JP2010170775A - Photoelectric conversion element and solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion element with high photoelectric conversion efficiency. <P>SOLUTION: In the photoelectric conversion element provided with a semiconductor layer, a charge transport layer, and counter electrodes on a conductive support body, the semiconductor layer has oxide semiconductor particles having absorbed dyes dispersed in a p-type semiconductor polymer compound, and the semiconductor layer contains an n-type semiconductor compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion element and a solar cell, and more particularly to a dye-sensitized photoelectric conversion element having a semiconductor layer containing a dye and an n-type semiconductor compound and a solar cell using the same.

  In recent years, the use of sunlight, which is infinite and does not generate harmful substances, has been energetically studied. What is currently put into practical use as solar energy, which is a clean energy source, includes residential single crystal silicon, polycrystalline silicon, amorphous silicon, and inorganic solar cells such as cadmium telluride and indium copper selenide. .

  However, the disadvantages of these inorganic solar cells are that, for example, silicon-based solar cells are required to have a very high purity. Naturally, the purification process is complicated, the number of processes is large, and the production cost is high.

  On the other hand, many solar cells using organic materials have been proposed. As an organic solar cell, a Schottky photoelectric conversion element that joins a p-type organic semiconductor and a metal having a low work function, a p-type organic semiconductor and an n-type inorganic semiconductor, or a p-type organic semiconductor and an electron-accepting organic compound are joined. There are heterojunction photoelectric conversion elements, and organic semiconductors used are synthetic dyes and pigments such as chlorophyll and perylene, conductive polymer materials such as polyacetylene, or composite materials thereof. These are thinned by a vacuum deposition method, a casting method, a dipping method, or the like to form a battery material. Although organic materials have advantages such as low cost and easy area enlargement, there are many problems that the photoelectric conversion efficiency is as low as 1% or less, and the durability is poor.

  Under such circumstances, a solar cell exhibiting good characteristics has been reported by Dr. Gretzell of Switzerland (see, for example, Non-Patent Document 1). The proposed battery is a dye-sensitized solar cell, which is a wet solar cell using a titanium oxide porous thin film spectrally sensitized with a ruthenium complex as a working electrode. In addition, in order to improve the electrical conductivity by improving the contact of the oxide semiconductor, a process of bonding and joining the semiconductor particles is performed. The advantage of this method is that it is not necessary to purify an inexpensive oxide semiconductor such as titanium oxide to high purity, and therefore, it is inexpensive and the available light extends over a wide visible light region, so that a solar having a large amount of visible light components. It is that light can be effectively converted into electricity.

  A cell using a flexible substrate such as plastic can also be manufactured (see Non-Patent Document 2 and Patent Document 1). However, in the case of a photoelectric conversion element using a flexible substrate, in order to improve the electrical conductivity by improving the contact of the semiconductor particles, if the treatment for bonding and bonding the semiconductor particles contained in the semiconductor layer is performed, There is a problem that the conversion efficiency is lowered due to cracking or peeling of the semiconductor layer due to bending or the like.

  The occurrence of this problem can be suppressed by reducing the thickness of the semiconductor layer. However, when the thickness is reduced, the light collecting power is reduced and it is difficult to obtain sufficient conversion efficiency.

JP 2002-231326 A

B. O'Regan, M.M. Gratzel, Nature, 353, 737 (1991) T.A. Miyasaka, Y. et al. Kijitori, T .; N. Murakami, M .; Kimura, S .; Uegusa, Chem. Lett. , 31, 1250 (2002)

  The present invention has been made in view of the above-described problems, and an object of the present invention is to use a photoelectric conversion element that has high photoelectric conversion efficiency and does not cause cracking or peeling when bent even if the semiconductor layer is thick. It is to provide a solar cell.

  The above object of the present invention is achieved by the following configurations.

  1. In the photoelectric conversion element having a semiconductor layer, a charge transport layer, and a counter electrode on a conductive support, the semiconductor layer has oxide semiconductor particles adsorbed with a dye dispersed in a p-type semiconductor polymer compound, And the said semiconductor layer contains an n-type semiconductor compound, The photoelectric conversion element characterized by the above-mentioned.

