
"The photoelectric conversion element
3. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion element is manufactured through a step of performing a heat treatment after forming the photoelectric conversion layer and the hole transport layer. ].

The invention according to claim 4
The process temperature of the heat treatment performed after forming the photoelectric conversion layer and the hole transport layer is 70 ° C. or higher and 150 ° C. or lower. ].

The invention described in claim 5
[5] The photoelectric conversion element according to any one of claims 1 to 4, wherein the region that absorbs light having a wavelength of 380 nm or less is provided in the base. ].

The invention described in claim 6
“A region that absorbs light having a wavelength of 380 nm or less is
6. The photoelectric conversion device according to claim 1, comprising any one of a benzophenone compound, a benzotriazole compound, a benzoate compound, and a triazine compound. ].

The invention described in claim 7
“A region that absorbs light having a wavelength of 380 nm or less is
The photoelectric conversion element according to any one of claims 1 to 5, which contains either zinc oxide or titanium oxide. ].

The invention according to claim 8 provides:
The photoelectric conversion element according to any one of claims 1 to 7, wherein the photoelectric conversion layer contains titanium oxide having a porous structure. ].

The invention according to claim 9 is:
“At least a first electrode, a photoelectric conversion layer containing a semiconductor and a sensitizing dye, a hole transport layer containing a solid hole transport material, a second electrode, and a region that absorbs light having a wavelength of 380 nm or less. A method for producing a photoelectric conversion element having the above,
The manufacturing method of the photoelectric conversion element is at least:
A region for absorbing light having a wavelength of 380 nm or less is provided from the surface on which light is incident to the electrode located on the surface side, and
A method for producing a photoelectric conversion element comprising a step of polymerizing a compound having a structure represented by any one of the following general formulas (1) to (3) to form a hole transport layer.

(In the formula, R _{1 to} R ₄ represent any one of a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, and an aryl group, and R _{1 to} R ₄ are the same or different. May be.)

(In the formula, R ₅ represents any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, n represents an integer of 1 or 2, and m represents an integer of 0 to 2n + 4.)

(In the formula, R _{6 to} R ₉ represent any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, and R _{6 to} R ₉ may be the same or different. .) ”.

The invention according to claim 10 is:
“At least one of R _{1 to} R ₄ in the compound having the structure represented by the general formula (1) is an alkyl or cycloalkyl group having 6 to 14 carbon atoms, or aryl having 6 or more carbon atoms. Group, an alkyl group having an oxyethylene group,
R ₅ in the compound having the structure represented by the general formula (2) is either an aryl group having 6 or more carbon atoms or an alkyl group having an oxyethylene group, and the value of n is 1. ,
An alkyl having at least one of R _{6 to} R ₉ in the compound having the structure represented by the general formula (3) having an alkyl group having 6 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an oxyethylene group The method for producing a photoelectric conversion element according to claim 9, wherein the method is any one of groups. ].

The invention according to claim 11
[The photoelectric conversion device according to claim 9 or 10, wherein the method for manufacturing the photoelectric conversion element includes a step of performing a heat treatment after the photoelectric conversion layer and the hole transport layer are formed. Device manufacturing method. ].

The invention according to claim 12
“The method for producing a photoelectric conversion element according to claim 11, wherein a temperature of the heat treatment performed after forming the photoelectric conversion layer and the hole transport layer is 70 ° C. or higher and 150 ° C. or lower. ].

The invention according to claim 13
[A photoelectric conversion element according to any one of claims 1 to 8 or a photoelectric conversion element manufactured by the method for manufacturing a photoelectric conversion element according to any one of claims 9 to 12] Solar cell. ].

  In the present invention, charge recombination that is likely to occur when a conductive polymer is used by providing a region that absorbs light with a wavelength of 380 nm or less for a photoelectric conversion element containing a conductive polymer in a hole transport layer. It has become possible to stably maintain the photoelectric conversion efficiency at a high level by suppressing the occurrence of the above.

It is a schematic cross section which shows an example of the photoelectric conversion element which concerns on this invention. It is a schematic diagram which shows the relationship between the numerical value of "shape factor FF", and the shape of a "voltage-current characteristic graph."

  The present invention relates to a dye-sensitized photoelectric conversion element in which an organic sensitizing dye is adsorbed on a semiconductor surface, and more particularly to a dye-sensitized photoelectric conversion element using a conductive polymer as a hole transport material.

  Hereinafter, the present invention will be described in detail. The “conductive polymer formed by polymerizing a compound having a structure represented by any of the general formulas (1) to (3)” in the present invention has double bonds and single bonds alternately. It is a polymer having a conjugated main chain structure called a lined polyene structure. This polymer exhibits conductivity by the charge imparted by the addition of a donor or acceptor moving through the main chain of the π-conjugated structure. The “conductive polymer formed by polymerizing a compound having a structure represented by any of the general formulas (1) to (3)” specifically contains a sulfur atom in the main chain. It is generally called “polythiophene polymer” or “polythiophenes”.

  In addition, the photoelectric conversion element according to the present invention has a “region that absorbs light having a wavelength of 380 nm or less from a surface on which light is incident to an electrode positioned on the surface side”. Here, “from the light incident surface to the electrode positioned on the surface side” refers to a region from the light incident side surface of the photoelectric conversion element to the electrode positioned on the surface side. For example, when light is incident from the surface on the first electrode side as in the photoelectric conversion element 1 shown in FIG. 1 to be described later, the region where the substrate 1, the first electrode 2, and the ultraviolet absorption layer 3 are provided is “light Corresponds to “from the surface on which the light is incident to the electrode positioned on the surface side”. When light is incident from the surface on the second electrode side, the region where the layer existing on the surface on the incident light side from the second electrode is provided is “the electrode positioned on the surface side from the surface on which light is incident. It corresponds to "to".

  Furthermore, as a preferred embodiment of the present invention, there is a "a region that absorbs light having a wavelength of 380 nm or less is provided in the substrate". “The region where light having a wavelength of 380 nm or less is absorbed is provided on the substrate” means that a coating solution or film containing a material that absorbs light having a wavelength of 380 nm or less is applied or pasted to the substrate, or the substrate itself. It means a case having this property.

  First, the structure of the photoelectric conversion element according to the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view schematically showing an example of the structure of a photoelectric conversion element according to the present invention.

  A photoelectric conversion element 10 shown in FIG. 1 includes a substrate 1, a first electrode 2, an ultraviolet absorption layer 3, a photoelectric conversion layer 6, a hole transport layer 7, a second electrode 8, a partition wall 9, and the like. As shown, light is incident on the photoelectric conversion layer 6 from the side where the substrate 1 and the first electrode 2 are disposed. The photoelectric conversion layer 6 contains the semiconductor 5 and the sensitizing dye 4, and the hole transport layer 7 contains a conductive polymer represented by a compound described later as a hole transport material. Further, the substrate 1 is provided with an ultraviolet absorbing layer 3 corresponding to “a region that absorbs light having a wavelength of 380 nm or less” in the present invention.

The photoelectric conversion element 10 is subjected to photoelectric conversion by the following procedure and functions as a battery. That is,
(1) When the first electrode 2 is irradiated with light, the sensitizing dye contained in the photoelectric conversion layer 6 absorbs the light and emits electrons. At this time, the sensitizing dye becomes an oxide.
(2) Electrons emitted by the sensitizing dye move to the semiconductor in the photoelectric conversion layer 6 and further move from the semiconductor to the first electrode 2.
(3) The electrons that have moved to the first electrode 2 travel to the second electrode 8 that is the counter electrode, and reduce the hole transport material at the second electrode.
(4) The aforementioned sensitizing dye oxide receives electrons from the reduced hole transport material and returns to the original state (sensitizing dye).
(5) By repeating the above (1) to (4), the movement of electrons from the first electrode 2 to the second electrode 8 is repeated, and electricity flows.

  As described above, in the photoelectric conversion element 10 of FIG. 1, the sensitizing dye is excited by light irradiation to emit electrons, and the emitted electrons reach the first electrode 2 through the semiconductor and flow to the outside. On the other hand, the sensitizing dye that has become an oxide by emitting electrons functions as a battery by moving the electrons supplied from the second electrode 8 from the hole transport layer and returning to the original state. To do.

  As described above, in the technique of the dye-sensitized photoelectric conversion element, a technique of using a conductive polymer as a hole transport material has been studied in order to improve the photoelectric conversion efficiency. Therefore, it has been difficult to maintain stably. The present inventor presumed the reason why it is difficult for the photoelectric conversion element containing the conductive polymer in the hole transport layer to stably maintain the photoelectric conversion efficiency at a high level.

