WO2016021308A1

WO2016021308A1 - Photoelectric conversion layer and photoelectric conversion element provided with same

Info

Publication number: WO2016021308A1
Application number: PCT/JP2015/067699
Authority: WO
Inventors: 真実櫻井; 和寿福井
Original assignee: 株式会社ダイセル
Priority date: 2014-08-06
Filing date: 2015-06-19
Publication date: 2016-02-11
Also published as: TW201606827A; JP2016039212A

Abstract

A multilayer photoelectric conversion body, wherein a plurality of photoelectric conversion layers having different absorption wavelengths are laminated, is formed by sequentially coating a conductive substrate with a plurality of coating compositions, each of which contains a semiconductor (for example, titanium oxide particles) and an ionic polymer (for example, a fluorine-based resin having a sulfo group), without sintering the semiconductor, while having the coating compositions respectively contain a plurality of dyes having different absorption wavelength ranges or absorption peak wavelengths. This photoelectric conversion element is capable of efficient photoelectric conversion by means of a simple structure.

Description

Photoelectric conversion layer and photoelectric conversion element provided with the same

The present invention relates to a stacked photoelectric conversion layer and a photoelectric conversion element (a solar cell (particularly, a dye-sensitized solar cell)) including the photoelectric conversion layer.

Solar cells are attracting attention as clean energy with a low environmental impact, and solar cells using silicon (such as crystalline silicon) are widely used. However, since high-purity silicon is used, the power generation cost is high, and the conversion efficiency for faint light such as indoors is small.

Dye-sensitized solar cells are attracting attention as solar cells that can be manufactured at low cost. In a dye-sensitized solar cell, a photoelectrode is formed by adsorbing a sensitizing dye to a metal oxide semiconductor (such as titanium oxide).

Since photoelectric conversion in such a dye-sensitized solar cell occurs at the contact interface between the metal oxide semiconductor and the sensitizing dye, a metal oxide semiconductor having a large surface area (for example, nano-sized semiconductor) is used for the purpose of increasing the conversion efficiency. A metal oxide semiconductor) is used for the electrode, and the effective area is made larger than the apparent area. However, even if the metal oxide nanoparticles are simply applied to the substrate, they are peeled off from the substrate and do not function as electrodes, and the electrical resistance between the particles is large. Therefore, after applying the metal oxide nanoparticles, heat treatment is performed at a high temperature (about 500 ° C.) to sinter the metal oxide nanoparticles, and the sintered layer is immersed in a solution containing the dye to adsorb the dye. It is necessary to form a photoelectric conversion layer and avoid thermal decomposition of the dye. Such a method is a complicated process including a sintering process, and causes an increase in manufacturing cost. Furthermore, since it is necessary to expose the substrate to a high temperature during the sintering process, the substrate is limited to an inorganic material such as glass, and a flexible dye-sensitized solar cell using a plastic substrate cannot be produced. Moreover, since it is limited by the absorption wavelength region of the dye, it cannot be efficiently absorbed to a long wavelength region with a single dye, incident light utilization efficiency is low, and photoelectric conversion efficiency is low.

A tandem photoelectric conversion element using a plurality of dyes has been proposed in order to avoid thermal decomposition of the dyes and to effectively use incident light for photoelectric conversion. For example, in Japanese Patent Application Laid-Open No. 2008-34258 (Patent Document 1), a first photoelectric conversion cell including a first photoelectrode in which a first dye is adsorbed to a first porous semiconductor, and a second dye is a second porous material. A second photoelectric conversion cell having a second photoelectrode adsorbed on a crystalline semiconductor is stacked in a direction intersecting the incident light incident direction, and the first counter electrode and the second transparent conductive layer are connected in series. A tandem dye-sensitized photoelectric conversion element is described. Also in this document, the coating film of titanium oxide is baked to form the first porous semiconductor and the second porous semiconductor, respectively, and the first dye and the second dye are adsorbed respectively. This document also shows a single-layer photoelectrode in which a plurality of dyes are mixed and adsorbed, or a multi-layer photoelectrode in which a plurality of dyes are adsorbed in each region, but details thereof are not described.

Japanese Patent Laid-Open No. 2012-74365 (Patent Document 2) discloses a first photovoltaic cell (PV) cell in which a cathode and an anode are disposed via a first dye layer, and a second dye layer. The second PV cell in which the cathode and the anode are disposed, the first PV cell and the second PV cell are bonded together, and the first PV cell and the second PV cell are electrically connected to each other. A tandem dye-sensitized solar cell (DSC) with a first transparent conductive adhesive layer for series connection is described.

In these documents, since the first photoelectric conversion cell and the second photoelectric conversion cell are respectively produced and the first and second photoelectric conversion cells are stacked, incident light can be effectively photoelectrically converted. However, each photoelectric conversion cell includes a transparent support having a transparent conductive layer, a photoelectrode layer formed on the transparent conductive layer, a counter electrode facing the photoelectrode layer, a photoelectrode layer and a counter electrode. And an electrolytic solution filled in between. In addition, it is necessary to stack such two photoelectric conversion cells and to electrically connect the two photoelectric conversion cells. This complicates the structure of the tandem dye-sensitized solar cell. In addition, it is necessary to use at least one more expensive conductive transparent substrate, resulting in high cost. Furthermore, in the central part (light transmission part) of the photoelectric conversion cell, the electrode substrate and the electrolyte interposed between the pair of photoelectrode layers and the counter electrode absorb or scatter incident light, resulting in loss of light absorption. The photoelectric conversion efficiency cannot be greatly improved.

It is also known that two dyes are diffused into a bilayer of a sintered titanium oxide porous layer. However, this method still requires a sintering operation and a dye diffusing operation, and two dyes are mixed in the boundary region, so that a photoelectric conversion layer cannot be formed efficiently.

International Publication WO 2014/017536 (Patent Document 3) discloses a photoelectric conversion layer containing a semiconductor, an ionic polymer, and a dye, wherein the proportion of the ionic polymer is 0.1 to 30 parts by weight with respect to 1 part by weight of the semiconductor. It is described that the composition is applied to a conductive substrate and a photoelectric conversion layer is formed without sintering the semiconductor. This document also describes that the photoelectric conversion layer can be formed with high adhesion to the conductive substrate. However, this photoelectric conversion layer still has insufficient photoelectric conversion efficiency of incident light.

JP 2008-34258 A ([0019] [0020] [0022] [0078] to [0081] FIGS. 1 to 3) JP 2012-74365 A (Claims) WO 2014/017536 (Claims 14 and 17, [0091])

Accordingly, an object of the present invention is to provide a photoelectric conversion layer or a photoelectric conversion body (photoelectrode layer) capable of efficiently photoelectrically converting incident light with a simple structure, and a photoelectric conversion element (a dye-sensitized solar cell) including the photoelectric conversion layer. Etc.).

Another object of the present invention is to provide a photoelectric conversion layer (or a photoelectric conversion body) having different absorption wavelength ranges and high photoelectric conversion efficiency, and a photoelectric conversion element including the photoelectric conversion layer.

Still another object of the present invention is to provide a photoelectric conversion layer (or photoelectric conversion body) that has excellent durability without sintering and can maintain high photoelectric conversion characteristics over a long period of time and has high adhesion to a substrate. And a photoelectric conversion element including the photoelectric conversion layer.

Another object of the present invention is to provide a photoelectric conversion layer (or a photoelectrode layer) useful for forming a dye-sensitized solar cell and a photoelectric conversion element including the photoelectric conversion layer.

Yet another object of the present invention is to provide a coating composition useful for forming the photoelectric conversion layer (or photoelectric conversion body) and a method for easily and efficiently forming the photoelectric conversion layer (or photoelectric conversion body). There is to do.

As a result of intensive studies to solve the above problems, the present inventors have found that a semiconductor (such as titanium oxide), an ionic binder (for example, an ionic polymer such as a strongly acidic ion exchange resin), and a dye (sensitizing dye). In a plurality of coating compositions (coating agent or ink), a plurality of dyes having different absorption wavelength ranges or absorption peak wavelengths are contained in the coating composition, and the plurality of coating compositions are sequentially applied to the conductive substrate. Thus, when a stacked photoelectric conversion body is formed, it has been found that incident light can be efficiently photoelectrically converted, and the present invention has been completed.

That is, the laminated photoelectric conversion body (laminated body) of the present invention has a laminated structure in which a photoelectric conversion layer containing a semiconductor, an ionic binder, and a dye is laminated. A conversion layer (dye-sensitized photoelectric conversion layer) is laminated. And the absorption wavelength range or absorption peak wavelength of the pigment | dye contained in each photoelectric converting layer differs. That is, a plurality of photoelectric conversion layers (for example, adjacent photoelectric conversion layers) contain dyes having absorption wavelength ranges or absorption peak wavelengths different from each other. In the laminated photoelectric conversion body of the present invention, for example, the adjacent photoelectric conversion layer can also be referred to as a stacked photoelectric conversion layer containing dyes having different absorption peak wavelengths or absorption wavelength ranges, and a stacked photoelectric conversion containing two kinds of dyes. In the layer, a photoelectric conversion layer containing a first dye and a photoelectric conversion layer containing a second dye are stacked. Note that the photoelectric conversion layer and the stacked photoelectric conversion body are usually formed on a conductive substrate.

In the laminated photoelectric conversion body, the dye contained in the incident side (light receiving side) photoelectric conversion layer has an absorption peak wavelength in a shorter wavelength region than the absorption peak wavelength of the dye contained in the transmission side photoelectric conversion layer. Also good. For example, a photoelectric conversion layer (dye-sensitized photoelectric conversion layer) containing a dye capable of absorbing a short wavelength region (for example, a short wavelength region in the visible light region) is formed on the light receiving side, and the side opposite to the light receiving side (transmission side) ) May be formed with a photoelectric conversion layer (a dye-sensitized photoelectric conversion layer) containing a dye capable of absorbing a long wavelength region (for example, a long wavelength region in the visible light region).