  2. 2. The photoelectric conversion element as described in 1 above, wherein the n-type semiconductor compound is adsorbed to the oxide semiconductor particles together with a dye.

  3. A solar cell comprising the photoelectric conversion element as described in 1 or 2 above.

  According to the present invention, it is possible to provide a photoelectric conversion element that has high photoelectric conversion efficiency and that does not break or peel when the semiconductor layer is bent even when it is thick, and a solar cell using the photoelectric conversion element.

It is sectional drawing which shows an example of the photoelectric conversion element of this invention. It is sectional drawing which shows another example of the photoelectric conversion element of this invention.

  In a dye-sensitized solar cell, in order to improve electrical conductivity by improving contact between semiconductor particles, a process of bonding and bonding semiconductor particles is performed. However, when a flexible substrate is used, stress relaxation is less likely to occur when the above treatment is performed. Therefore, when the semiconductor layer is thickened, the strength against bending is reduced. There was a problem that efficiency decreased. In order to solve this problem, when the semiconductor layer is thinned, the light collecting ability is lowered, and there is a problem that high photoelectric conversion efficiency cannot be obtained. Therefore, in order to achieve both prevention of cracking and peeling of the semiconductor layer when bent and thickening of the semiconductor layer, it is necessary to obtain sufficient electrical conductivity without performing bonding / bonding treatment between the semiconductor particles. .

  Therefore, by dispersing the oxide semiconductor particles adsorbed with the dye in the p-type semiconductor polymer compound and further containing the n-type semiconductor compound, high electrical conductivity is achieved compared to the case where there is no n-type semiconductor compound. And it discovered that a high photoelectric conversion efficiency was obtained, without a crack and peeling, when it bends even with a thick film. The n-type semiconductor compound is preferably adsorbed on the oxide semiconductor particles together with the dye.

  The mechanism by which such an effect is expressed is estimated as follows.

  Since the n-type semiconductor compound is adsorbed to or close to the oxide semiconductor particles together with the dye, the dye absorbs light, and the electrons generated by excitation are oxide semiconductor particles such as titanium oxide, the n-type semiconductor compound, and then the conductive support. To the counter electrode to reduce the charge transport agent such as an aromatic amine derivative in the charge transport layer. On the other hand, the dye that has moved the electrons to the oxide semiconductor particles is an oxidant, but when the electrons are supplied from the counter electrode via the charge transport layer, it is reduced and returned to its original state. The charge transporting agent such as an aromatic amine derivative in the charge transporting layer is oxidized and returns to a state where it can be reduced again by electrons supplied from the counter electrode. As a result, a photocurrent is observed.

  When the n-type semiconductor compound is not present in the semiconductor layer, some of the electrons generated by light absorption cannot be transferred to the conductive support, or are transferred to the oxidized p-type semiconductor and deactivated. It is estimated to be. Accordingly, the photocurrent is reduced. In addition, when the n-type semiconductor compound is adsorbed on the oxide semiconductor particles, the deactivation can be effectively suppressed because the n-type semiconductor compound is present in the vicinity of the oxide semiconductor particles.

  Hereinafter, the present invention will be described in detail.

<< Photoelectric conversion element >>
The photoelectric conversion element of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of the photoelectric conversion element of the present invention. As shown in FIG. 1, the photoelectric conversion element of the present invention comprises a substrate 1, a transparent conductive film 2, a semiconductor layer 8, a charge transport layer 9, a counter electrode 10, and the like. The semiconductor layer 8 contains a dye 4, oxide semiconductor particles 5, an n-type semiconductor compound 6, and a p-type semiconductor polymer compound 7.