  First, the conductive polymer used as the hole transport material in the photoelectric conversion element is in a state where the charge formed by the semiconductor is easily moved through the hole transport layer because the dopant is applied at a high concentration. It is considered that. In the photoelectric conversion layer, an organic sensitizing dye adsorbed on a semiconductor surface such as porous titanium oxide is usually photoexcited, and electrons are injected from the organic sensitizing dye into the semiconductor to form a dye cation. Then, the photocurrent is taken out by reducing the dye cation via an external circuit and a hole transport layer. In order to efficiently extract photocurrent to an external circuit, it is important not to generate charge recombination in which electrons injected into the semiconductor and holes in the hole transport layer are combined. The semiconductor and the hole transport layer are required to be electrically insulated.

  However, it was considered that it is very difficult to form and maintain an electrically insulating state between the semiconductor and the hole transport layer when a conductive polymer provided with a high concentration of dopant is used. In addition, it is possible that the molecules constituting the semiconductor and the hole transport layer are likely to be deformed by the generation of heat and the redox reaction, and this effect also maintains the electrical insulation between them. It was a barrier above.

  The present inventor considered that it is important to suppress the occurrence of charge recombination between the semiconductor and the hole transport layer from the above estimation in order to stably maintain the photoelectric conversion efficiency at a high level. Specifically, irradiation with light from which light having a wavelength of 380 nm or less is removed in order to form an electrically insulating state between the semiconductor and the hole transporting layer suppresses improvement in conductivity due to photoexcitation of the semiconductor, and photoelectric conversion efficiency. I thought it would be possible to maintain a stable level at a high level. In addition, even if heat generation and redox reactions are repeated, it is possible to stably maintain the photoelectric conversion efficiency at a high level by suppressing physical contact using a conductive polymer with small deformation. Also thought. As a result of repeated studies, it has been found that the photoelectric conversion element having the above configuration solves the above-described problems.

  The photoelectric conversion element 10 according to the present invention has a “region that absorbs light having a wavelength of 380 nm or less” and a “conductive polymer” that is a solid material as a hole transport material in the hole transport layer 7. It contains. Hereinafter, the “hole transport layer containing a conductive polymer as a solid hole transport material” and the “region that absorbs light having a wavelength of 380 nm or less” constituting the photoelectric conversion element according to the present invention will be described.

  First, a hole transport layer containing a “conductive polymer” that is a solid material as a hole transport material will be described. The hole transport layer 7 provided in the photoelectric conversion element 10 shown in FIG. 1 moves holes toward the second electrode 8 from the sensitizing dye that has been excited by absorbing light and releasing electrons. By doing so, the sensitizing dye is reduced and stabilized. In other words, as described above, the hole transport layer 7 receives electrons from the second electrode 8, passes the received electrons to the sensitizing dye of the photoelectric conversion layer 6 in an excited state, and irradiates the sensitizing dye with light. It returns to the previous state.

  In the present invention, since the conductive polymer described later is used for the hole transport material, there is no occurrence of liquid leakage, which has been a concern for photoelectric conversion elements using an electrolyte as the hole transport material. In addition, since a conductive polymer that easily moves electrons structurally is used for the hole transport material, the hole transport layer can stably transfer electrons from the second electrode to the excited sensitizing dye. This contributes to the development of high photoelectric conversion efficiency. In particular, in the present invention, the hole transport efficiency is improved by the intermolecular interaction by using a conductive polymer formed by polymerizing the compounds represented by the general formulas (1) to (3) described later. As a result, it is considered that the photoelectric conversion efficiency is improved.

  The conductive polymer formed by polymerizing compounds having the structures represented by the following general formulas (1) to (3) is a heterocyclic structure containing a sulfur atom in the main chain (a sulfur-containing heterocyclic structure). It belongs to a polymer called polythiophene having the following. Polymers formed by polymerizing compounds having structures represented by the following general formulas (1) to (3) are conjugates in which double bonds and single bonds that contribute to charge transfer are alternately arranged among polythiophenes. In addition to the main chain structure of the mold, it has a side chain structure. The presence of this side chain structure is considered to improve the crystallinity of the molecule and contribute to the improvement of photoelectric conversion efficiency. In other words, the presence of a site capable of expressing intermolecular interactions in the molecular structure ensures that the formed conductive polymer is regularly arranged and is less likely to cause segmental motion due to heat, thus providing a stable structure. This is considered to form a positive hole transport layer. Moreover, it is considered that the opportunity for the semiconductor and the hole transport layer to approach each other is reduced due to the expression of the intermolecular interaction.

Among these, R < ₁ > -R < ₄ > in the structure represented by the said General formula (1) represents either a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, and an aryl group.

R ₅ in the structure represented by the general formula (2) represents any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group. Moreover, n in the structure represents an integer of 1 or 2, and m represents an integer of 0 to 2n + 4.

Furthermore, R _{6 to} R ₉ in the structure represented by the general formula (3) represent any of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group.

R _{1 to} R ₄ in the structure represented by the general formula (1), R _{5 in} the structure represented by the general formula (2), and R _{6 in the} structure represented by the general formula (3). Examples of the halogen atom represented by to R _9, a chlorine atom, a bromine atom and a fluorine atom. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, pentyl, hexyl, octyl, dodecyl, tridecyl, tetradecyl, pentadecyl and the like. It is done.

In addition, examples of the cycloalkyl group represented by R _{1 to} R ₄ in the structure represented by the general formula (1) include a cyclopentyl group, a cyclohexyl group, and the like, and an oxy group such as a methoxyethoxy group or a methoxyethoxyethoxy group. Some alkyl groups have an ethylene group.

Further, R _{1 to} R ₄ in the structure represented by the general formula (1), R _{5 in} the structure represented by the general formula (2), and the structure represented by the general formula (3) Examples of the alkoxy group represented by R _{6 to} R ₉ include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the aryl group include a phenyl group, a naphthyl group, and an anthracenyl group.

  Specific examples of the compound represented by the general formula (1) are shown below, but the compound represented by the general formula (1) usable in the present invention is not limited to the following.

  Moreover, although the specific example of a compound represented by the said General formula (2) is shown below, the compound represented by General formula (2) which can be used by this invention is not limited to the following.

  Furthermore, although the specific example of a compound represented by the said General formula (3) is shown below, the compound represented by General formula (3) which can be used by this invention is not limited to the following.

  In the present invention, among the compounds represented by the general formulas (1) to (3) that form a conductive polymer called polythiophenes, compounds having the following functional groups are preferably used.

In the compound having the structure represented by the general formula (1), at least one of R _{1 to} R ₄ is an alkyl group or cycloalkyl group having 6 to 14 carbon atoms, or an aryl group having 6 or more carbon atoms. Or an alkyl group having an oxyethylene group R ₅ in the compound having a structure represented by the general formula (2) is an aryl group having 6 or more carbon atoms or an alkyl group having an oxyethylene group Any one and the value of n is 1. At least one of R _{6 to} R ₉ in the compound having the structure represented by the general formula (3) is an alkyl group having 6 or more carbon atoms, carbon One of an aryl group having 6 or more atoms and an alkyl group having an oxyethylene group.

  A photoelectric conversion element using a conductive polymer formed using these preferred compounds as a hole transport material tends to have high photoelectric conversion efficiency as confirmed from the results of Examples described later. have. This is because the conductive polymer formed tends to form a regular molecular arrangement due to the presence of functional groups that can promote intermolecular interactions in the side chain. This is considered to be easier to obtain. Therefore, even under the influence of heat, etc., the molecular chain segmental motion is more strongly suppressed by the intermolecular interaction, and an environment that can suppress charge recombination between the semiconductor represented by titanium oxide and the hole transport layer is formed. Therefore, it is considered that high photoelectric conversion efficiency can be surely obtained.

  The method of polymerizing the compounds represented by the general formulas (1) to (3) is described in, for example, J. Org. R. Reynolds et al .: Adv. Mater. , 11, 1379 (1999), and the like.

  In addition, a hole transport layer containing a conductive polymer formed using the compounds represented by the general formulas (1) to (3) as a solid hole transport material can be manufactured by a known method. is there. Specifically, there is a method in which a coating solution containing a polymer is prepared, and the coating solution is formed on a photoelectric conversion layer by a known method. Examples of the coating method used for forming the hole transport layer include a dipping method, a dropping method, a doctor blade method, a spin coating method, a brush coating method, a spray coating method, and a roll coater method. Moreover, as a solvent for coating liquid, the organic solvent applicable to the following polar solvents and aprotic solvents can be used, for example. That is, examples of the polar solvent include tetrahydrofuran (THF), butylene oxide, chloroform, cyclohexanone, chlorobenzene, acetone, and various alcohols. Examples of the aprotic solvent include dimethylformamide (DMF), acetonitrile, dimethoxyethane, dimethyl sulfoxide, hexamethylphosphoric triamide and the like.