Further, a plurality of photoelectric conversion layers may be formed without being sintered, and the total thickness of the plurality of photoelectric conversion layers may be about 0.1 to 100 μm. The ratio between the thickness Tr of the photoelectric conversion layer and the thickness Tt of the photoelectric conversion layer on the transmission side may be about Tr / Tt = 10/90 to 80/20 (for example, 30/70 to 80/20). .

The photoelectric conversion layer on the light receiving side contains a first dye having an absorption peak wavelength at 300 to 650 nm (for example, 300 to 600 nm), and the photoelectric conversion layer on the opposite side (transmission side) from the light receiving side is 550 to 800 nm. A second dye having an absorption peak wavelength (for example, 600 to 800 nm) may be contained. The absorption peak wavelengths of the plurality of dyes (for example, the absorption peak wavelengths of the first dye and the second dye) may be close to each other, but the absorption peak wavelength of the first dye is usually the second. It may be shorter than the absorption peak wavelength of the dye by 10 nm or more, and the absorption peak wavelengths of the plurality of dyes are separated by, for example, about 10 to 200 nm (for example, 20 to 200 nm, preferably 30 to 150 nm).

In the photoelectric conversion layer, the semiconductor may include at least one selected from titanium oxide nanoparticles, zinc oxide nanoparticles, and tin oxide nanoparticles, and the ionic polymer includes a fluorine-containing resin having a sulfo group. Also good. The proportion of the ionic polymer may be about 1 to 100 parts by weight (for example, 5 to 50 parts by weight) with respect to 100 parts by weight of the semiconductor.

The present invention is a set of a coating composition (or ink) for forming a plurality of photoelectric conversion layers on a conductive substrate, which contains a semiconductor, an ionic polymer, and a dye, and the plurality of coating compositions are A set of a plurality of coating compositions each containing a dye having a different absorption wavelength range or absorption peak wavelength is also included.

The present invention also includes a method for producing the laminated photoelectric converter. In this method, a plurality of coating compositions (or inks) containing a semiconductor, an ionic polymer, and a pigment are applied to a conductive substrate. The photoelectric conversion layer is formed (usually, the photoelectric conversion layer is formed without sintering). The absorption wavelength range or the absorption peak wavelength of the dye contained in each coating agent is different from each other. That is, a plurality of dyes having different absorption wavelength ranges or absorption peak wavelengths are respectively contained in the coating composition (or ink) (or a coating composition is prepared for each dye having a different absorption wavelength range or absorption peak wavelength). Then, a plurality of coating compositions (or inks) are sequentially coated and laminated on a conductive substrate, and a laminated photoelectric conversion body is formed without sintering.

Furthermore, the present invention also includes a photoelectric conversion element provided with the laminated photoelectric converter (laminated body). This photoelectric conversion element includes the laminated photoelectric conversion body formed on a conductive substrate as an electrode (photoelectrode), a counter electrode (another electrode) disposed opposite to the electrode, and an interval between these electrodes And an electrolyte phase (or electrolyte layer) sealed in the substrate, and the photoelectric conversion element may form a dye-sensitized solar cell.

The present invention comprises a photoelectric conversion layer formed on a conductive substrate as an electrode, a counter electrode disposed opposite to the electrode, and an electrolyte phase (or electrolyte layer) sealed between these electrodes. The manufacturing method of the provided photoelectric conversion element is also included. In this method, a plurality of coating compositions containing a semiconductor, an ionic polymer, and a pigment are sequentially coated on a conductive substrate and laminated, and a plurality of photoelectric conversion layers are laminated without sintering. A step of forming a laminated photoelectric converter, and the absorption wavelength range or the absorption peak wavelength of the dyes contained in the respective coating agents are different from each other. That is, a process in which a plurality of dyes having different absorption wavelength ranges or absorption peak wavelengths are contained in the coating composition, and a plurality of coating compositions containing the dyes are sequentially coated and laminated on the conductive substrate. And a step of forming a stacked photoelectric conversion body in which a plurality of photoelectric conversion layers are stacked without sintering.

The present invention can form a photoelectric conversion layer having a laminated structure, and can efficiently photoelectrically convert incident light with a simple structure. Moreover, photoelectric conversion efficiency can be greatly improved by providing different absorption wavelength ranges to the photoelectric conversion layer having a laminated structure. Furthermore, the coating can easily and efficiently form a photoelectric conversion layer having a laminated structure, and it has excellent durability without being sintered, can maintain high photoelectric conversion characteristics over a long period of time, and has high adhesion to the substrate. It is possible to form a laminated photoelectric conversion body having Therefore, it is useful for forming a dye-sensitized solar cell.

FIG. 1 is a graph showing the output characteristics of the dye-sensitized solar cell obtained in the example.

In the present invention, a plurality of coating compositions containing different types of dyes (dyes having different absorption wavelength ranges or absorption peak wavelengths from each other) are used. Each coating composition contains a semiconductor, an ionic binder, and a dye (sensitizing dye), has film-forming properties, and can form a photoelectric conversion layer in close contact with a conductive substrate.

(semiconductor)
As a semiconductor, it can divide roughly into an inorganic semiconductor and an organic semiconductor, and an inorganic semiconductor can be used suitably. Examples of inorganic semiconductors include simple metals, metal compounds (metal oxides, metal sulfides, metal nitrides, and the like). In many cases, the semiconductor is an optical semiconductor that absorbs light and generates an electromotive force.

The constituent elements of the inorganic semiconductor include, for example, Group 2 metals (Ca, Sr, etc.), Group 3 metals (Sc, Y, La, etc.), Group 4 metals (Ti, Zr, Hf, etc.), Group metals (V, Nb, Ta, etc.), Group 6 metals (Cr, Mo, W, etc.), Group 7 metals (Mn, etc.), Group 8 metals (Fe, etc.), Group 9 metals (Co, etc.) , Group 10 metals (Ni, etc.), Group 11 metals (Cu, etc.), Group 12 metals (Zn, Cd, etc.), Group 13 metals (Al, Ga, In, Tl, etc.), Group 14 metals ( Ge, Sn, etc.), Group 15 metals (As, Sb, Bi, etc.), Group 16 elements (Te, etc.), etc. The semiconductor may contain these elements alone or in combination of two or more. For example, the semiconductor may be an alloy, and the metal oxide may be a composite oxide. The semiconductor may contain the above metal and another metal (such as an alkali metal).

Among specific semiconductors, examples of the metal oxide include transition metal oxides [for example, periodic table group 3 metal oxides (yttrium oxide, cerium oxide, etc.), group 4 metal oxides (titanium oxide, oxide). Zirconium, calcium titanate, strontium titanate, barium titanate, etc., Group 5 metal oxides (vanadium oxide, niobium oxide, tantalum oxide (eg, ditantalum pentoxide), etc.), Group 6 metal oxides (chromium oxide) , Tungsten oxide, etc.), Group 7 metal oxides (manganese oxide, etc.), Group 8 metal oxides (iron oxide, ruthenium oxide, etc.), Group 9 metal oxides (cobalt oxide, iridium oxide, cobalt and sodium) Complex oxides), Group 10 metal oxides (such as nickel oxide), Group 11 metal oxides (such as copper oxide), Group 12 metal oxides (such as Zinc oxide, etc.], typical metal oxides [for example, Group 2 metal oxides (eg, strontium oxide), Group 13 metal oxides (eg, gallium oxide, indium oxide, etc.), Group 14 metal oxides (silicon oxide, etc.) , Tin oxide, etc.), Group 15 metal oxides (bismuth oxide, etc.) and the like; Examples of complex oxides containing a plurality of these metals include Group 11 metals and transition metals (other than Group 11 metals) Transition oxides) (for example, complex oxides of copper and Group 3 metals such as CuYO ₂ ), and complex oxides of Group 11 metals and typical metals (for example, CuAlO ₂ , CuGaO ₂ , CuInO _2). A composite oxide of copper and a group 13 metal such as SrCu ₂ O ₂ ; a composite oxide of a copper and group 2 metal such as SrCu ₂ O ₂ ; a composite oxide of silver and a group 13 metal such as AgInO ₂ Is an example That.

The metal oxide is an oxide containing a group 16 element other than these metals and oxygen [for example, a complex oxysulfide of a group 11 metal and a transition metal (transition metal other than the group 11 metal) ( For example, a complex acid selenide of a group 11 metal and a transition metal (a transition metal other than the group 11 metal) (for example, a copper such as LaCuOSe) Etc.) and the like.

The semiconductor includes metal nitride (such as thallium nitride), metal phosphide (such as InP), metal sulfide [for example, CdS, copper sulfide (CuS, Cu ₂ S), composite sulfide (for example, periodic table 11th). Complex sulfides of group metals and typical metals (eg, complex sulfides of copper and group 13 metals of the periodic table such as CuGaS ₂ and CuInS ₂ )), metal selenides (CdSe, ZnSe, etc.), metal halogens Metal compounds (or alloys) such as compounds (CuCl, CuBr, etc.), Periodic Table Group 13 metal-Group 15 metal compounds (GaAs, InSb, etc.), Periodic Table Group 12 metal-Group 16 metal compounds (CdTe, etc.) ); Simple metal (for example, palladium, platinum, silver, gold, silicon, germanium) and the like.

The semiconductor may be a semiconductor doped with other elements. The semiconductor may be an n-type semiconductor or a p-type semiconductor. Typical n-type semiconductors include, for example, a periodic table group 4 metal oxide (such as titanium oxide), a periodic table group 5 metal oxide (such as niobium oxide, tantalum oxide), and a periodic table group 12 metal oxide. (Zinc oxide, etc.), periodic table group 13 metal oxides (gallium oxide, indium oxide, etc.), periodic table group 14 metal oxides (tin oxide, etc.), and the like.