  The photoelectric conversion element of this invention is formed with the following structures. An insulating layer 3 is formed on a substrate 1 (also referred to as a conductive support) to which a transparent conductive film 2 is attached, if necessary, and then an oxide semiconductor particle 5 having a dye 4 adsorbed on its surface, an n-type semiconductor compound 6 And the semiconductor layer 8 which has the p-type semiconductor polymer compound 7 is formed. The charge transport layer 9 is provided on the semiconductor layer 8, and the counter electrode 10 is provided thereon. A terminal is attached to the transparent conductive film 2 and the counter electrode 10 to extract a photocurrent. FIG. 2 shows an example of a cross-sectional view of an element provided with the insulating layer 3.

[Semiconductor layer]
In the semiconductor layer according to the present invention, oxide semiconductor particles adsorbed with a dye are dispersed in a p-type semiconductor polymer compound and contain an n-type semiconductor compound. The n-type semiconductor compound is preferably adsorbed together with the pigment on the oxide semiconductor particles.

(Dye)
In the present invention, a dye is adsorbed on the oxide semiconductor particles. When the sensitization treatment is performed using a dye, the dye may be used alone or in combination.

  From the viewpoint of efficient injection of charges into the oxide semiconductor particles, the dye preferably has a carboxyl group. Moreover, the pigment | dye which has a preferable carboxyl group for this invention, and another pigment | dye can also be used together. As the dye that can be used in combination, any dye can be used as long as it can spectrally sensitize the oxide semiconductor particles according to the present invention. In order to make the wavelength range of photoelectric conversion as wide as possible and increase the photoelectric conversion efficiency, it is preferable to mix two or more kinds of dyes. Moreover, the pigment | dye mixed and the ratio can be selected so that it may match with the wavelength range and intensity distribution of the target light source.

  In particular, when the use of the photoelectric conversion element of the present invention is a solar cell described later, two or more types having different absorption wavelengths can be used so that sunlight can be effectively used by widening the wavelength range of photoelectric conversion as much as possible. It is preferable to use a mixture of dyes.

  Among the dyes used in combination, metal complex dyes, phthalocyanine dyes, porphyrin dyes, and polymethine dyes are preferably used from the comprehensive viewpoints such as photoelectron transfer reaction activity, light durability, and photochemical stability.

  Examples of the dye that can be used in combination with the preferred dye having a carboxyl group in the present invention include, for example, US Pat. Nos. 4,684,537, 4,927,721, 5,084, 365, 5,350,644, 5,463,057, 5,525,440, JP-A-7-249790, JP-A-2000-150007 And the like.

  In order to adsorb the dye to the oxide semiconductor particles, a general method is to dissolve the dye in an appropriate solvent (ethanol or the like) and immerse the well-dried oxide semiconductor particles in the solution for a long time.

  When sensitizing by using a combination of a plurality of dyes or using a dye other than the dye having a carboxyl group preferable for the present invention, a mixed solution of each dye may be prepared and used. It is also possible to prepare a solution for each dye and immerse in each solution in order. When preparing different solutions for each dye and immersing in each solution in order, the effect described in the present invention can be obtained regardless of the order in which the dye is included in the oxide semiconductor particles. Can do. Alternatively, the oxide semiconductor particles in which a dye is adsorbed alone may be mixed.

  Specific examples of the dye are shown below, but the present invention is not limited thereto.

(Oxide semiconductor particles)
In the photoelectric conversion element of the present invention, oxide semiconductor particles include oxides of compounds having elements of Group 3 to Group 5 and Group 13 to Group 15 of the periodic table (also referred to as element periodic table). Can be used.

Specific examples include TiO ₂ , ZrO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , Ta ₂ O _{5 and the} like, but preferably used are TiO ₂ , ZnO, SnO ₂ , Fe ₂ O ₃ , WO ₃ and Nb ₂ O ₅ are TiO ₂ or SnO ₂ more preferably used, but TiO ₂ is particularly preferably used among them.

The oxide semiconductor particles used in the present invention may be used in combination with a plurality of oxide semiconductors described above. For example, several kinds of the above-described metal oxides can be used in combination, and 20% by mass of titanium nitride (Ti ₃ N ₄ ) may be mixed and used in the titanium oxide semiconductor. In addition, J.H. Chem. Soc. Chem. Commun. 15 (1999). At this time, when adding a component other than the metal oxide as the oxide semiconductor particle, the mass ratio of the additional component to the metal oxide semiconductor is preferably 30% or less.