  In addition to the method of forming using a coating solution containing a polymer, a solution containing a compound represented by general formulas (1) to (3), a polymerization catalyst, a polymerization rate adjusting agent, or the like is used as a photoelectric conversion layer. There is also a method in which a hole transport layer is formed by applying or dipping it onto the surface and performing a polymerization reaction. The conditions for the polymerization reaction vary depending on the types and ratios of the compounds represented by the general formulas (1) to (3), the polymerization catalyst, the polymerization rate regulator, the layer thickness to be formed, etc. In this case, the heating temperature is preferably set to 25 ° C. to 120 ° C. and the heating time is set to 1 minute to 24 hours.

  In addition, the manufacturing method of the photoelectric conversion element which concerns on this invention is demonstrated in detail later.

  Next, the “region that absorbs light having a wavelength of 380 nm or less” provided in the photoelectric conversion element according to the present invention will be described. A photoelectric conversion element 10 shown in FIG. 1 has an ultraviolet absorption layer 3 corresponding to the “region that absorbs light having a wavelength of 380 nm or less” in the present invention on a substrate 1.

  A photoelectric conversion element 10 shown in FIG. 1 makes light incident on the photoelectric conversion layer 6 from the side where the substrate 1 and the first electrode 2 are arranged, and absorbs ultraviolet rays between the substrate 1 and the photoelectric conversion layer 6. Layer 3 is provided. That is, in this invention, the area | region (ultraviolet absorption layer 3) which absorbs light with a wavelength of 380 nm or less is provided in the light incident side with respect to the photoelectric converting layer 6.

  The region (ultraviolet absorption layer 3) that absorbs light having a wavelength of 380 nm or less is a commercially available ultraviolet absorption film using a known organic compound or inorganic compound such as a benzophenone compound or a benzotriazole compound used as an ultraviolet absorber. It is possible to form with an ultraviolet absorbing paint. A compound used as an ultraviolet absorber exhibits a property that once it is excited when it absorbs ultraviolet rays, it returns to its original state by releasing the absorbed light energy as heat.

  Examples of organic compounds that can be used as the ultraviolet absorber when forming the ultraviolet absorbing layer 3 include benzophenone compounds, benzotriazole compounds, benzoate compounds, and triazine compounds. Here, although the term “system compound” is used for these compounds that are preferably used as ultraviolet absorbers, the term “system compound” is used generically to have the following structures.

Specific examples of benzophenone compounds, benzotriazole compounds, benzoate compounds, and triazine compounds are shown below, but these compounds are not limited to the following. That is,
(1) Benzophenone compounds 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, etc. (2) Benzotriazole compounds 2- (2H-benzotriazole-2 -Yl) -4-t-butylphenol 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2- (3 '-T-butyl-2'-hydroxy-5'-methylphenyl) -5-chlorobenzotriazole 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) benzotriazole, 2- (2 '-Hydroxy-3', 5'-di-t-butylphenyl) benzotriazole 2- [2'-H Roxy-3,5-di (1,1-dimethylbenzyl) phenyl] -2H-benzotriazole, 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1, 3,3-tetramethylbutyl) phenol] and the like (3) benzoate compounds 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate and the like (4) triazine compounds 2 -[4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5-[(octyl) oxy] phenol, 2- [4,6-diphenyl-1, 3,5-triazin-2-yl] -5-[(hexyl) oxy] phenol, etc. The above organic compounds that can be used as UV absorbers are completely dissolved in a solvent, so that a highly transparent UV absorbing layer is formed. This is advantageous.

  Examples of inorganic compounds that can be used as the ultraviolet absorber when forming the ultraviolet absorbing layer 3 include zinc oxide, titanium oxide, iron oxide, cesium oxide, and zirconium oxide. Among these, zinc oxide and titanium oxide are preferable, and zinc oxide is particularly preferable among inorganic compounds because it can form a highly transparent ultraviolet absorbing layer. Titanium oxide has an excellent UV-cutting performance, but it tends to be difficult to form a UV-absorbing layer with high transparency as when zinc oxide is used.

  The ultraviolet absorbing layer formed using the organic compound or the inorganic compound can transmit 90% or more of visible light of 400 nm or more, and can well cut light having a wavelength of 400 nm or less. is there.

  As described above, the “region that absorbs light having a wavelength of 380 nm or less” in the present invention can be formed by a known method such as application of an ultraviolet absorbing film or application of an ultraviolet absorbing paint. Examples of the commercially available ultraviolet absorbing film that can be used in the present invention include “Scotch Tent Window Film RE87CLIS” manufactured by Sumitomo 3M Limited. Moreover, as a commercially available ultraviolet absorbing paint, for example, there is a fluororesin coating material “Obligard” manufactured by AGC Co-Tech Co., Ltd. Furthermore, it is also possible to use a commercially available resin plate or glass plate having ultraviolet absorption performance, for example, an ultraviolet cut glass “UV veil” manufactured by Asahi Glass Co., Ltd.

  In the present invention, “light having a wavelength of 380 nm or less” is so-called ultraviolet light, which is an electromagnetic wave having a wavelength range of 10 nm to 380 nm, which is shorter than visible light and longer than X-rays. This is called ultraviolet light. The photoelectric conversion element 10 shown in FIG. 1 performs photoelectric conversion using light from which light having a wavelength of 380 nm or less is removed by transmitting incident light through the ultraviolet absorption layer 3. The ultraviolet light absorbed by the ultraviolet absorbing layer 3 is mainly in the wavelength region of 200 nm to 380 nm.

  Ultraviolet rays can be classified into near ultraviolet rays, far ultraviolet rays and the like according to wavelengths. That is, those having a wavelength region of 200 nm to 380 nm can be classified as near ultraviolet rays, those having a wavelength region of 10 nm to 200 nm can be classified as far ultraviolet rays, and those having a wavelength region of 1 nm to 10 nm can be classified as extreme ultraviolet rays. Further, from the viewpoint of human health and environmental impact, those having a wavelength region of 315 nm to 380 nm can be classified as UVA, those having a wavelength range of 280 nm to 315 nm can be classified as UVB, and those having a wavelength less than 280 nm can be classified as UVC.

  As described above, the ultraviolet absorption layer 3 of the photoelectric conversion element 10 mainly absorbs light having a wavelength region of 200 nm to 380 nm. This is because the sun rays reaching the ground surface hardly contain ultraviolet rays of less than 200 nm. That is, the ultraviolet rays contained in the sun rays originally contain UVA, UVB, and UVC, but UVC is remarkably absorbed in the ozone layer and the atmosphere, and the ultraviolet rays that reach the ground surface have a wavelength range of 200 to 380 nm. .

  The photoelectric conversion element shown in FIG. 1 will be further described.

  The substrate 1 is provided on the light incident direction side of the photoelectric conversion element 10, and from the viewpoint of imparting strength to the photoelectric conversion element and ensuring good photoelectric conversion efficiency, the substrate 1 is made of light transmissive materials such as glass and transparent resin material. It is made of material. In the present invention, it is preferable to provide a region 3 that absorbs light having a wavelength of 380 nm or less in the vicinity of the substrate 1 so that light that has passed through the region 3 provided in the vicinity of the substrate 1 reaches the photoelectric conversion layer 6. ing.

  The light transmittance of the substrate 1 is not particularly limited, but is preferably 10% or more, more preferably 50% or more, and particularly preferably 80% to 100%. Here, the “light transmittance” is a visible light wavelength measured by a method based on “Testing method of total light transmittance of plastic-transparent material” of JIS K 7361-1 (corresponding to ISO 13468-1). It means the “total light transmittance in a region”.

  The substrate 1 usable in the present invention can be appropriately selected from known ones, and examples thereof include transparent inorganic materials such as quartz and glass and the following known transparent resin materials.

  Specific examples of the transparent resin material include, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyimide (PI), polycarbonate (PC), polystyrene (PS), polypropylene (PP), Examples include polybutylene terephthalate (PBT), trimethylene terephthalate, polybutylene naphthalate, polyamideimide, cycloolefin polymer, and styrene butadiene copolymer. Among the transparent resin materials, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyimide (PI), and the like having a flexibility are commercially available to produce a flexible photoelectric conversion element. Is preferable.

  Further, the thickness of the substrate 1 can be appropriately set depending on the material and application. For example, when the substrate 1 is made of a hard material such as a transparent inorganic material such as glass, the average thickness is 0.1 mm to 1.5 mm. Preferably, 0.8 mm to 1.2 mm is more preferable. Moreover, when using a transparent resin material, it may be the same average thickness as the transparent inorganic material, but when using a transparent resin material having flexibility, 0.5 to 150 μm is preferable, and 10 to 75 μm is more preferable. preferable.

  Next, the first electrode 2 is disposed between the substrate 1 and the photoelectric conversion layer 6, and preferably 80% or more, more preferably 90% or more of light reaches the photoelectric conversion layer 6 in order to efficiently supply light. Those having a rate are used.