Typical p-type semiconductors include, for example, a periodic table group 6 metal oxide (such as chromium oxide), a periodic table group 7 metal oxide (such as manganese oxide), and a periodic table group 8 metal oxide (iron oxide). Etc.), periodic table group 9 metal oxides (cobalt oxide, iridium oxide, etc.), periodic table group 10 metal oxides (nickel oxide, etc.), periodic table group 11 metal oxides (copper oxide, etc.), periodic table Group 15 metal oxides (such as bismuth oxide), complex oxides of Group 11 metals and transition metals or typical metals (for example, CuYO ₂ , CuAlO ₂ , CuGaO ₂ , CuInO ₂ , SrCu ₂ O ₂ , AgInO) ₂ ), complex oxysulfides of periodic table Group 11 metals and transition metals (for example, LaCuOS, etc.), complex acid selenides of periodic table Group 11 metals and transition metals (for example, LaCuOSe, etc.) And composite sulfides (for example, CuGaS ₂ , CuInS _2, etc.) of Group 11 metals of the periodic table and typical metals.

These semiconductors may be used alone or in combination of two or more. Preferred semiconductors include metal oxides such as titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), copper -Aluminum oxide (CuAlO ₂ ), iridium oxide (IrO), nickel oxide (NiO), doped materials of these metal oxides; strontium titanate, barium titanate, etc .; cadmium sulfide, etc. Of these semiconductors, titanium oxide, zinc oxide, tin oxide and the like are preferable. In particular, an n-type semiconductor, particularly an n-type metal oxide semiconductor such as titanium oxide (TiO ₂ ) is preferable.

The crystal form (crystal form) of titanium oxide may be any of rutile, anatase, and brookite. Preferred titanium oxide is rutile or anatase titanium oxide. When anatase type titanium oxide is used, it is easy to form a photoelectric conversion layer with high adhesion over a long period of time with respect to the substrate. On the other hand, rutile type titanium oxide is preferable from the viewpoint of conductivity and durability. As described above, the titanium oxide may be titanium oxide doped with other elements.

The shape of the semiconductor (for example, a metal oxide such as titanium oxide) is not particularly limited, and may be in the form of particles, fibers (or needles or rods), plates, and the like. A preferable semiconductor form may be particulate, needle-like, or fibrous, and a particulate semiconductor (semiconductor particle) may be used.

The average particle diameter (average primary particle diameter) of the semiconductor particles (particulate or acicular semiconductor) can be selected from the range of about 1 to 1000 nm (for example, 1 to 700 nm), and is usually nano-sized (nanometer size), for example, It may be about 1 to 500 nm (for example, 2 to 400 nm), preferably 3 to 300 nm (for example, 4 to 200 nm), more preferably about 5 to 100 nm (for example, 6 to 70 nm), and 50 nm or less, for example, 1 May be about 50 nm (for example, 2 to 40 nm), preferably about 3 to 30 nm (for example, 4 to 25 nm), more preferably about 5 to 20 nm (for example, 6 to 15 nm), and usually about 10 to 50 nm. There may be. Such nanometer-sized semiconductor particles have high transparency to visible light, and can efficiently photoelectrically convert incident light including at least the visible light wavelength region.

The average fiber diameter of the acicular (or fibrous) semiconductor may be, for example, about 1 to 300 nm, preferably 10 to 200 nm, and more preferably about 50 to 100 nm. The average fiber length of the acicular (or fibrous) semiconductor may be about 10 to 2000 nm, preferably 50 to 1000 nm, and more preferably about 100 to 500 nm. The aspect ratio of the acicular semiconductor may be, for example, about 2 to 200, preferably about 5 to 100, and more preferably about 20 to 40. Note that the needle-like or fibrous semiconductor may form nanofibers (eg, titanium oxide nanofibers (TNF)) or nanotubes (eg, titanium oxide nanotubes (TNT)).

The specific surface area of the semiconductor (for example, a particulate or fibrous semiconductor) may be, for example, about 1 to 600 m ² / g, preferably 2 to 500 m ² / g, more preferably about 3 to 400 m ² / g. . In particular, the specific surface area of the semiconductor particles is, for example, 5 to 600 m ² / g (eg 10 to 550 m ² / g), preferably 20 to 500 m ² / g (eg 30 to 450 m ² / g), more preferably It may be about 40 to 400 m ² / g (for example, 50 to 350 m ² / g), 50 m ² / g or more [for example, 50 to 500 m ² / g, preferably 75 to 450 m ² / g, more preferably 100 to 400 m ² / g, particularly 150 to 350 m ² / g (for example, 200 to 350 m ² / g)]. Note that the specific surface area of the fibrous or needle-like semiconductor is about 1 to 100 m ² / g, preferably 2 to 70 m ² / g, more preferably 3 to 50 m ² / g (for example, 4 to 30 m ² / g). It may be.

The semiconductor may be a commercially available product or may be synthesized using a conventional method. For example, a dispersion of titanium oxide can be obtained by the method described in Japanese Patent No. 452886.

In the plurality of coating compositions, the type of semiconductor may be the same or different.

(Ionic binder or ionic polymer)
In the present invention, by combining a semiconductor and an ionic polymer (hereinafter sometimes referred to as an ionic binder), a photoelectric conversion layer having excellent photoelectric conversion characteristics can be formed without sintering. The reason for this is not clear, but it is because the ionic polymer is immobilized by bonding (chemical bonding, hydrogen bonding, etc.) to the semiconductor [especially nano-sized semiconductor particles (semiconductor nanoparticles)]. It may not only improve the properties, but also function as an electrolyte (solid electrolyte) that electronically couples with the excited state of the semiconductor and transports charges from the semiconductor. Moreover, an ionic polymer acts as a binder, can maintain a photoelectric conversion characteristic over a long period of time, and can improve the adhesiveness of the photoelectric conversion layer (or semiconductor) with respect to a board | substrate.

In addition, for the formation of the photoelectric conversion layer, an ionic polymer may be selected depending on the type of semiconductor. For example, in (i) an n-type semiconductor, an ionic polymer including an anionic polymer is selected, ii) For a p-type semiconductor, an ionic polymer including a cationic polymer may be selected.

The ionic polymer (ionic polymer) may be any polymer having an electrolyte property (that is, a polymer electrolyte) and has an anionic polymer, a cationic polymer, and an amphoteric polymer (both an anionic group and a cationic group). Any of an anionic polymer and a cationic polymer (especially an anionic polymer) may be used. In particular, the ionic polymer may be an ion exchange resin (or an ion exchanger or a solid polymer electrolyte). The ionic polymers may be used alone or in combination of two or more.

An anionic polymer usually has an acid group (or acidic group), for example, a carboxyl group, a sulfo group (or sulfonic acid group), etc., and has a single acid group (or acidic group). It may also have a plurality of different acid groups (or acidic groups). In addition, the acid group may be partially or entirely neutralized.

Typical anionic polymers include cation exchange resins (cationic ion exchange resins, acid type ion exchange resins), such as weakly acidic cation exchange resins having carboxyl groups, strong acids having sulfonic acid groups (sulfo groups). Examples of weakly acidic cation exchange resins include (meth) acrylic acid resins (for example, poly (meth) acrylic acid; (meth) acrylic acid-styrene copolymers ( And a fluorine-containing resin having a carboxyl group (perfluorocarboxylic acid resin).

Preferred anionic polymers include strongly acidic cation exchange resins. Examples of the strongly acidic ion exchange resin include a styrene resin having a sulfo group (for example, polystyrene sulfonic acid, a sulfonated product of a styrene polymer); a fluorine-containing resin having a sulfo group (or a fluoro resin), for example, hydrophobic Fluorosulfonic acid resin having a functional poly (fluoro C _2-3 alkylene) main chain and a fluoro C _2-8 alkyl side chain having a sulfo group or a fluoro C _2-8 alkyl ether side chain having a sulfo group It is done. As this fluorosulfonic acid resin, a copolymer of fluoroalkene (perfluoro C _2-3 alkene such as tetrafluoroethylene) and sulfofluoroalkyl-fluorovinyl ether (sulfoperfluoroalkyl-perfluorovinyl ether, etc.), For example, a copolymer of tetrafluoroethylene and [2- (2-sulfotetrafluoroethoxy) hexafluoropropoxy] trifluoroethylene or [2- (2-sulfotetrafluoroethyl) hexafluoropropoxy] trifluoroethylene ] And the like (particularly perfluorosulfonic acid resin). The fluorine-containing resin having a sulfo group is available from DuPont under the trade name “Nafion” series or the like, and may be obtained in the form of an aqueous solution or an aqueous dispersion.

The cationic polymer is usually a primary group such as a basic group (alkaline group), for example, an amino group [for example, an amino group, a substituted amino group (for example, a mono- or dialkylamino group such as a dimethylamino group) or the like. Primary or tertiary amino group], imino group (—NH—, —N <), quaternary ammonium base (for example, trialkylammonium base such as trimethylammonium base), etc., and a single base May have a functional group, and may have a plurality of different basic groups. In addition, the basic group may be partially or completely neutralized.

Typical cationic polymers include anion exchange resins (anion-type ion exchange resins, base-type ion exchange resins), such as allylamine monomers (eg, allylamine, diallylamine, diallylalkylamine (diallylmethylamine, diallyl). Ethylamine, etc.)) or a copolymer or a copolymer of an allylamine monomer and a copolymerizable monomer [for example, polyallylamine, allylamine-dimethylallylamine copolymer, diallylamine-sulfur dioxide copolymer Etc.]; Vinylamine monomer homopolymer or copolymer (for example, polyvinylamine etc.); (meth) acrylic monomer homopolymer or copolymer having amino group [aminoalkyl (meth) acrylate (for example, N, N-dimethylaminoethyl (meth) acrylate, N N, such as N- dimethylaminopropyl (meth) acrylate, N- dialkylamino _{C 1-4} alkyl (meth) acrylate), aminoalkyl (meth) acrylamides (e.g., N, N- dimethylaminoethyl (meth) acrylamide N, N-dialkylamino C _1-4 alkyl (meth) acrylamide) or the like]; heterocyclic amine polymer [eg, imidazole polymer (eg, polyvinylimidazole, etc.), pyridine polymer ( For example, polyvinyl pyridine, etc.), pyrrolidone polymers (eg, polyvinyl pyrrolidone)], amine-modified resins [amine-modified epoxy resins, amine-modified silicone resins, etc.], imine monomers alone or copolymers [eg, poly Alkyleneimine (for example, For example, polyethyleneimine, etc.)], and quaternary ammonium base-containing polymers.