  The oxide semiconductor particles preferably have a finer primary particle diameter, and the primary particle diameter is preferably 1 to 5,000 nm, more preferably 2 to 50 nm. Oxide semiconductor particles in which oxide semiconductor particles are dispersed in a solvent containing a pigment are dispersed in the form of primary particles.

(N-type semiconductor compound)
In general, p-type and n-type are classified as p-type compounds that are mainly holes that contribute to electrical conduction by semiconductor compounds, and n-type compounds that are mainly electrons. The n-type semiconductor compound of the present invention refers to a semiconductor compound other than the oxide semiconductor particles.

  Examples of n-type semiconductor compounds include fullerene, octaazaporphyrin, p-type semiconductor perfluoro compounds (perfluoropentacene, perfluorophthalocyanine, etc.), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetracarboxylic acid Examples include anhydrides, aromatic carboxylic acid anhydrides such as perylenetetracarboxylic acid diimide, and compounds containing the imidized product thereof as a skeleton.

  Of these, fullerene-containing compounds are preferred. Fullerene-containing compounds include fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C84, fullerene C240, fullerene C540, mixed fullerene, fullerene nanotubes, multi-walled nanotubes, single-walled nanotubes, nanohorns (conical), etc. The compound which has is mentioned. As the fullerene-containing compound, a compound (derivative) having fullerene C60 as a skeleton is preferable.

  The fullerene-containing polymers are roughly classified into polymers in which fullerene is pendant from a polymer main chain and polymers in which fullerene is contained in the polymer main chain. Fullerene is contained in the polymer main chain. Are preferred. This is because a polymer in which fullerene is pendant has a branched structure, that is, the polymer cannot be packed with high density when solidified, and as a result, high mobility can be obtained. It is presumed that it is due to disappear.

  Specific examples of the n-type semiconductor compound are shown below, but the present invention is not limited thereto.

(P-type semiconductor polymer compound)
Examples of the p-type semiconductor polymer compound include aromatic amine derivative polymers having excellent hole transport ability. As the aromatic amine derivative polymer, it is particularly preferable to use a triphenyldiamine derivative polymer. The triphenyldiamine derivative polymer is particularly excellent in hole transport ability among aromatic amine derivative polymers. The weight average molecular weight of the p-type semiconductor polymer compound is preferably 7,000 to 200,000. The weight average molecular weight can be measured by gel permeation chromatography.

  Specific examples of the aromatic tertiary amine derivative polymer include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′-bis. (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis ( 4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolylamino) Phenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N'- Di (4-Me N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether; 4,4′-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenyl) Vinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and also two fused aromatic rings described in US Pat. No. 5,061,569. In the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308688 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA), etc., in which three triphenylamine units described in the above are linked in a starburst type Is mentioned.

  Examples of the p-type semiconductor polymer compound other than the aromatic amine derivative include a thiophene derivative polymer, a pyrrole derivative polymer, and a stilbene derivative polymer.

  Specific examples of the p-type semiconductor polymer compound are shown below, but the present invention is not limited thereto.

(Formation of semiconductor layer)
In the semiconductor layer according to the present invention, oxide semiconductor particles adsorbed with a dye are dispersed in a p-type semiconductor polymer compound and contain an n-type semiconductor compound. At this time, the n-type semiconductor compound is preferably adsorbed to the oxide semiconductor particles together with the dye. At this time, the addition concentration of the oxide semiconductor particles adsorbed with the dye to the p-type semiconductor polymer is preferably 20 to 500% by mass, more preferably 30 to 200% by mass. When the concentration of the p-type semiconductor polymer is high, the bendability becomes stronger, and when the concentration of the oxide semiconductor particles is high, the amount of adsorbable dye increases, resulting in high conversion efficiency. Accordingly, when assuming use in a more fragile environment, for example, a low temperature environment such as 10 ° C. or less, the concentration of the oxide semiconductor particles added to the p-type semiconductor polymer is in the range of 20 to 500% by mass. Preferably there is.