The first electrode 2 is formed of a known metal material or metal oxide, and specific examples of the metal material include platinum, gold, silver, copper, aluminum, etc., and have a shape that easily develops light transmittance. Silver is preferable because many processed products are supplied. For example, many grid pattern films having openings and films in which fine particles and nanowires are dispersed are supplied. Specific examples of the metal oxide include SnO ₂ , ZnO, CdO, CTO series, In ₂ O ₃ , CdIn ₂ O _4, etc., and the metal oxide is selected from Sn, Sb, F, and Al. Those doped with one or more atoms are preferably used. Among them, doped with Sn to _In 2 _{O 3,} called ITO, doped with Sb to SnO _2, conductive metal oxides doped with F to SnO ₂ is preferably called FTO, FTO in terms of heat resistance Is particularly preferred. Examples of the CTO-based metal oxide include CdSnO ₃ , Cd ₂ SnO ₄ , and CdSnO ₄ .

The first electrode 2 can also be provided on the substrate 1 described above, and the first electrode 2 provided on the substrate is called a conductive support, and the thickness of the conductive support is 0. The thickness is preferably 1 mm to 5 mm. It is preferable that the surface resistance of the conductive support is 50 [Omega / cm ² or less, 10 [Omega / cm ² or less being more preferred.

  Next, the photoelectric conversion layer 6 will be described. A photoelectric conversion element 10 shown in FIG. 1 has a photoelectric conversion layer 6 that is adjacent to the first electrode 2 described above and converts light energy such as sunlight into electric energy. The photoelectric conversion layer 6 contains a semiconductor to which a sensitizing dye is adsorbed, and exchanges electrons with the first electrode 2 where the light that has passed through the first electrode 2 is received. .

  Conversion of light energy into electric energy in the photoelectric conversion layer 6 is performed in the following procedure. First, light that has passed through the first electrode 2 enters the photoelectric conversion layer 6, and the light that has entered collides with the semiconductor. The light colliding with the semiconductor is diffusely reflected in an arbitrary direction and diffused in the photoelectric conversion layer 6, and the diffused light comes into contact with the sensitizing dye to generate electrons and holes, and the generated electrons are It moves toward the first electrode 2. With such a mechanism, the photoelectric conversion layer 6 converts light energy into electric energy.

  The thickness of the photoelectric conversion layer 6 is not particularly limited, but specifically, is preferably about 0.1 μm to 50 μm, more preferably about 0.5 μm to 25 μm, and particularly preferably about 1 μm to 10 μm. . In addition, the thickness of the photoelectric conversion layer 6 is substantially the same as the thickness of the contained semiconductor, and a semiconductor having a layered form is used from the viewpoint of realizing miniaturization of the element and reduction in manufacturing cost. Is preferred.

  The semiconductor 5 used for the photoelectric conversion layer 6 includes a simple substance such as silicon or germanium, Group 3 (Group 3A) to Group 5 (Group 5A), Group 13 (Group 3B) to Group 15 of the periodic table of elements. Compounds having atoms belonging to the group (Group 5B), metal chalcokeides, metal nitrides and the like can be used. Here, the metal chalcogenide is a compound composed of metal atoms and atoms belonging to Group 16 (Group 6B) of the periodic table of elements such as oxygen atoms and sulfur atoms called chalcogen elements. Metal sulfide, metal selenide, metal telluride and the like are applicable.

Specific examples of metal chalcogenides include the following.
(1) Metal oxides TiO, TiO ₂ , Ti ₂ O ₃ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O _5, etc. (2) Metal sulfides CdS, ZnS, PbS, Bi ₂ S ₃ , CuInS _2, etc. (3) metal selenides, metal tellurides CdSe, _PbSe, CuInSe 2, CdTe
Among the above metal carkenides, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, and PbS are preferably used, and among them, TiO ₂ and Nb ₂ O ₅ are more preferable, and dioxide dioxide Titanium TiO ₂ is particularly preferred. In addition to having good electron transport properties, titanium dioxide has high sensitivity to light, and titanium dioxide itself receives light to generate electrons directly. Preferred. In addition, since titanium dioxide has a stable crystal structure, even if light irradiation is performed in a harsh environment, deterioration with time hardly occurs, and predetermined performance can be stably expressed over a long period of time.

  By the way, there are anatase type and rutile type in the crystal structure of titanium dioxide, and semiconductor materials for photoelectric conversion elements are mainly those of anatase type crystal structure, those mainly of rutile type crystal structure, both Any of those based on the above mixture can be used. Among these, titanium dioxide having an anatase type crystal structure can perform efficient electron transport. When anatase type and rutile type are used in combination, the mixing ratio of the anatase type and rutile type is not particularly limited, and anatase type: rutile type = 95: 5 to 5:95. It is possible, and it is preferable to set it as 80: 20-20: 80.

Further, as a metal nitride that can be used for a semiconductor, for example, Ti ₃ N ₄ is representative, and a metal phosphorus compound such as GaP or InP or a compound such as GaAs can also be used as a semiconductor. is there.

A plurality of semiconductors used in the photoelectric conversion layer 6 can be used in combination with the semiconductor using the above compound alone. Specific examples in which a plurality of compounds are used in combination include, for example, those in which 20% by mass of Ti ₃ N ₄ is mixed with TiO ₂ , Chem. Soc. Chem. Commun. 15 (1999), there are ZnO and SnO ₂ composites. Further, when a metal oxide or metal sulfide and a compound other than the oxide or sulfide are used in combination, the content of the compound is preferably 30% by mass or less.

  Moreover, as the semiconductor used for the photoelectric conversion layer 6, it is possible to use a semiconductor that has been surface-treated with an organic base. The surface treatment of the semiconductor is mainly carried out by immersing the semiconductor in a liquid bath containing an organic base. When the organic base is liquid, it is used as it is, and when it is solid, it is dissolved in an organic solvent. Use the solution. Examples of the organic base used for the surface treatment include diarylamine, triarylamine, pyridine, 4-t-butylpyridine, polyvinylpyridine, quinoline, amidine and the like. Among these, pyridine, 4-t-butylpyridine Polyvinylpyridine is preferred.

  In addition, the semiconductor material preferably has a plurality of fine pores (pores) on the surface from the viewpoint of improving the photoelectric conversion efficiency by promoting the diffuse reflection and diffusion of the colliding light. Therefore, high photoelectric conversion efficiency can be expected. The pores of the semiconductor material can be defined by, for example, the ratio of the area of the pores per unit area of the surface of the semiconductor particles called porosity. In other words, the semiconductor material having an appropriate porosity promotes diffuse reflection and diffusion of light, and in addition, the sensitizing dye adsorbed on the outer surface of the semiconductor material and the inner surface of the pore as the surface area increases due to the pore. The adsorption area is also increased, and the photoelectric conversion efficiency can be further improved. The porosity of the semiconductor material is not particularly limited. For example, in the case of titanium dioxide, 5% to 90% is preferable, more preferably 15% to 80%, and particularly preferably 25% to 70%. is there.

  Further, the average particle diameter of the semiconductor 5 is not particularly limited, but is usually preferably 1 nm to 1 μm, and more preferably 5 nm to 50 nm. When the average particle size of the semiconductor material is within the above range, it becomes easier to improve the uniformity of the semiconductor material when the sol solution is formed. As the dye is adsorbed to the same level, it contributes to the improvement of power generation efficiency.

  Further, the semiconductor 5 has a structure in which a photosensitizing dye is adsorbed, but the adsorption formed between the semiconductor material and the photosensitizing dye is, for example, physical such as intermolecular attractive force or electrostatic attractive force. It is realized by a chemical bond such as a covalent bond or a coordinate bond. The photosensitizing dye generates electrons and holes by receiving light, and actually converts light energy into electric energy in the photoelectric conversion layer 6. That is, in the photoelectric conversion layer 6, the region where the photosensitizing dye is present functions as a light receiving region for generating electrons and holes. As described above, the sensitizing dye 4 is formed on the outer surface of the semiconductor 5. Adsorbed along the inner surface of the hole. The electrons generated by the sensitizing dye 4 move to the semiconductor 5 bonded to the sensitizing dye 4 and move from the semiconductor 5 toward the first electrode 2.

  The sensitizing dye 4 is carried on the semiconductor 5 by a sensitizing process by a known method, and is excited by light irradiation to emit electrons. In this invention, it is possible to use the well-known sensitizing dye which can be used for a photoelectric conversion element. Sensitizing dyes that can be used in the photoelectric conversion element include known organic pigments, carbon-based pigments, inorganic pigments, and organic or inorganic dyes.