As the quaternary ammonium base-containing polymer, for example, a polymer obtained by quaternizing an amino group or imino group of the above-described amine-based polymer or imine-based polymer, for example, N, N, N-trialkyl-N -(Meth) acryloyloxyalkylammonium salts [for example, tri-C ₁ such as trimethyl-2- (meth) acryloyloxyethylammonium chloride, N, N-dimethyl-N-ethyl-2- (meth) acryloyloxyethylammonium chloride, etc. _-10 alkyl (meth) acryloyloxy C _2-4 alkylammonium salt] or a copolymer thereof; vinylaralkylammonium salt-based polymer, for example, N, N, N-trialkyl-N- (vinylaralkyl) ammonium salt ( For example, trimethyl-p-vinyl Emissions Jill chloride, N, N-dimethyl -N- ethyl -p- vinylbenzyl ammonium chloride, N, N-diethyl -N- tri _{C 1} such as methyl -N-2- (4- vinylphenyl) ethyl ammonium chloride _-10 alkyl (vinyl-C _6-10 aryl C _1-4 alkyl) ammonium salt), N, N-dialkyl-N-aralkyl-N- (vinylaralkyl) ammonium salt (eg, N, N-dimethyl-N— N, N-diC _1-10 alkyl- _{NC 6-10} aryl C _1-4 alkyl-N- (vinyl-C _6-10 aryl C _1-4 alkyl) such as benzyl-p-vinylbenzylammonium chloride Ammonium salt)] homopolymer or copolymer, etc .; cationized cellulose [eg, hydroxy group-containing cellulose Derivatives (e.g., hydroxy _{C 2-4} alkyl cellulose such as hydroxyethyl cellulose) and the quaternary ammonium salt (e.g., trialkyl ammonium bases etc.) epoxy compound having a (e.g., N, N, N-trialkyl -N- glycidyl Reaction products with ammonium salts), polymers obtained by introducing quaternary ammonium bases into styrene resins, and the like.

Cationic cellulose (cationized cellulose) is from Daicel Co., Ltd. under the trade name “Gerner”, polyallylamine is from Nito-Bo Medical Co., Ltd. under the trade name “PAA”, and amine-modified silicone resins are from Shin-Etsu Chemical Co., Ltd. It can be obtained from Co., Ltd. as the product name “KF” series.

In the quaternary ammonium base-containing polymer, examples of the salt include halide salts (for example, chloride, bromide, iodide, etc.), carboxylates (for example, alkane salts such as acetate), sulfonates, etc. Is mentioned.

A preferable cationic polymer includes a strongly basic cationic polymer (anion exchange resin) such as a quaternary ammonium base-containing polymer.

The ionic polymer may be composed of only an anionic or cationic polymer, or may be combined with another ionic polymer (for example, an amphoteric polymer). The ratio of the anionic or cationic polymer to the whole ionic polymer is, for example, 30% by weight or more (for example, 40 to 99% by weight), preferably 50% by weight or more (for example, 60 to 98% by weight), and more preferably It may be 70% by weight or more (for example, 80 to 97% by weight).

The pH of the aqueous solution or dispersion of the ionic polymer may be acidic, neutral or alkaline, and the pH may be selected according to the ionic polymer. For example, the pH (25 ° C.) of the ionic polymer may be selected from the range of 10 or less (eg, 0.1 to 8), for example, 0.2 to 7 (eg, 0.3 to 5), Preferably, it may be 0.5 to 4 (for example, 0.7 to 3), more preferably about 1 to 3.

In addition, when an ionic polymer having a relatively high pH is used, aggregation of semiconductors (for example, titanium oxide nanoparticles) may be suppressed, so that the photoelectric conversion characteristics may be further improved. Moreover, the adhesiveness with respect to a board | substrate may be improved efficiently. The pH (25 ° C.) of such an ionic polymer is, for example, 3 or more (for example, 4 to 14), preferably 5 or more (for example, 6 to 13), and more preferably 7 or more (for example, 7 to 12). It may be a degree.

In particular, the pH (25 ° C.) of an anionic polymer (eg, a strongly acidic ion exchange resin) or an ionic polymer containing an anionic polymer is, for example, 4 to 14 (eg, 5 to 13), preferably 5.5 to It may be about 12 (for example, 7 to 12), more preferably about 6 to 11 (for example, 7 to 9).

The pH (25 ° C.) of the cationic polymer (eg, strongly basic anion exchange resin) or the ionic polymer including the cationic polymer can be selected from the range of 5 or more (eg, 6 to 14), for example, 7 to It may be 14 (for example, 8 to 13), preferably 9 to 13 (for example, 9.5 to 13), and more preferably about 10 to 13.

PH can be adjusted by a conventional method (for example, a method of neutralizing with a base or a method of neutralizing with an acid). In the neutralized acid group, the counter ion may be, for example, an alkali metal (for example, lithium, sodium, potassium, etc.), a tertiary amine, or the like.

The ionic polymer (anionic polymer or the like) may have a crosslinked structure, but an ionic polymer that does not have a crosslinked structure (or has a very low degree of crosslinking) is preferable.

In the ionic polymer (ion exchange resin), the ion exchange capacity is 0.1 to 5.0 meq / g (for example, 0.15 to 4.0 meq / g), preferably 0.2 to 3.0 meq / g ( For example, it may be about 0.3 to 2.0 meq / g), more preferably about 0.4 to 1.5 meq / g (for example, 0.5 to 1.0 meq / g).

The molecular weight of the ionic polymer is not particularly limited as long as it is in a range that can be dissolved or dispersed in a solvent. In addition, a fluorine-containing resin having a sulfo group (fluororesin) or the like is dispersed in a nanometer size, and the molecular weight may not be measured accurately.

In general, it seems that the photoelectric conversion efficiency decreases as the proportion of the binder increases, but by using an ionic polymer, not only can a photoelectric conversion layer with high photoelectric conversion characteristics be formed, but also photoelectric conversion with respect to a conductive substrate. It can improve by the adhesiveness of a layer and the adhesiveness of an adjacent photoelectric converting layer. Therefore, in this invention, even if the quantitative ratio of the ionic polymer with respect to a semiconductor is large, a photoelectric conversion characteristic and the adhesiveness with respect to a board | substrate can be improved. The ratio of the ionic polymer can be selected from the range of about 1 to 100 parts by weight with respect to 100 parts by weight of the semiconductor, for example, 3 to 75 parts by weight (for example, 4 to 60 parts by weight), preferably 5 to 50 parts by weight. Parts (eg 6 to 40 parts by weight), more preferably 7 to 30 parts by weight (eg 10 to 25 parts by weight), usually 5 to 20 parts by weight (eg 10 to 15 parts by weight). Good. In addition, when there is too little quantity of an ionic polymer, there exists a possibility that adhesiveness may fall, and when too large, there exists a possibility that a photoelectric conversion characteristic may fall.

In the plurality of coating compositions, the type of ionic polymer may be the same or different.

(Dye)
Dyes that function as sensitizers (sensitizing dyes, photosensitizing dyes) include, for example, organic dyes, inorganic dyes (for example, carbon pigments, chromate pigments, cadmium pigments, ferrocyanide pigments, metals) Oxide pigments, silicate pigments, phosphate pigments, etc.). The dyes may be used alone or in combination of two or more.

As the organic dye (organic dye or organic pigment), conventional or known dyes can be used. For example, ruthenium complex dyes, osmium complex dyes, porphyrin dyes (magnesium porphyrin, zinc porphyrin, etc.), chlorophyll dyes (chlorophyll, etc.) Xanthene dyes (rhodamine B, sulforhodamine B, erythrosine, etc.), cyanine (or polymethine) dyes (merocyanine, quinocyanine, cryptocyanine, etc.), phthalocyanine dyes (this dye is referred to as “TT1” dye) A plurality of alkyl groups (such as three t-butyl groups) and a carboxyl group for enhancing solubility in organic solvents), azo dyes, perylene dyes, perinone dyes, Coumarin dye, quinone dye, quinone imine color , Diphenylmethane dyes, triphenylmethane dyes, indigo dyes, pyrazolone dyes, stilbene dyes, thiazole dyes, quinoline dyes, acridine dyes, anthraquinone dyes, squarylium dyes, azomethine dyes, quinophthalone dyes Quinacridone dyes, indoline dyes (such as dyes referred to as “D149” dyes), isoindoline dyes, nitroso dyes, pyrrolopyrrole dyes, xanthene dyes, carbazole dyes (for example, “MK-2”) A dye called a dye (2-cyano-3- [5 ′ ″-(9-ethyl-9H-carbazol-3-yl] -3 ′, 3 ″, 3 ′ ″, 4-tetra-n- Hexyl- [2,2 ′, 5 ′, 2 ″, 5 ″, 25 ′ ″]-quaterlthiophen-5-yl] acrylic acid), etc. ), Basic dyes (methylene blue, basic blue 12, etc.) and the like.

Further, the dye may be a thiophene or acrylic acid dye (3- {5 ′-[N, N-bis (9,9-dimethylfluoren-2-yl) phenyl] -2,2′-bisthiophene-5 Yl} -2-cyanoacrylic acid (sometimes referred to as “JK2” dye), 2-cyano-3- (5- (4-ethoxyphenyl) thiophen-2-yl) acrylic acid (“P5” dye) And thiazole dyes (3-carboxymethyl-5- (3- (4-sulfobutyl) -2 (3H) -benzothiazolidene) -2-thioxo-4-thiazolidinone sodium Salts (such as “NK3705” dyes), metal-free panchromatic dyes (for example, dyes into which phenoxazine as an electron donor and rhodamine as an electron acceptor are introduced). It may be.