  In order to obtain oxide semiconductor particles in which both the dye and the n-type semiconductor compound are adsorbed, the dye and the n-type semiconductor compound as described above are dissolved in an appropriate solvent, and the oxide semiconductor particles are dispersed in the solution, followed by filtration. -After redispersion is repeated several times, drying is performed to obtain oxide semiconductor particles adsorbed with the dye and the n-type semiconductor compound. When the n-type semiconductor compound is adsorbed to the oxide semiconductor particles together with the dye, the molar concentration ratio between the n-type semiconductor compound and the dye is preferably n-type semiconductor compound: dye = 5: 1 to 1:20. .

  The solvent used for dissolving the dye and the n-type semiconductor compound is not particularly limited as long as it can dissolve and does not dissolve or react with the oxide semiconductor particles. However, in order to prevent the moisture and gas dissolved in the solvent from interfering with the sensitization treatment such as adsorption of the dye and the n-type semiconductor compound, it is preferable to perform deaeration and distillation purification in advance.

  Solvents preferably used include alcohol solvents such as methanol, ethanol, n-propanol, and t-butyl alcohol, ketone solvents such as acetone and methyl ethyl ketone, and ether solvents such as diethyl ether, diisopropyl ether, tetrahydrofuran, and 1,4-dioxane. Solvents, nitrile solvents such as acetonitrile and propionitrile, halogenated hydrocarbon solvents such as methylene chloride and 1,1,2-trichloroethane, and aromatic solvents such as toluene, and mixed solvents may be used. Particularly preferred are ethanol, t-butyl alcohol, acetonitrile, tetrahydrofuran, toluene and a mixed solvent thereof.

  Thereafter, the oxide semiconductor particles are dispersed in the p-type semiconductor polymer compound as described above, and the oxide semiconductor particles dispersed in the p-type semiconductor polymer compound are coated on a conductive support. A semiconductor layer is formed. A surfactant and a viscosity modifier (polyhydric alcohol such as polyethylene glycol) can be added to the coating solution as necessary. The range of the oxide semiconductor particle concentration in the solvent is preferably 0.1 to 70% by mass, and more preferably 0.1 to 30% by mass.

  As another method, the oxide semiconductor particles are immersed in a dye solution to adsorb the dye, and the oxide semiconductor particles adsorbed with the dye and the n-type semiconductor compound are dispersed in the p-type semiconductor polymer compound. Here, the n-type semiconductor compound is preferably 0.1 to 50% by mass with respect to the oxide semiconductor fine particles. Then, you may form a semiconductor layer by apply | coating the oxide semiconductor particle disperse | distributed in the said p-type semiconductor polymer compound on an electroconductive support body. The time for immersing the oxide semiconductor particles in the solution containing the dye sufficiently advances the adsorption and the like, sufficiently sensitizes the oxide semiconductor, and the decomposition product generated by the decomposition of the dye in the solution is the dye. From the viewpoint of suppressing the hindering of the adsorption, it is preferably 1 to 48 hours at 25 ° C., more preferably 3 to 24 hours. However, the immersion time is a value at 25 ° C., and this is not the case when the temperature condition is changed. In soaking, the solution containing the pigment may be heated to a temperature that does not boil as long as the pigment does not decompose. A preferable temperature range is 10 to 100 ° C., more preferably 25 to 80 ° C., but this is not the case when the solvent boils in the temperature range as described above.

  In the photoelectric conversion element of the present invention, a semiconductor layer in which a dye and an n-type semiconductor compound are adsorbed on the above-described oxide semiconductor particles and a counter electrode are disposed on a conductive support so as to face each other via a charge transport layer. Become. Hereinafter, the substrate, the charge transport layer, and the counter electrode will be described.