First, examples of organic pigments for sensitizing dyes include phthalocyanine pigments, azo pigments, anthraquinone pigments, quinacridone pigments, and perylene pigments as shown below.
(1) Phthalocyanine pigments; phthalocyanine green, phthalocyanine blue, etc. (2) Azo pigments: Fast yellow, disazo yellow, condensed azo yellow, benzimidazolone yellow, dinitroaniline orange, benzimidazolone orange, toluidine red, permanent carmine, Permanent red, naphthol red, condensed azo red, benzimidazolone carmine, benzimidazolone brown, etc. (3) anthraquinone pigments; anthrapyrimidine yellow, anthraquinonyl red, etc. (4) quinacridone pigments; quinacridone magenta, quinacridone maroon, quinacridone scarlet (5) Perylene pigments such as perylene red and perylene maroon.

In addition to the above organic pigments, the following organic pigments can also be used. That is,
Azomethine pigments such as copper azomethine yellow, quinophthalone pigments such as quinophthalone yellow, isoindoline pigments such as isoindoline yellow, nitroso pigments such as nickel dioxime yellow, perinone pigments such as perinone orange, diketopyrrolopyrrole red Pyrrolopyrrole pigments such as dioxazine pigments such as dioxazine violet.

  Carbon-based pigments include, for example, carbon black, lamp black, furnace black, ivory black, graphite, fullerene and the like.

Furthermore, specific examples of dyes that can be used for the photosensitizing dye include, for example, RuL ₂ Cl ₂ , RuL ₂ (CN) ₂ , ruthenium 535-bisTBA (manufactured by Solaronics), [Ru ₂ (NCS) ₂ ] _2. There are metal complex dyes such as H ₂ O. Here, L in RuL ₂ Cl ₂ and RuL ₂ (CN) ₂ represents 2,2-bipyridine or a derivative thereof. In addition to the metal complex dyes, organic dyes such as cyan dyes and azo dyes, and organic dyes derived from natural products such as hibiscus dyes, blackberry dyes, raspberry dyes, pomegranate juice dyes, and chlorophyll dyes are used. It is also possible.

  A specific description of the sensitizing treatment of the semiconductor 5 with the sensitizing dye 4 will be described in the section “Preparation of Photoelectric Conversion Layer” described later.

  Next, the second electrode 8 will be described. The second electrode 8 is formed in a layer shape (flat plate shape) adjacent to the hole transport layer 7, and the average thickness is appropriately set depending on the material, use, etc., and is not particularly limited. The second electrode 8 can be formed using a known conductive material or semiconductive material. Examples of the conductive material include various ion conductive materials, metals such as aluminum, nickel, cobalt, platinum, silver, gold, copper, molybdenum, titanium, and tantalum, alloys containing these, and various carbons such as graphite. Materials and the like. Examples of the semiconductive material include p-type semiconductor materials such as triphenyldiamine (monomers, polymers, etc.), polyaniline, polypyrrole, polythiophene, phthalocyanine compounds (eg, copper phthalocyanine, etc.), and derivatives thereof. . The second electrode 8 can be formed by combining one or more of these conductive materials and semiconductive materials.

  The photoelectric conversion element 10 shown in FIG. 1 has a barrier layer 11 between the first electrode 2 and the photoelectric conversion layer 6, and the barrier layer 11 prevents the occurrence of a short circuit. When the barrier layer 11 is provided, the thickness thereof is, for example, about 0.01 μm to 10 μm and is formed using a known metal oxide such as zinc oxide (ZnO).

  Next, an example is given and demonstrated about the manufacturing method of the photoelectric conversion element which concerns on this invention. The photoelectric conversion element according to the present invention can be manufactured, for example, by the following procedures [1] to [6]. The method for producing the photoelectric conversion element according to the present invention is not limited to the one produced through the following steps, and can be produced by other known methods. In addition, in this invention, it is preferable to produce a photoelectric conversion element through the heat processing demonstrated by [6].

[1] Formation of the first electrode A known film-forming apparatus such as a pulsed laser vapor deposition method is prepared by preparing a glass substrate having a uniform thickness and having a light transmission property or a resin substrate having excellent heat resistance. Etc., the first electrode 2 is formed on the substrate. Examples of the organic material having excellent heat resistance include polyethylene naphthalate (PEN) resin and polyimide resin.

[2] Formation of Photoelectric Conversion Layer Next, the photoelectric conversion layer 6 is formed on the upper surface of the first electrode using a semiconductor material. For example, when the semiconductor is in the form of particles, the photoelectric conversion layer 6 can be formed by coating or spraying the semiconductor on the substrate on which the first electrode is formed. In the case of a film-like semiconductor, it can be formed by bonding the semiconductor to the substrate on which the first electrode is formed. One preferred embodiment for forming the photoelectric conversion layer 6 is a method of firing and forming semiconductor particles. When the photoelectric conversion layer 6 is formed by firing the semiconductor particles, the sensitization treatment performed on the semiconductor is preferably performed after the firing, and particularly preferably performed after the firing and before water is adsorbed to the semiconductor. Hereinafter, a method for forming the photoelectric conversion layer 6 by baking the semiconductor particles will be described.

A method of firing the semiconductor particles to form the photoelectric conversion layer 6 is performed, for example, through the following procedure. That is,
(1) Preparation of coating solution containing semiconductor particles (2) Application and baking treatment of coating solution containing semiconductor particles (3) Sensitizing dye adsorption treatment to semiconductor The following describes these.

(1) Preparation of coating solution containing semiconductor particles In this step, the coating solution is prepared by introducing and dispersing semiconductor particles in a known solvent. The concentration of the semiconductor particles in the coating solution is preferably, for example, from 0.1% by mass to 70% by mass, and more preferably from 0.1% by mass to 30% by mass. The semiconductor particles preferably have a small particle size, for example, those having an average primary particle size of 1 nm to 5000 nm are preferably used, and those having a particle size of 2 nm to 100 nm are more preferably used.

  The solvent for dispersing the semiconductor particles is not particularly limited as long as the semiconductor particles can be dispersed without aggregating the semiconductor particles. Water, a known organic solvent, or a mixture of water and an organic solvent is not limited. Is mentioned. Specific examples of the organic solvent include alcohols such as methanol and ethanol, ketones such as acetone, methyl ethyl ketone and acetylacetone, and hydrocarbons such as n-hexane and cyclohexane.

  In addition, known surfactants and viscosity modifiers can be added to the coating solution as necessary. Specific examples of viscosity modifiers include polyhydric alcohols such as polyethylene glycol. As mentioned.

(2) Application of coating liquid containing semiconductor particles and baking treatment In this step, the coating liquid formed by dispersing the above-described semiconductor particles in a solvent is applied to the substrate on which the first electrode is formed and dried. A layer of semiconductor particles is formed. Then, the semiconductor 5 is fixed in a layered manner on the substrate by performing a baking process in the air or in an inert gas atmosphere. The semiconductor 5 formed in this layer shape is also called a semiconductor layer. The layer of semiconductor particles formed on the substrate by coating is weak in bonding force with the support or bonding force between the semiconductor particles. As a result, the bond strength is improved and the layer becomes durable and strong. The thickness of the semiconductor layer formed by the baking treatment is preferably at least 10 nm or more, and more preferably from 500 nm to 30 μm.

  In addition, the semiconductor layer forms a strong porous structure by the baking treatment, and the photoelectric conversion efficiency is improved by making the hole transport material exist in the voids constituting the porous structure. In this way, the porous semiconductor layer has a larger actual surface area than the apparent surface area, so it is very effective in improving various performances including photoelectric conversion efficiency. is there. For example, the porosity of the semiconductor layer is preferably 1% to 90% by volume, more preferably 10% to 80% by volume, and particularly preferably 20% to 70% by volume. The void formed in the semiconductor layer has penetrability in the thickness direction of the layer, and the porosity can be measured by a known method. As a typical means for measuring the porosity, for example, there is a commercially available mercury porosimeter “Shimadzu Pore Sizer 9220 (manufactured by Shimadzu Corporation)”.

  In addition, the temperature during the baking treatment is preferably a temperature range lower than 1000 ° C., more preferably a temperature range of 200 ° C. to 800 ° C., from the viewpoint of forming a porous structure having the above porosity. A temperature range of 300 ° C. to 800 ° C. is particularly preferred. By the way, when forming a baked semiconductor layer on a resin substrate, it is not necessary to perform a baking treatment at 200 ° C. or higher. Instead, by applying a pressure treatment, the semiconductor particles can be fixed to each other or bonded to the substrate. Fixing is possible. In addition, it is possible to perform a baking process by heating only the semiconductor layer without heating the substrate using microwaves.

  Furthermore, in order to efficiently perform electron injection into the semiconductor layer by a sensitizing dye described later, it is possible to perform a plating process on the semiconductor layer formed by the baking process by a known chemical or electrochemical method. is there.

(3) Sensitizing dye adsorption to semiconductor 5 The sensitizing treatment to semiconductor 5 involves immersing a substrate provided with a photoelectric conversion layer (semiconductor layer) in which a semiconductor is formed in a layer form in a solution in which a sensitizing dye is dissolved. It is what you do. The total supported amount of the sensitizing dye 4 to the photoelectric conversion layer 6 is preferably from 0.01 to 100 mmole / ^{m 2,} more preferably 0.1 to 50 mmol / ^{m 2,} 0.5 to 20 mmol / ^{m 2} Particularly preferred.