Examples of the ruthenium complex dye include ruthenium pyridine complexes, such as ruthenium bipyridine complexes [for example, cis-bis (isothiocyanato) bis (2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium (II)]. Bistetrabutylammonium (also known as “N719” dye, “Red dye”), cis-bis (isothiocyanato) bis (2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium (II) (also known as “N3”) Dye), cis-bis (isothiocyanato) (2,2′-bipyridyl-4,4′-dicarboxylato) (2,2′-bipyridyl-4,4′-dinonyl) ruthenium (II) (also known as Z) -907 dye), cis-bis (isothiocyanato) bis (2,2′-bipyridyl-4,4′-dicarboxylato) ruteniu (II), cis-bis (cyanide) (2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium (II), tris (2,2′-bipyridyl-4,4′-dicarboxylato) Ruthenium (II) dichloride, cis-bis (thiocyanato) bis (2,2′-biquinolyl-4,4′-dicarboxylato) ruthenium (II) and the like]; ruthenium terpyridine complexes [eg tris (isothiocyanato) ruthenium ( II) -2,2 ′: 6 ′, 2 ″ -terpyridine-4,4 ′, 4 ″ -tricarboxylic acid tristetrabutylammonium salt (also known as “N749” dye, “black dye”), etc.] It can be illustrated. In such a pyridine complex, a pyridinecarboxylic acid unit (at least one selected from pyridinecarboxylic acid, bipyridyldicarboxylic acid, and terpyridyltricarboxylic acid) and isothiocyanate coordinate to ruthenium, resulting in high photoelectric conversion efficiency. There are many. Ruthenium complex dyes include complexes with phenanthroline.

As the dye (including ruthenium pyridine complex), a commercially available product may be used, and known documents such as J. Am. Chem. Soc. 115 (1993) 6382, J. Am. Chem. Soc. 123 (2001). ) 1613, Inorganica Chimica Acta.322 (2001) 7, etc.

These pigments may be used alone or in combination of two or more. The absorption wavelength range may be expanded by combining a plurality of dyes, but when a plurality of dyes are mixed and supported or fixed on a semiconductor, they are deactivated due to energy transition between the dyes and the photoelectric conversion efficiency decreases. There is.

The plurality of coating compositions (or coating agents) only need to contain pigments having different absorption wavelength ranges or absorption peak wavelengths, respectively, and by incorporating a plurality of pigments into a plurality of photoelectric conversion layers in a laminated form. The photoelectric conversion efficiency can be greatly improved. For example, it is preferable that the plurality of dyes contained in the photoelectric conversion layer in the laminated form can be absorbed over the entire wavelength region of the emission spectrum of sunlight, and as a whole, at least the visible region or the visible light region (for example, the wavelength region 400 to 400). 700 nm light), preferably in the visible region including the wavelength region of the ultraviolet region (eg 200 to 400 nm) and / or the infrared region (eg 700 to 1800 nm), in particular about 200 to 1500 nm (eg 300 to 1300 nm). It is preferable that it is possible to absorb the wavelength region. In addition, as the different wavelength regions are described depending on the books, the wavelengths in the visible region, the ultraviolet region, and the infrared region are not strict numerical values, and the wavelengths in the respective regions are described as approximate indicators. is there. Therefore, the visible light region can be, for example, a wavelength region of 300 to 800 nm (for example, 380 to 730 nm, particularly 400 to 700 nm).

The plurality of dyes include, for example, a dye having an absorption wavelength region or an absorption peak wavelength in the ultraviolet region, a dye having an absorption wavelength region or an absorption peak wavelength in the visible light region, and an absorption wavelength region or an absorption peak wavelength in the infrared region. Can also be classified into dyes having an absorption wavelength region or absorption peak wavelength in the ultraviolet region and visible light region, and dyes having an absorption wavelength region or absorption peak wavelength in the infrared region. A dye having an absorption wavelength range or absorption peak wavelength in the ultraviolet range and visible light range, and a dye having an absorption wavelength range or absorption peak wavelength in the visible light range and infrared range can also be classified. As for the absorption wavelength range of a typical dye, for example, “JK2” dye shows broad absorption in a wavelength range of about 450 to 550 nm, “P5” dye shows an absorption range of about 390 to 430 nm, and “N719” “The dye has an absorption peak at 540 nm and absorption in a wavelength range of about 380 to 410 nm and a wavelength range of about 530 to 550 nm, and“ N749 ”dye has an absorption peak at around 600 nm and about 370 to 420 nm. The “MK-2” dye has an absorption peak at 480 nm and a broad absorption range at a wavelength range of about 450 to 650 nm, “TT1”. Phthalocyanine dyes such as dyes show a sharp absorption range at about 680 to 710 nm. Therefore, in the present invention, a stacked photoelectric conversion layer is formed by combining a plurality of dyes having different absorption wavelength ranges.

The absorption wavelength region or absorption peak wavelength (especially absorption peak wavelength) of the plurality of dyes is 10 nm or more (for example, about 10 to 200 nm), preferably 20 nm or more (for example, about 20 to 200 nm), more preferably. It is preferably shifted by 30 nm or more (for example, about 30 to 150 nm), usually 10 to 150 nm (for example, 25 to 120 nm), preferably 20 to 100 nm (for example, 30 to 100 nm or 30 to 80 nm). There are many cases.

More specifically, a first coating composition containing a dye “P5” dye, a second coating composition containing an “N719” dye, a third coating composition containing an “N749” dye are prepared, By sequentially applying the coating composition to the conductive substrate, a stacked photoelectric conversion layer may be formed. The first coating composition containing the “N719” dye, the second coating containing the “N749” dye. A multilayer photoelectric conversion layer may be formed by preparing a coating composition and sequentially applying each coating composition to a conductive substrate. In addition, as long as it is a combination which does not impair or improve conversion efficiency, each coating composition may contain not only a single pigment but a plurality of pigments.

In addition, a pigment | dye is normally contained in a photoelectric converting layer with the form carry | supported or adhere | attached (or fixed) on the semiconductor (or porous semiconductor surface). The dye may be attached (or immobilized) to the semiconductor by adsorption (physical adsorption), chemical bonding, or the like. Therefore, a dye that easily adheres to or bonds to a semiconductor, for example, a dye having a functional group such as a carboxyl group, an ester group, a sulfo group, or a cyano group (for example, a carboxyl group such as an “N719” dye or an “N749” dye) A ruthenium dye, a phthalocyanine dye having a carboxyl group, such as a “TT1” dye, a carbazole dye or a thiophene dye having a carboxyl group and a cyano group, such as a “JK2” dye, a “P5” dye, and an “MK-2” dye, An acrylic acid dye or a thiazole dye having a sulfo group such as “NK3705” dye) may be selected. Such a dye is not only difficult to bind to and desorb from a semiconductor surface such as titanium oxide, but is also considered to be useful in increasing the photoelectric conversion efficiency by electronically coupling with the excited state of the semiconductor.

The ratio (adhesion or adsorption ratio) of the dye may be selected so as to be in the range of the following formula in association with the semiconductor and the ionic binder or ionic polymer, for example.

_{_{0 <(I A × I S}} + D A × D S) / S S ≦ 1
(Wherein, I _A is the number of ionic groups of the ionic binder or ionic polymers, I _S is the number of occupied area per ionic group, D _A dye (dye molecules), D _S dye (Occupied area per piece, S _S indicates the surface area of the semiconductor.)
In the above formula, I _A is the total number of ionic groups, for example, the weight (g) and Avogadro number of ionic binder or ionic polymer to the ion exchange capacity of the ion binder or ionic polymer (meq / g) It can be calculated by multiplication, and usually I _A × I _S <S _S. I _S, D _S, respectively, an ionic group one occupied area (m ^2), a occupation area of the dye molecule (m ^2), as the occupied area, the use of the maximum projected area in the projection of the molecule Can do.

The coating composition only needs to contain an amount of the dye that can be adsorbed or immobilized on the semiconductor, and the amount of the dye is, for example, 0.1 to 20 parts by weight (for example, 100 parts by weight of the semiconductor) 0.5 to 15 parts by weight), preferably 1 to 10 parts by weight (for example, 1.5 to 8 parts by weight), more preferably about 2 to 6 parts by weight (for example, 3 to 5 parts by weight). Also good.

The coating composition may contain a solvent. The solvent may be water and / or an organic solvent. Examples of the organic solvent include alcohols (alkanols such as methanol, ethanol, isopropanol and butanol) and hydrocarbons (aromatic carbonization such as toluene and xylene). Hydrogen, aliphatic hydrocarbons such as hexane, alicyclic hydrocarbons such as cyclohexane), halogenated hydrocarbons (for example, haloalkanes such as dichloromethane and chloroform), esters (ethyl acetate, butyl acetate, etc.) , Ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.), ethers (cyclic ethers such as dioxane, tetrahydrofuran, chain ethers such as diisopropyl ether, propylene glycol monomethyl ether, diethylene glycol dimethyl ether), celloso (Ethylene glycol monoalkyl ethers such as methyl cellosolve, ethyl cellosolve, butyl cellosolve), carbitols (diethylene glycol monoalkyl ethers such as methyl carbitol, ethyl carbitol, butyl carbitol), cellosolve acetates (such as methyl cellosolve acetate) Cellosolve acetate, and propylene glycol monomethyl ether monoacetate similar to cellosolve acetate), carbitol acetates, nitriles (eg acetonitrile, benzonitrile, etc.), nitro solvents (eg nitrobenzene, etc.), and the like. The solvents may be used alone or in combination of two or more.

In the composition containing the solvent, the ratio of the solid content (or non-volatile component) is, for example, 0.1 to 60% by weight (eg 1 to 50% by weight), preferably 5 to 40%, depending on the coating method and the like. It may be about wt% (for example, 10 to 30 wt%). In the present invention, the dispersion stability of the semiconductor can be improved even when the solid content including the semiconductor is high.

The coating composition may be prepared by a conventional method, for example, mixing a semiconductor (such as titanium oxide), an ionic polymer, and a dye, or a non-adsorbed or immobilized dye on a semiconductor (such as) in advance. You may prepare by mixing a sintered semiconductor (non-sintered titanium oxide etc.) and an ionic polymer. Usually, it is often prepared by mixing and dispersing a solution or dispersion of an ionic polymer (such as an aqueous dispersion), a semiconductor (such as titanium oxide), and a dye. Moreover, you may prepare a several coating composition for every pigment | dye from which an absorption wavelength range or an absorption peak wavelength differs. The pH of the coating composition containing the solvent is not particularly limited and can be selected from the same range as the pH of the ionic polymer. The pH can be adjusted at an appropriate stage, for example, a solution of the ionic polymer or The pH of the dispersion may be adjusted and mixed with the semiconductor and the dye.

The coating composition of the present invention is useful for laminating a plurality of photoelectric conversion layers by coating to form a laminated photoelectric conversion layer or a laminated photoelectric converter (laminated body) having different dye regions in the thickness direction.

[Laminated Photoelectric Converter and Method for Producing the Same]
The laminated photoelectric conversion body of the present invention includes a photoelectric conversion layer in which a plurality of photoelectric conversion layers are stacked, and can usually be formed on a conductive substrate. The conductive substrate may be composed of only a conductor, but may usually include a base substrate and a conductive layer (or conductive film) formed on the substrate.

As the base substrate, an inorganic substrate (for example, a glass substrate, a ceramic substrate, etc.), a plastic substrate or a plastic film [for example, a polyester resin (for example, polyethylene terephthalate, polyethylene naphthalate), a polycarbonate resin, a cycloolefin resin, polypropylene -Based resins, cellulose-based resins (such as cellulose triacetate), polyether-based resins (such as polyethersulfone), polysulfide-based resins (such as polyphenylene sulfide), and substrates or films formed of plastics such as polyimide resins] It is done. In the present invention, since a semiconductor sintering step is unnecessary, a plastic substrate (plastic film) can be used as the base substrate. The base substrate is usually a transparent substrate.

The conductive layer may be, for example, a conductive metal oxide [eg, tin oxide, indium oxide, zinc oxide, antimony-doped metal oxide (such as antimony-doped tin oxide), tin-doped metal oxide (such as tin-doped indium oxide), aluminum Doped metal oxide (such as aluminum-doped zinc oxide), gallium-doped metal oxide (such as gallium-doped zinc oxide), fluorine-doped metal oxide (such as fluorine-doped tin oxide), and the like. These conductive layers may be formed by combining the above components alone or in combination of two or more. The conductive layer may usually be a transparent conductive layer.

A laminated photoelectric conversion body can be formed on a conductive substrate by sequentially coating and laminating a plurality of coating compositions (or inks) on the conductive substrate (or its conductive layer). The plurality of coating compositions (or inks) each contain a plurality of pigments having different absorption wavelength ranges or absorption peak wavelengths. In this method, each photoelectric conversion layer can be formed without sintering. Therefore, in the laminated photoelectric conversion body, a plurality of dyes can be contained in each photoelectric conversion layer in a layered form.

The number of stacked photoelectric conversion layers with a plurality of coating compositions is not particularly limited, and may be, for example, about 2 to 10 layers (for example, 2 to 7 layers), and usually 2 to 5 layers (for example, 2 layers). ~ 4 layers), in particular 2 or 3 layers. For example, a plurality of dyes having different absorption peak wavelengths or absorption wavelength ranges may be used, and a plurality of photoelectric conversion layers that absorb different wavelength ranges may be stacked. For example, a first photoelectric conversion layer including a first dye and a semiconductor and a second photoelectric conversion layer including a second dye and a semiconductor may be stacked on the conductive substrate, and the second photoelectric conversion layer may be stacked. A third photoelectric conversion layer containing a third dye and a semiconductor may be stacked on the photoelectric conversion layer. In the plurality of photoelectric conversion layers, the absorption wavelength region or the absorption peak wavelength (particularly the absorption peak wavelength) of the plurality of dyes is the same as described above, and each photoelectric conversion layer is, for example, 10 nm or more (for example, 10 to About 200 nm), particularly about 20 to 100 nm (for example, 30 to 80 nm), or about 10 to 150 nm.

The order of coating of the plurality of coating compositions (or inks) is not particularly limited, and in a laminate in which a plurality of photoelectric conversion layers having different absorption wavelengths (for example, adjacent photoelectric conversion layers) are stacked, different absorption wavelength ranges or A dye having an absorption peak wavelength (particularly, a dye having an absorption peak wavelength) may be contained in an arbitrary photoelectric conversion layer, the absorption peak wavelength or absorption wavelength region of a plurality of dyes, and the stacking order of the photoelectric conversion layers (lamination Position). For example, a photoelectric conversion layer that absorbs a short wavelength (for example, at least a wavelength in the visible light region, or a wavelength in the ultraviolet region to a visible light region) is changed to a long wavelength (for example, a wavelength in the near infrared region, or a visible light region or near It may be positioned on the incident side (light receiving side) of the photoelectric conversion layer that absorbs (wavelength in the infrared region), or may be positioned in the middle between the incident side and the transmission side. More specifically, the first coating composition containing the first dye whose absorption peak wavelength or absorption wavelength region is in the short wavelength region, and the second dye whose absorption peak wavelength or absorption wavelength region is in the long wavelength region When the third coating composition containing a second coating composition containing a third dye containing a third dye having an absorption peak wavelength or an absorption wavelength range in the intermediate wavelength range is used, the incident side (conductive substrate or light receiving side) A plurality of photoelectric conversion layers from the photoelectric conversion layer to the transmission side photoelectric conversion layer are divided into the order of the second coating composition / third coating composition / first coating composition, third coating composition / Coated in the order of second coating composition / first coating composition, second coating composition / first coating composition / third coating composition, etc. It may be.

In a preferred embodiment, the photoelectric conversion layer that absorbs a short wavelength (for example, a wavelength in the visible light region or a wavelength in the ultraviolet region to the visible light region) has a long wavelength (for example, a wavelength in the near infrared region or a visible light region). The dye contained in the photoelectric conversion layer on the incident side (conductive substrate or light reception side) is located closer to the light receiving side than the photoelectric conversion layer absorbing the wavelength in the near infrared region), and the dye contained in the photoelectric conversion layer on the transmission side. It has an absorption peak wavelength in a shorter wavelength region than the absorption peak wavelength. That is, in the plurality of stacked photoelectric conversion layers, the absorption wavelength range or the absorption peak wavelength shifts from a short wavelength to a long wavelength continuously or step by step from the light receiving side photoelectric conversion layer to the transmission side photoelectric conversion layer. The plurality of dyes are sequentially contained. In other words, a dye-sensitized photoelectric conversion layer containing a dye capable of absorbing a short wavelength region (for example, a short wavelength region in the visible light region) is formed on the light receiving side, and a long wavelength region (for example, a visible light region in the transmission side). A dye-sensitized photoelectric conversion layer containing a dye capable of absorbing (long wavelength region) is formed. Among the plurality of photoelectric conversion layers, the photoelectric conversion layer on the light receiving side has an absorption peak wavelength in a short wavelength region of the visible light region (for example, about 300 to 600 nm, preferably about 350 to 580 nm, more preferably about 370 to 570 nm). 1 pigment may be contained. In addition, the photoelectric conversion layer on the side opposite to the light receiving side (transmission side) has an absorption peak wavelength in the long wavelength region of the visible light region (for example, about 550 to 800 nm, preferably about 570 to 750 nm, more preferably about 580 to 700 nm). You may contain the 2nd pigment | dye which has. Furthermore, the absorption peak wavelengths of the plurality of dyes (in particular, the absorption peak wavelengths of the first dye and the second dye, or the absorption peak wavelengths of the dyes contained in the adjacent photoelectric conversion layer) are photoelectric conversions on the light receiving side. The layer and the photoelectric conversion layer opposite to the light receiving side (transmission side) may be separated by 10 nm or more, for example, 10 to 200 nm (for example, 20 to 200 nm), preferably 30 to 200 nm (for example, 30 to 30 nm). 170 nm), more preferably about 50 to 150 nm, or about 30 to 150 nm (for example, 50 to 130 nm). For example, the absorption peak wavelength of the first dye is shorter than the absorption peak wavelength of the second dye, for example, 10 nm or more (eg, 10 to 200 nm, preferably 20 to 200 nm, like the difference in the peak wavelength) Further preferably, the wavelength may be as short as about 50 to 150 nm.

For example, a plurality of photoelectric conversion layers (laminates) in a stacked form are formed on the conductive substrate based on the relationship between the absorption peak wavelength or absorption wavelength range of the plurality of dyes and the stacking order of the photoelectric conversion layers. These coating compositions can be sequentially coated. In the case where the first to third coating compositions are used, the stacked photoelectric conversion layer may be formed of, for example, a conductive substrate, a first coating composition / third coating composition / second coating composition. It may be formed by coating in order, or by coating in the order of first coating composition / second coating composition / third coating composition.

The coating method is not particularly limited. For example, air knife coating method, roll coating method, gravure coating method, blade coating method, doctor blade method, squeegee method, dip coating method, spray method, spin coating method, ink jet printing method, etc. It may be. Further, after coating, the coating film may be dried at a predetermined temperature (eg, room temperature to about 150 ° C., preferably about 50 to 120 ° C.). In addition, in application | coating of several coating composition, in order to suppress that a pigment | dye mixes in the interface of an adjacent photoelectric converting layer, the process of apply | coating a coating composition and the process of drying a coating film are repeated, and photoelectric conversion is carried out. Layers may be stacked. By applying a coating composition to the dried photoelectric conversion layer formed in such a drying step and drying it, it is possible to prevent mixing of the dye in the boundary region between adjacent photoelectric conversion layers, and to increase the thickness of multiple dyes. It can be clearly formed in layers sequentially in the direction.