  The sensitizing treatment can be performed by any of a method using a single type of sensitizing dye and a method using a combination of a plurality of types of sensitizing dyes. For example, a photoelectric conversion element for a solar cell can be converted into a wavelength capable of photoelectric conversion. In order to ensure a wide range, a method of using a plurality of dyes having different absorption wavelengths is preferable.

The solvent for dissolving the sensitizing dye may be any solvent that does not dissolve or react with the semiconductor while dissolving the sensitizing dye, and a known organic solvent can be used. Examples of such organic solvents include the following nitrile solvents, alcohol solvents, ketone solvents, ether solvents, halogenated hydrocarbon solvents, and the like. These solvents can be used alone or in combination.
(A) Nitrile solvents; acetonitrile and the like (b) Alcohol solvents; methanol, ethanol, n-propanol and the like (c) Ketone solvents; Acetone, methyl ethyl ketone and the like (d) Ether solvents; Diethyl ether, diisopropyl ether, tetrahydrofuran, (E) halogenated hydrocarbon solvents such as 1,4-dioxane; methylene chloride, 1,1,2-trichloroethane, etc. Among the above solvents, acetonitrile, acetonitrile / methanol mixed solvent, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran, Methylene chloride is preferred.

  The immersion time in the solution containing the sensitizing dye is, for example, 3 ° C. at a temperature of 25 ° C. in order to sufficiently sensitize the semiconductor by allowing the solution to penetrate deeply into the semiconductor layer and sufficiently adsorbing the semiconductor. The time is preferably 48 hours, more preferably 4 to 24 hours. Further, the solution can be heated as long as the sensitizing dye contained therein is not decomposed. For example, the temperature of the solution can be set to 25 ° C. to 80 ° C.

  The photoelectric conversion layer 6 can be manufactured by the above procedure.

[3] Formation of Hole Transport Layer In the present invention, the hole transport layer 7 containing a conductive polymer as a hole transport material can be formed by the above-described method. The layer 7 is formed so as to penetrate into the photoelectric conversion layer 6.

[4] Formation of Second Electrode The second electrode is formed on the upper surface of the hole transport layer. The second electrode can be formed by using a known method such as a vapor deposition method, a sputtering method, a printing method, or the like, for example, from a second electrode material made of gold or the like.

[5] Formation of UV-absorbing layer In the present invention, the UV-absorbing layer 3 that absorbs light having a wavelength of 380 nm or less is provided on the side on which light is incident on the photoelectric conversion layer 6. The “side” is the side on which the substrate 1 and the first electrode 2 are provided. As a specific method of providing the ultraviolet absorbing layer 3, for example, there is a method of providing a region that absorbs light having a wavelength of 380 nm or less in the substrate 1. That is, it can be formed by a method of sticking a commercially available ultraviolet absorbing film to the substrate 1 or a method of applying a commercially available ultraviolet absorbing paint to the substrate 1. Further, it is formed by applying a transparent resin solution such as a cellulose acetate resin containing a benzophenone compound, a benzotriazole compound, a benzoate compound, or a triazine compound having a property of absorbing ultraviolet rays to the substrate 1. It is also possible.

[6] Implementation of heat treatment As a preferred mode for producing the photoelectric conversion device according to the present invention, “at least a method for producing a photoelectric conversion device by performing a heat treatment after forming a photoelectric conversion layer and a hole transport layer”. ". The photoelectric conversion element manufactured by performing this heat treatment does not cause a decrease in photoelectric conversion efficiency over time, and makes it possible to stably maintain the photoelectric conversion efficiency over a long period of time.

  The reason why the photoelectric conversion element subjected to the heat treatment stably maintains the initial photoelectric conversion efficiency over a long period is not clear, but is considered as follows. That is, it is considered that the conductive polymer chains forming the hole transport layer form a denser arrangement state by the heat energy during the heat treatment. Since the conductive polymer chains are arranged in high density, the suppression of molecular motion of the conductive polymer chains is maintained even when the opportunity to receive sunlight is long, so the initial photoelectric conversion efficiency is long-term. It is thought that it is maintained stably over time. Moreover, it is thought that the fact that the strength of the hole transport layer is improved by increasing the density of the conductive polymer chain also contributes to the long-term stable maintenance of the photoelectric conversion efficiency.

  In addition, it is preferable that the process temperature at the time of performing the said heat processing shall be 70 to 150 degreeC, and the temperature range of 80 to 120 degreeC is especially preferable.

  Through the above steps, the photoelectric conversion element according to the present invention can be manufactured.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited only to a following example. In the following text, “part” represents “part by mass”.

1. 1. Production of “photoelectric conversion elements 1 to 35” and “comparative photoelectric conversion elements 1 to 7” 1-1. Production of “Photoelectric Conversion Element 1” “Photoelectric conversion element 1” having the configuration shown in FIG. 1 was produced by the following procedure.

(1) Preparation of substrate A commercially available soda glass substrate having a length of 30 mm, a width of 35 mm, and a thickness of 2.5 mm is prepared, and the substrate is immersed in a cleaning solution of 85 ° C. made of a mixed solution of sulfuric acid and hydrogen peroxide solution for cleaning. The surface was cleaned by performing the treatment.

(2) Formation of first electrode and barrier layer Using a known deposition apparatus, an FTO (fluorine-doped oxidation) having a length of 30 mm, a width of 35 mm, a thickness of 1 μm, and a sheet resistance of 20 Ω / □ is formed on the soda glass substrate. A first electrode made of tin) was formed. A solution prepared by dissolving 1.2 ml of tetrakisisoporopoxytitanium and 0.8 ml of acetylacetone in 18 ml of ethanol was dropped on the substrate on which the first electrode was formed, and after film formation by spin coating, heated at 450 ° C. for 8 minutes, A barrier layer made of titanium oxide having a thickness of 40 nm was formed on the first electrode.

(3) Formation of photoelectric conversion layer Next, a photoelectric conversion layer made of titanium oxide was formed on the upper surface of the barrier layer and the first electrode of the FTO thin film by the following procedure. That is,
First, an anatase-type titanium dioxide paste (average primary particle size 18 nm (microscope observation average), dispersion of ethyl cellulose) is applied onto the soda glass substrate on which the barrier layer and the first electrode are formed so that the coating area becomes 25 mm ² . It was applied by screen printing. After the coating, a baking treatment was performed at 200 ° C. for 10 minutes and at 500 ° C. for 15 minutes to form a titanium dioxide thin film having a thickness of 2.5 μm. The titanium dioxide thin film had a porous structure having voids.

Next, as a sensitizing dye, a D149 dye (manufactured by Mitsubishi Paper Industries Co., Ltd.) having the following structure is dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1 to give a solution of 5 × 10 ⁻⁴ mol / liter. Was prepared.

  The glass substrate coated with titanium dioxide and sintered was immersed in the solution at room temperature for 3 hours to adsorb the dye and subjected to sensitization treatment. In this way, a photoelectric conversion layer was formed.

(4) Formation of hole transport layer A glass substrate on which the photoelectric conversion layer is formed,
M1-1 0.01 mol / L Li [(CF ₃ SO ₂ ) ₂ N] It is insoluble in a solvent on the photoelectric conversion layer by dipping in a 0.1 mol / L acetonitrile solution and conducting electrolytic polymerization. A hole transport layer containing a conductive polymer was formed.

In the electrolytic polymerization, the working electrode was the first electrode, the counter electrode was a platinum wire, the reference electrode was Ag / Ag ⁺ (AgNO ₃ 0.01 mol), and the holding voltage was −0.16V. The voltage is held for 30 minutes while irradiating light from the photoelectric conversion layer direction (using a xenon lamp as a light source, cutting light having a light intensity of 22 mW / cm ² and a wavelength of 430 nm or less).

After forming the hole transport layer by the above procedure, the glass substrate was washed with acetonitrile and dried. after that,
Li [(CF ₃ SO ₂ ) ₂ N] 1.5 × 10 ⁻² mol / L t-Butylpyridine 5 × 10 ⁻² mol / L An acetonitrile solution containing 10 minutes of immersion treatment and then air-dried A hole transport layer was prepared.

(5) Formation of 2nd electrode and ultraviolet absorption layer Next, gold was vapor-deposited by the vacuum evaporation method on the said positive hole transport layer so that it might become thickness 60nm, and the 2nd electrode was formed. Further, a commercially available ultraviolet absorbing film “Scotch Tent Window Film RE87CLIS (manufactured by Sumitomo 3M Limited)” (UV transmittance 0% as measured by JIS A5759) is pasted on the surface of the glass substrate where the first electrode is not formed. Thus, an ultraviolet absorbing layer was formed. By the above procedure, “photoelectric conversion element 1” having the structure shown in FIG. 1 was produced.

1-2. Preparation of “Photoelectric Conversion Elements 2 to 35” (1) Preparation of “Photoelectric Conversion Elements 2 to 27” The compound “M1-1” used for forming the hole transport layer in the preparation of the “photoelectric conversion elements 1”. "Photoelectric conversion elements 2 to 27" were prepared in the same procedure except that a hole transport layer was formed using the compounds shown in Table 1 below.

(2) Production of “photoelectric conversion elements 28 and 29” In addition, in the production of “photoelectric conversion element 3”, a commercially available fluororesin coating material having an ultraviolet cut function without attaching an ultraviolet absorbing film to the glass substrate “ “Obligard (manufactured by AGC Co-Tech Co., Ltd.)” was applied to form an ultraviolet absorbing layer. Otherwise, the same procedure was followed to produce “photoelectric conversion element 28”. In addition, in the production of the “photoelectric conversion element 1”, a commercially available ultraviolet cut glass “UV veil (manufactured by Asahi Glass Co., Ltd.)” was used instead of the above-mentioned soda glass base, and the other procedures were the same as “Photoelectric conversion element 1”. A conversion element 29 "was produced.

(3) Production of “photoelectric conversion elements 30 to 35” In addition, in the production of the “photoelectric conversion element 3”, an ultraviolet absorbing film was not applied to the glass substrate, and a coating solution containing the following compound was applied to the relevant part. And dried to provide an ultraviolet absorbing layer having the same thickness as the ultraviolet absorbing film. Otherwise, the same procedure was followed to produce “photoelectric conversion element 30” having an ultraviolet absorption layer containing 2-hydroxy-4-methoxybenzophenone, which is one of the benzophenone compounds, in the acetate film.

Coating liquid composition Cellulose triacetate (oxidation degree 61.0%) 100 parts by weight Triphenyl phosphate 12 parts by weight 2-hydroxy-4-methoxybenzophenone 1 part by weight Methylene chloride 430 parts by weight Methanol 90 parts by weight It is formed by putting it into a closed container, keeping it at 80 ° C. under pressure, completely dissolving it with stirring, and then performing a filtration treatment.

  Further, in the production of the “photoelectric conversion element 30”, the 2-hydroxy-4-methoxybenzophenone used in the production of the coating solution was changed to 2- (2H-benzotriazol-2-yl) -4-t-butylphenol. Thus, a coating solution was prepared. Others took the same procedure, and provided an ultraviolet absorption layer containing 2- (2H-benzotriazol-2-yl) -4-t-butylphenol, which is one of the benzotriazole compounds, in the acetate film. Element 31 "was produced.

  Further, in the production of the “photoelectric conversion element 30”, the 2-hydroxy-4-methoxybenzophenone used in the production of the coating solution was replaced with 2,4-di-t-butylphenyl-3,5-di-t-butyl. A coating solution was prepared by changing to -4-hydroxybenzoate. Others adopt the same procedure, and an ultraviolet absorbing layer containing 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, which is one of benzoate compounds, in an acetate film A “photoelectric conversion element 32” provided with the above was produced.

  Further, in the production of the “photoelectric conversion element 30”, 2-hydroxy-4-methoxybenzophenone used in the production of the coating solution was replaced with 2- [4,6-diphenyl-1,3,5-triazin-2-yl. ] -5-[(hexyl) oxy] phenol was used to prepare a coating solution. Otherwise, the same procedure was followed, and 2- [4,6-diphenyl-1,3,5-triazin-2-yl] -5-[(hexyl) oxy] phenol, one of the triazine compounds in the acetate film "Photoelectric conversion element 33" provided with an ultraviolet absorbing layer containing benzene was produced.

  In addition, instead of 2-hydroxy-4-methoxybenzophenone used in the preparation of the coating solution in the preparation of the “photoelectric conversion element 30”, commercially available zinc oxide particles “FINEX-30S-LP2 (Sakai Chemical Industry Co., Ltd.) ))) ”Was used to prepare a coating solution. Otherwise, the same procedure was followed to produce “photoelectric conversion element 34” in which an ultraviolet absorption layer containing zinc oxide was provided in an acetate film.

  Further, in the production of the “photoelectric conversion element 30”, instead of 2-hydroxy-4-methoxybenzophenone used in the production of the coating solution, commercially available titanium oxide particles “STR-60C-LP (Sakai Chemical Industry Co., Ltd.) ))) ”Was used to prepare a coating solution. Otherwise, the same procedure was followed to produce “photoelectric conversion element 35” in which an ultraviolet absorption layer containing titanium oxide was provided in the acetate film.

1-3. Production of “Comparative Photoelectric Conversion Elements 1 to 7” (1) Production of “Comparative Photoelectric Conversion Elements 1 to 3” In the production of the “photoelectric conversion element 1”, the hole transport layer was formed by the following procedure. Otherwise, the same procedure was taken to produce “Comparative Photoelectric Conversion Element 1”. That is, the “aromatic amine compound A2” shown below is used as the hole transport material, and this is dissolved in tetrahydrofuran to prepare a coating solution for forming a hole transport layer. Next, the hole transport layer forming coating solution is applied to the upper surface of the photoelectric conversion layer by the spin coating method and subjected to vacuum drying for 10 minutes to remove tetrahydrofuran and form a hole transport layer. To do. The coating liquid for forming the hole transport layer was applied by setting the spin coating speed to 500 rpm.

  In addition, the “aromatic amine compound A2” used when preparing the coating liquid for forming the hole transport layer in the production of the “comparative photoelectric conversion element 1” is changed to the “aromatic amine compound A22” shown below. Otherwise, the same procedure was followed to produce “Comparative Photoelectric Conversion Element 2”. Furthermore, the same procedure was followed except that the “aromatic amine compound A2” used in preparing the hole transport layer forming coating solution was changed to the “aromatic amine compound A26” shown below. 3 "was produced. “Compound A26” is called 2,2 ′, 7,7′-tetrakis (N, N-di-p-methoxyphenylamine) 9,9′-spirobifluorene.

(2) Production of “Comparative Photoelectric Conversion Element 4” In the production of the “photoelectric conversion element 1”, a compound T1 shown below was used instead of the compound “M1-1” used in forming the hole transport layer. “Comparative photoelectric conversion element 4 for comparison” was produced in the same procedure except that the hole transport layer was formed by using it. The hole transport layer of “Comparative Photoelectric Conversion Element 4” is obtained by polymerizing Compound T1 and containing a polymer having the following structure.

(3) Production of “Comparative Photoelectric Conversion Elements 5-7” When producing the “photoelectric conversion elements 1, 10, 19”, the “comparison” was performed in the same procedure except that the ultraviolet absorbing film was not attached to the glass substrate. Photoelectric conversion elements 5 to 7 ”were prepared.

  By the above procedure, “photoelectric conversion elements 1 to 35” and “comparative photoelectric conversion elements 1 to 7” were produced. Note that. Table 1 below shows the compound for hole transport material and the method for forming the ultraviolet absorbing layer used when the above photoelectric conversion elements and comparative photoelectric conversion elements were prepared.

2. Evaluation Experiment With respect to “photoelectric conversion elements 1 to 35” and “comparative photoelectric conversion elements 1 to 7” produced by the above procedure, the stability maintaining performance of photoelectric conversion efficiency was evaluated as follows. That is, the photoelectric conversion efficiency η of each photoelectric conversion element is measured and calculated by the following method. Next, each photoelectric conversion element is heated to 85 ° C., placed in an oven, and left to stand for 5 hours for heat treatment. Then, the photoelectric conversion efficiency η ′ of each photoelectric conversion element after the heat treatment is measured and calculated, and the reduction rate of the photoelectric conversion efficiency η before and after the heat treatment is calculated and evaluated.

  Here, the photoelectric conversion efficiency η was measured before and after the heat treatment according to the above procedure, and the reduction rate of the photoelectric conversion efficiency η was calculated as “Examples 1 to 33” and “Comparative Examples 1 to 7”. Moreover, what carried out the process at the heat processing temperature of 70 degreeC, 120 degreeC, 150 degreeC, and 170 degreeC using the "photoelectric conversion element 2" was set as "Examples 34-37."

The photoelectric conversion efficiency η and η ′ of each photoelectric conversion element is measured and calculated according to the following procedure. That is,
Each photoelectric conversion element is irradiated with pseudo-sunlight with an irradiation intensity of 100 mW / cm ² formed by a commercially available solar simulator “WXS-85-H (manufactured by Wacom Denso Co., Ltd.)” in a room temperature environment (temperature 20 ° C.). . The simulated sunlight is formed by passing xenon lamp light through an AM filter (AM1.5) by the solar simulator.