In the present invention, a photoelectric conversion layer having high photoelectric conversion characteristics (further, durability and adhesion to a substrate) is obtained without sintering (or baking) the semiconductor by heating at a high temperature (for example, 500 ° C. or higher). Can be formed.

The total thickness of the stacked photoelectric conversion layers is, for example, about 0.1 to 100 μm (for example, 0.5 to 70 μm), preferably 1 to 50 μm (for example, 3 to 30 μm), and more preferably about 5 to 20 μm. May be. The thickness of each photoelectric conversion layer can be selected from a range of about 0.01 to 50 μm (for example, 0.5 to 30 μm, particularly 1 to 15 μm) depending on the number of layers, the extinction coefficient of the dye, and the like. In addition, each photoelectric conversion layer and the total thickness can be freely adjusted by the number of coatings (number of laminations).

In order to photoelectrically convert incident light, the ratio between the thickness Tr of the photoelectric conversion layer on the light receiving side and the thickness Tt of the photoelectric conversion layer on the transmission side is Tr / Tt = 10/90 to 95/5 (for example, 20 / 80/90/10) and can be selected from the range of 10/90 to 80/20 (for example, 20/80 to 75/25), preferably 30/70 to 70/30 (for example, 40/60 to 65 / 35) may be sufficient. Increasing the thickness Tr of the photoelectric conversion layer on the light receiving side can absorb incident light efficiently and increase the photoelectric conversion efficiency. In particular, it is preferable to form a photoelectric conversion layer capable of absorbing short wavelengths on the light receiving side and to increase the thickness Tr of the photoelectric conversion layer on the light receiving side.

A laminated photoelectric conversion body (laminated dye-sensitized photoelectric conversion body or laminated body) formed on a conductive substrate has a conductive layer and a photoelectric conversion layer, and an electrode (photoelectrode) constituting a photoelectric conversion element ). In particular, since a plurality of photoelectric conversion layers having different absorption lights are formed, incident light from a short wavelength region to a long wavelength region can be efficiently photoelectrically converted while having a single structure. Therefore, high conversion efficiency can be realized while the structure is simple.

[Photoelectric conversion element and manufacturing method thereof]
A photoelectric conversion element provided with a laminated photoelectric conversion body (photoelectrode) formed on a conductive substrate can be used for various applications capable of photoelectric conversion, and typically used for a solar cell (dye-sensitized solar cell). it can.

A solar cell is, for example, a laminated photoelectric conversion body formed on a conductive substrate as an electrode, a counter electrode disposed opposite to the electrode (on the photoelectric conversion layer side of the electrode), and sealed between these electrodes An electrolyte phase (or electrolyte layer). In such a photoelectric conversion element, the same process as that for producing the laminated photoelectric converter, for example, a coating composition containing a plurality of dyes having different absorption wavelength ranges or absorption peak wavelengths, A step of sequentially coating and laminating a plurality of coating compositions containing the conductive substrate, and a step of forming a laminated photoelectric conversion body in which a plurality of photoelectric conversion layers are laminated without sintering the semiconductor; It can manufacture by the method containing. The electrolyte phase (or electrolyte) is a sealant [for example, a sealant containing a thermoplastic resin (such as an ionomer resin), a thermosetting resin (such as an epoxy resin or a silicone resin)) on the periphery of both electrodes. By sealing, it is enclosed in a space or gap between both electrodes.

When the semiconductor is an n-type semiconductor, the counter electrode forms a positive electrode (the stacked body is a negative electrode), and when the semiconductor is a p-type semiconductor, the counter electrode forms a negative electrode (the stacked body is a positive electrode).

The counter electrode includes a conductive substrate and a catalyst layer (a positive electrode catalyst layer or a negative electrode catalyst layer) formed on the conductive substrate (or on the conductive layer of the conductive substrate) in the same manner as the stacked photoelectric conversion body. The conductive layer or the catalyst layer of the counter electrode is disposed so as to face the stacked photoelectric conversion body (or electrode). Note that a catalyst layer is not necessarily provided in a conductive layer having a reducing ability. The conductive substrate for the counter electrode may be a substrate in which a layer having both a conductive layer and a catalyst layer (conductive catalyst layer) is formed on a base substrate in addition to the same substrate as described above. The catalyst layer (positive electrode catalyst layer or negative electrode catalyst layer) is not particularly limited, and can be formed of a conductive metal (such as gold or platinum), carbon, or the like.

The catalyst layer (positive electrode catalyst layer or negative electrode catalyst layer) may be a non-porous layer (or non-porous layer) or a porous layer. The porous layer (porous catalyst layer) may be composed of a porous catalyst component (porous catalyst component), and is composed of a porous component (porous component) and a catalyst component supported on the porous component. Alternatively, these may be combined. That is, the porous layer (porous catalyst layer) has porosity and functions as a catalyst.

Examples of the porous catalyst component include metal fine particles (for example, platinum black), porous carbon [carbon black (carbon black aggregate) such as activated carbon, graphite, ketjen black, furnace black, acetylene black, carbon nanotube ( Carbon nanotube aggregate)) and the like. These components may be used alone or in combination of two or more. Activated carbon or the like may be used as the porous catalyst component.

Examples of the porous component include metal compound particles [e.g., particles (fine particles) of the above-described conductive metal oxide (e.g., tin-doped indium oxide)] in addition to the porous carbon. These components may be used alone or in combination of two or more. Examples of the catalyst component include a conductive metal (for example, platinum).

The shape (or form) of the porous catalyst component and the porous component is not particularly limited, and may be particulate or fibrous, and is preferably particulate. The average particle diameter of the particulate porous catalyst component and the porous component (porous particles) is, for example, 1 to 1000 μm (for example, 10 to 500 μm), preferably 30 to 300 μm (for example, 40 to 200 μm), and more preferably May be about 50 to 150 μm (for example, 70 to 100 μm). The BET specific surface area of the porous catalyst component and the porous component is, for example, 1 to 4000 m ² / g (for example, 20 to 3000 m ² / g), preferably 50 to 2000 m ² / g (for example, 100 to 1500 m ² / g). ), More preferably about 200 to 1000 m ² / g (for example, 300 to 500 m ² / g).

The porous layer (porous catalyst layer) may be a binder component, for example, a resin component [for example, a thermoplastic resin such as a cellulose derivative (such as methylcellulose); a thermosetting resin such as an epoxy resin] or the like. May be included. The ratio of the binder component is, for example, 0.1 to 50% by weight (for example, 1 to 40% by weight), preferably 2 to 30% by weight (for example, 3%) with respect to the entire porous layer (porous catalyst layer). ˜20 wt%), more preferably about 5 to 15 wt%.

The electrode (counter electrode) often includes at least a porous layer, and usually includes at least a substrate (a substrate that may be a conductive substrate) and a porous catalyst layer. An electrode (counter electrode) having a representative porous layer includes (i) a conductive substrate and a porous catalyst layer formed on the conductive substrate (or conductive layer) and composed of a porous catalyst component. Electrode (or laminate) provided, (ii) a conductive substrate, and a porous catalyst formed on the conductive substrate and containing a porous component and a catalyst component (for example, a porous component carrying the catalyst component) The electrode (or laminated body) provided with the layer etc. may be sufficient.

The thickness of the porous layer (porous catalyst layer) may be, for example, about 0.1 to 100 μm, preferably 0.5 to 50 μm, more preferably about 1 to 30 μm.

The electrolyte layer may be formed of an electrolytic solution containing an electrolyte and a solvent, or may be formed of a solid layer (or gel) containing an electrolyte. The electrolyte of the electrolytic solution is not particularly limited, and is a general-purpose electrolyte, for example, a combination of a halogen (halogen molecule) and a halide salt [for example, a combination of bromine and bromide salt, a combination of iodine and iodide salt, etc. ] Etc. are mentioned. Counter ions (cations) constituting the halide salt include metal ions [for example, alkali metal ions (for example, lithium ions, sodium ions, potassium ions, cesium ions, etc.), alkaline earth metal ions (for example, magnesium ions, Quaternary ammonium ion [tetraalkylammonium salt, pyridinium salt, imidazolium salt (eg, 1,2-dimethyl-3-propylimidazolium salt)] and the like. The electrolytes may be used alone or in combination of two or more.

Preferred electrolytes include combinations of iodine and iodide salts, particularly iodine and metal iodide salts [for example, alkali metal salts (lithium iodide, sodium iodide, potassium iodide, etc.), quaternary ammonium salts, etc. And the combination.

The solvent of the electrolytic solution is not particularly limited, and examples thereof include alcohols (for example, alkanols such as methanol, ethanol, and butanol; glycols such as ethylene glycol, diethylene glycol, and polyethylene glycol), and nitriles (acetonitrile, methoxyacetonitrile, Propionitrile, valeronitrile, 3-methoxypropionitrile, benzonitrile, etc.), carbonates (ethylene carbonate, propylene carbonate, diethyl carbonate, etc.), lactones (γ-butyrolactone, etc.), ethers (1,2-dimethoxy) Chain ethers such as ethane, dimethyl ether and diethyl ether; rings such as tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane and 4-methyldioxolane Ethers), sulfolane (such as sulfolane), sulfoxides (dimethyl sulfoxide, etc.), amides (N, N-dimethylformamide, N, N- dimethylacetamide, etc.), and water. The solvents may be used alone or in combination of two or more.

As described above, when the pH of the ionic polymer is adjusted, the pH of the ionic polymer may be adjusted in the same range as described above also in the photoelectric conversion element. From the viewpoint of such pH adjustment, a component that does not affect pH adjustment may be suitably used as the component of the electrolytic solution. For example, a neutral solvent or a non-acidic solvent (or an aprotic solvent) may be suitably used as the electrolytic solution.

In the electrolytic solution, the concentration of the electrolyte may be, for example, about 0.01 to 10M, preferably 0.03 to 8M, and more preferably about 0.05 to 5M. Further, when a halogen (iodine etc.) and a halide salt (iodide salt etc.) are combined, the ratio thereof is halogen / halide salt (molar ratio) = 1 / 0.5 to 1/100, preferably 1 / 1 to 1/50, more preferably about 1/2 to 1/30.

In addition to the electrolytes exemplified above, solid electrolytes {eg, resin components [eg, thiophene polymers (eg, polythiophene)], carbazole polymers (eg, poly (N-vinyl) Carbazole) and the like], organic solid components such as low molecular weight organic components (eg, naphthalene, anthracene, phthalocyanine, etc.); inorganic solid components such as silver iodide} and the like. These components may be used alone or in combination of two or more.

The solid layer is a solid layer in which the electrolyte or electrolytic solution is held on a gel base material [for example, thermoplastic resin (polyethylene glycol, polymethyl methacrylate, etc.), thermosetting resin (epoxy resin, etc.), etc.]. May be.

Although the photoelectric conversion element having such a structure is a single element, it can absorb a wide wavelength range from a short wavelength range to a long wavelength range and efficiently perform photoelectric conversion, and is suitable as a solar cell. In addition, compared with a tandem photoelectric conversion element in which a plurality of cells are arranged, the photoelectric conversion efficiency can be improved with a very simple structure. Furthermore, since no electrode substrate, electrolyte, or the like is interposed between photoelectric conversion layers having different absorption wavelengths, there is little loss of light absorption, members such as expensive conductive substrates can be reduced, and photoelectric conversion elements can be manufactured at low cost. .

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(Example 1)
Anionic polymer (5% by weight Nafion dispersion (manufactured by DuPont, “nafion DE520”, ion exchange capacity 0.9 meq / g, pH (25 ° C.) = 1, occupied area per molecule about 0.024 nm ² )) Was diluted with isopropyl alcohol twice and neutralized with a 5 wt% aqueous lithium hydroxide solution (prepared by dissolving lithium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.) in ion-exchanged water) to give 2.5 wt. % Nafion dispersion was prepared.

After adding and dissolving 0.9 parts by weight of “N719” dye (solaronix, molecular weight: 1188.57, occupied area of about 1 nm ² per molecule) in 200 parts by weight of this 2.5% by weight Nafion dispersion. , 30 parts by weight of titanium oxide particles (mixture of Nippon Aerosil Co., Ltd., “P25”, average primary particle size 30 nm, specific surface area about 40 m ² / g, anatase type / rutile type = 80/20 (weight ratio)) It added and mixed and the photoelectric conversion ink 1 (ink for short wavelength absorption) was prepared.

Further, in place of the “N719” dye, the “N749” dye (manufactured by solaronix, molecular weight 1188.57, occupied area of about 1 nm ² per molecule) was used in the same manner as described above, and the photoelectric conversion ink 2 (for long wavelength absorption) Ink) was prepared.

The obtained photoelectric conversion ink 1 was applied to the ITO layer side of a glass substrate with ITO (Geomatec, size 12 mm × 25 mm, surface resistance 10Ω / □) by a squeegee method, and then dried at 90 ° C. in the atmosphere to perform photoelectric conversion. Layer 1 (short wavelength absorption layer) was formed. Subsequently, the photoelectric conversion ink 2 was applied on the photoelectric conversion layer 1 by the squeegee method, and then dried in the atmosphere at 90 ° C. to form the photoelectric conversion layer 2 (long wavelength absorption layer). The laminated photoelectric conversion layer is cut into a predetermined size (4 mm × 4 mm) to remove an excess film, and a laminated photoelectric conversion layer having a thickness of 10 μm (photoelectric conversion layer 1 thickness 6 μm, photoelectric conversion layer 2 thickness 4 μm). Formed.

As a counter electrode for the laminated photoelectric conversion layer, a platinum thin film (electrode) having a thickness of 0.003 μm was formed on the ITO layer of a glass substrate with ITO (manufactured by Geomatic Co., Ltd., 10Ω / □) by a sputtering method.

Spacers (Mitsui / DuPont Polychemical Co., Ltd., “High Milan”) are placed around both glass substrates, and the photoelectric conversion layer side of the laminated photoelectric conversion layer is opposed to the counter electrode platinum thin film. A space (or a space sealed with a sealing material) formed between them was filled with an electrolytic solution, and the electrolytic solution injection port was closed with an epoxy resin to produce a dye-sensitized solar cell. The electrolyte solution was an acetonitrile solution containing 0.05M iodine, 0.1M lithium iodide, 0.5M 1,2-dimethyl-3-propylimidazolium iodide, 0.5M 4-tert-butylpyridine. Using.

(Comparative Example 1)
The photoelectric conversion ink 1 prepared in Example 1 (“N719” dye, for short wavelength absorption) was applied to the ITO layer side of the glass substrate with ITO by the squeegee method, and then dried in the atmosphere at 90 ° C. to obtain the photoelectric conversion layer 1. (Short wavelength absorption layer) was formed, the photoelectric conversion layer was cut in the same manner as in Example 1, and a dye-sensitized solar cell having a photoelectric conversion layer having a thickness of 10 μm (thickness of photoelectric conversion layer 1 of 10 μm) was obtained.

(Comparative Example 2)
A dye-sensitized solar cell was prepared in the same manner as in Comparative Example 1 except that the photoelectric conversion ink 2 prepared in Example 1 (“N749” dye, for long wavelength absorption) was used instead of the photoelectric conversion ink 1 in Comparative Example 1. Was made.

(Example 2)
In Example 1, MK-2 dye (manufactured by Soken Chemical Co., Ltd.) was used instead of N719 dye, and the thickness of the photoelectric conversion layer 1 was 3 μm and the thickness of the photoelectric conversion layer 2 was 7 μm. In the same manner as above, a dye-sensitized solar cell was produced.

The dye-sensitized solar cells obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to AM 1.5, 100 mW / mm using a solar simulator (“XES-301S + EL-100” manufactured by Mitsunaga Electric Co., Ltd.). Evaluation was performed under conditions of cm ² and 25 ° C. The output characteristics of the obtained dye-sensitized solar cell are shown in FIG.

As is clear from FIG. 1, when a stacked photoelectric conversion layer is formed, the photoelectric conversion efficiency can be greatly improved.

(Example 3)
In Example 1, instead of the glass substrate with ITO, a polyethylene terephthalate (PET) film with ITO (manufactured by Aldrich, size 30 × 50 mm, thickness of ITO layer 0.12 μm) was used in the same manner as in Example 1. When a dye-sensitized solar cell was produced, the same output characteristics as in Example 1 were obtained.

The laminated photoelectric conversion body (laminated body) of the present invention has a plurality of photoelectric conversion layers having different absorption wavelengths, and is useful for forming a photoelectric conversion element (such as a dye-sensitized solar cell). Furthermore, since a stacked photoelectric conversion body (laminated body) can be formed by coating without sintering, a photoelectric conversion layer or a photoelectric conversion element can be easily formed.

Claims

A laminated photoelectric conversion body in which photoelectric conversion layers including a semiconductor, an ionic polymer, and a dye are stacked, wherein the stacked photoelectric conversion body is formed by stacking a plurality of the photoelectric conversion layers and is included in each photoelectric conversion layer Laminated photoelectric converters having different absorption wavelength ranges or absorption peak wavelengths.
The laminated photoelectric conversion body according to claim 1, wherein a photoelectric conversion layer containing a dye capable of absorbing a short wavelength region is formed on the light receiving side, and a photoelectric conversion layer containing a dye capable of absorbing a long wavelength region is formed on the transmission side. .
In the plurality of photoelectric conversion layers formed by coating, the light-receiving side photoelectric conversion layer contains a first dye having an absorption peak wavelength at 300 to 600 nm, and the photoelectric conversion layer opposite to the light-receiving side has a thickness of 550 to 800 nm. 3. The laminated photoelectric converter according to claim 1, comprising a second dye having an absorption peak wavelength, wherein the absorption peak wavelength of the first dye is 10 nm or more shorter than the absorption peak wavelength of the second dye.
The semiconductor contains at least one selected from titanium oxide nanoparticles, zinc oxide nanoparticles, and tin oxide nanoparticles, the ionic polymer contains a fluorine-containing resin having a sulfo group, and the proportion of the ionic polymer is 100 parts by weight of the semiconductor The laminated photoelectric conversion body according to any one of claims 1 to 3, wherein the amount is 1 to 100 parts by weight based on the weight.
A set of a coating composition for forming a plurality of photoelectric conversion layers on a conductive substrate, comprising a semiconductor, an ionic polymer, and a dye, wherein the plurality of coating compositions each have a different absorption wavelength range or A set of a plurality of coating compositions containing a dye having an absorption peak wavelength.
In a method of applying a plurality of coating compositions containing a semiconductor, an ionic polymer, and a dye to a conductive substrate to form a photoelectric conversion layer, the absorption wavelength range or absorption peak wavelength of the dye contained in each coating agent is mutually A method for producing a laminated photoelectric converter without coating the plurality of coating compositions sequentially on a conductive substrate, laminating and sintering.
A photoelectric conversion element comprising the laminated photoelectric conversion body according to any one of claims 1 to 4.
The laminated photoelectric conversion body according to any one of claims 1 to 4, formed on a conductive substrate as an electrode, a counter electrode disposed to face the electrode, and an electrolyte sealed between these electrodes The photoelectric conversion element of Claim 7 provided with the phase.
A method for producing a photoelectric conversion element comprising a photoelectric conversion layer formed on a conductive substrate as an electrode, a counter electrode disposed opposite to the electrode, and an electrolyte phase sealed between the electrodes. A plurality of coating compositions containing a semiconductor, an ionic polymer, and a dye and having different absorption wavelength ranges or absorption peak wavelengths of the dye contained in each coating agent are sequentially coated and laminated on the conductive substrate. The manufacturing method of a photoelectric conversion element including the process and the process of forming the laminated photoelectric conversion body by which the several photoelectric converting layer was laminated | stacked, without making it sinter.