  Here, the current-voltage characteristic of each photoelectric conversion element at the time of the artificial sunlight irradiation was measured using a commercially available IV tester, and the shape was determined based on the short-circuit current value Isc, the open-circuit voltage Voc, and the current-voltage characteristic graph. The coefficient FF is calculated. The photoelectric conversion efficiency η is calculated by substituting these values into the calculation formula described later. Note that the heat treatment is performed in a dark place in the oven.

  The “open circuit voltage Voc” is a voltage value when a current is not applied by applying a voltage load to the photoelectric conversion element, and the “short-circuit current value Isc” is a voltage load applied to the photoelectric conversion element. It is the value of the current that flows when it is not applied. Further, the “shape factor FF” is a numerical value indicating the locus shown in the voltage-current characteristic graph obtained when measuring the photoelectric conversion efficiency described later. The irradiation intensity Pmax is the short-circuit current value Isc and the open-circuit voltage. It is a value obtained by dividing by the product of Voc. FIG. 2 shows an example of a locus of the voltage-current characteristic graph when the shape factor FF is calculated and when the shape factor FF is 1.00 and less than 1.00.

The photoelectric conversion efficiency η is calculated from the following formula. That is, assuming that the irradiation intensity Pmax, the short-circuit current of each photoelectric conversion element is Isc (mA / cm ² ), the open circuit voltage is Voc (V), and the shape factor is FF, the photoelectric conversion efficiency η (%) is calculated from the following equation. The That is,
η (%) = [(Isc × Voc × FF) / Pmax] × 100
It becomes. Similarly, the photoelectric conversion efficiency η ′ after the heat treatment is calculated from the above formula.

In this evaluation, simulated solar light with an irradiation intensity Pmax of 100 mW / cm ² is irradiated from the solar simulator.

And the reduction | decrease rate (DELTA) (eta) (%) of the photoelectric conversion efficiency before and behind heat processing is computed from a following formula. That is,
Δη (%) = [(η−η ′) / η] × 100
In this evaluation, the photoelectric conversion efficiency η before the heat treatment and the photoelectric conversion efficiency η ′ after the heat treatment are both 4.00% or more, and the decrease rate Δη of the photoelectric conversion efficiency is 0.50% or less. Things were accepted. The above results are shown in Table 2 below.

  As shown in Table 2, “Examples 1 to 35” in which a photoelectric conversion element using a conductive polymer as a hole transport material and having a light absorption region with a wavelength of 380 nm or less was evaluated, all had high photoelectric conversion efficiency. It was confirmed that it had. In particular, it has been confirmed that those using polythiophenes formed by polymerizing a compound having bulky side chains as a hole transport material exhibit particularly high photoelectric conversion efficiency. Further, it was confirmed that high photoelectric conversion efficiency was exhibited even after the heat treatment at 85 ° C., and the photoelectric conversion efficiency was stably maintained at a high level. Furthermore, from “Examples 36 to 39”, it was confirmed that the photoelectric conversion efficiency was stably maintained at a high level by carrying out the heat treatment.

  On the other hand, “Comparative Examples 1 to 3” using a solid hole transport material having a molecular weight smaller than that of the hole transport material defined in the present invention can obtain good photoelectric conversion efficiency in the initial stage, but after the heat treatment, Conversion efficiency was greatly reduced. In addition, “Comparative Example 4” in which polythiophene having no structure defined in the present invention was used as the hole transport material had significantly lower photoelectric conversion efficiency than “Examples 1 to 39”. Furthermore, “Comparative Examples 5 to 7” having no ultraviolet absorbing layer could not obtain the photoelectric conversion efficiency of the level obtained in “Examples 1, 10, and 19” using the same hole transport material. .

DESCRIPTION OF SYMBOLS 1 Base | substrate 2 1st electrode 3 Ultraviolet absorption layer (area | region which absorbs light with a wavelength of 380 nm or less)
4 Semiconductor 5 Sensitizing dye 6 Photoelectric conversion layer 7 Hole transporting layer 8 Second electrode 9 Partition 10 Photoelectric conversion element

Claims (13)

A photoelectric conversion element having at least a substrate, a first electrode, a semiconductor and a photoelectric conversion layer containing a sensitizing dye, a hole transport layer containing a solid hole transport material, and a second electrode,
While having a region that absorbs light of a wavelength of 380 nm or less from the surface on which light is incident to the electrode located on the surface side,
The solid hole transport material contained in the hole transport layer is a conductive polymer formed by polymerizing a compound having a structure represented by any one of the following general formulas (1) to (3). The photoelectric conversion element characterized by the above-mentioned.

(In the formula, R _{1 to} R ₄ represent any one of a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, and an aryl group, and R _{1 to} R ₄ are the same or different. May be.)

(In the formula, R ₅ represents any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, n represents an integer of 1 or 2, and m represents an integer of 0 to 2n + 4.)

(In the formula, R _{6 to} R ₉ represent any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, and R _{6 to} R ₉ may be the same or different. .) In the compound having the structure represented by the general formula (1), at least one of R _{1 to} R ₄ is an alkyl group or cycloalkyl group having 6 to 14 carbon atoms, or an aryl group having 6 or more carbon atoms. Any of alkyl groups having an oxyethylene group,
R ₅ in the compound having the structure represented by the general formula (2) is either an aryl group having 6 or more carbon atoms or an alkyl group having an oxyethylene group, and the value of n is 1. ,
An alkyl having at least one of R _{6 to} R ₉ in the compound having the structure represented by the general formula (3) having an alkyl group having 6 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an oxyethylene group The photoelectric conversion element according to claim 1, wherein the photoelectric conversion element is any one of groups. The photoelectric conversion element is
3. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion element is manufactured through a step of performing a heat treatment after forming the photoelectric conversion layer and the hole transport layer.   The photoelectric conversion element according to claim 3, wherein a treatment temperature of the heat treatment performed after forming the photoelectric conversion layer and the hole transport layer is 70 ° C. or more and 150 ° C. or less.   The photoelectric conversion element according to claim 1, wherein the region that absorbs light having a wavelength of 380 nm or less is provided on the base. The region that absorbs light having a wavelength of 380 nm or less is:
6. The photoelectric conversion device according to claim 1, comprising any one of a benzophenone compound, a benzotriazole compound, a benzoate compound, and a triazine compound. The region that absorbs light having a wavelength of 380 nm or less is:
The photoelectric conversion element according to any one of claims 1 to 5, which contains either zinc oxide or titanium oxide.   The photoelectric conversion element according to claim 1, wherein the photoelectric conversion layer contains titanium oxide having a porous structure. At least a first electrode, a photoelectric conversion layer containing a semiconductor and a sensitizing dye, a hole transport layer containing a solid hole transport material, a second electrode, and a region that absorbs light having a wavelength of 380 nm or less on the substrate A process for producing a photoelectric conversion element comprising:
The manufacturing method of the photoelectric conversion element is at least:
A region for absorbing light having a wavelength of 380 nm or less is provided from the surface on which light is incident to the electrode located on the surface side, and
A method for producing a photoelectric conversion element comprising a step of polymerizing a compound having a structure represented by any one of the following general formulas (1) to (3) to form a hole transport layer.

(In the formula, R _{1 to} R ₄ represent any one of a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, and an aryl group, and R _{1 to} R ₄ are the same or different. May be.)

(In the formula, R ₅ represents any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, n represents an integer of 1 or 2, and m represents an integer of 0 to 2n + 4.)

(In the formula, R _{6 to} R ₉ represent any one of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and an aryl group, and R _{6 to} R ₉ may be the same or different. .) In the compound having the structure represented by the general formula (1), at least one of R _{1 to} R ₄ is an alkyl group or cycloalkyl group having 6 to 14 carbon atoms, or an aryl group having 6 or more carbon atoms. Any of alkyl groups having an oxyethylene group,
R ₅ in the compound having the structure represented by the general formula (2) is either an aryl group having 6 or more carbon atoms or an alkyl group having an oxyethylene group, and the value of n is 1. ,
An alkyl having at least one of R _{6 to} R ₉ in the compound having the structure represented by the general formula (3) having an alkyl group having 6 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an oxyethylene group The method for producing a photoelectric conversion element according to claim 9, wherein the method is any one of groups.   11. The photoelectric conversion element according to claim 9, wherein the method for manufacturing the photoelectric conversion element includes a step of performing a heat treatment after forming the photoelectric conversion layer and the hole transport layer. Manufacturing method.   The method for producing a photoelectric conversion element according to claim 11, wherein a treatment temperature of the heat treatment performed after forming the photoelectric conversion layer and the hole transport layer is 70 ° C. or more and 150 ° C. or less.   It has the photoelectric conversion element manufactured by the manufacturing method of the photoelectric conversion element of any one of Claims 1-8, or the photoelectric conversion element of any one of Claims 9-12, It is characterized by the above-mentioned. Solar cell.

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