(substrate)
The substrate used for the photoelectric conversion element of the present invention and the solar cell of the present invention (also referred to as a conductive support) is made of a conductive material such as a metal plate, or a non-conductive material such as a glass plate or a plastic film. A structure provided with a conductive substance can be used. Examples of materials used for the conductive support include metals (for example, platinum, gold, silver, copper, aluminum, rhodium, indium) or conductive metal oxides (for example, indium-tin composite oxide, fluorine for tin oxide) And carbon). The thickness of the conductive support is not particularly limited, but is preferably 0.3 to 5 mm.

  Further, the conductive support is preferably substantially transparent, and substantially transparent means that the light transmittance is 10% or more, more preferably 50% or more, Most preferably, it is 80% or more. In order to obtain a transparent conductive support, it is preferable to provide a conductive layer made of a conductive metal oxide on the surface of a glass plate or a plastic film. When a transparent conductive support is used, light is preferably incident from the support side.

The conductive support preferably has a surface resistance of 50 Ω / cm ² or less, and more preferably 10 Ω / cm ² or less.

(Charge transport layer)
The charge transport layer is a layer having a function of rapidly reducing the oxidized oxidant and transporting holes injected at the interface with the dye to the counter electrode.

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

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

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

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

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

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

  Examples of charge transport agents other than aromatic amine derivatives include thiophene derivatives, pyrrole derivatives, stilbene derivatives, and the like.

  Specific examples of the charge transfer agent are shown below, but the present invention is not limited thereto.

  The charge transport layer is formed by applying the charge transport agent or the above-described p-type semiconductor polymer compound. Or it forms by apply | coating or filling the dispersion of the said redox electrolyte.

(Counter electrode)
The counter electrode used in the present invention will be described.

  The counter electrode only needs to have conductivity, and any conductive material can be used, but a metal thin film having good contact with the charge transport layer or a metal supported on a conductive support. It is preferable.

  In addition, when a redox electrolyte dispersion is used as the charge transport layer, it is preferable to use a dispersion having a catalytic ability to cause redox ion oxidation-reduction reaction at a sufficiently high rate. Examples of such a material include a platinum electrode, a surface of the conductive material subjected to platinum plating or platinum deposition, rhodium metal, ruthenium metal, ruthenium oxide, and carbon.

《Solar cell》
The solar cell of the present invention will be described.

  The solar cell of the present invention has a structure in which the optimum design and circuit design for sunlight are performed as one aspect of the photoelectric conversion element of the present invention, and the optimum photoelectric conversion is performed when sunlight is used as a light source. Have. That is, it has a structure in which sunlight can be irradiated to the dye-sensitized oxide semiconductor particles. When configuring the solar cell of the present invention, it is preferable that the semiconductor layer, the charge transport layer, and the counter electrode are housed in a case and sealed, or the whole is resin-sealed.

  When the solar cell of the present invention is irradiated with sunlight or electromagnetic waves equivalent to sunlight, the dye adsorbed on the oxide semiconductor particles is excited by absorbing the irradiated light or electromagnetic waves. Electrons generated by excitation move to the counter electrode via the oxide semiconductor particles, the n-type semiconductor compound, and then the conductive support, and reduce a charge transport agent such as an aromatic amine derivative in the charge transport layer. On the other hand, the dye that has moved the electrons to the oxide semiconductor particles is an oxidant, but when the electrons are supplied from the counter electrode via the charge transport layer, it is reduced and returned to its original state. The charge transporting agent such as an aromatic amine derivative in the charge transporting layer is oxidized and returns to a state where it can be reduced again by electrons supplied from the counter electrode. In this way, electrons flow, and a solar cell using the photoelectric conversion element of the present invention can be configured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example [Production of Photoelectric Conversion Element 1; Present Invention]
(Formation of semiconductor layer)
As a conductive support for forming one electrode of the photoelectric conversion element, ITO is supported as a conductive film on a polyethylene naphthalate (PEN) having a film thickness of 125 μm, and a conductive support (ITO / 10) having a surface resistance of 10Ω / □. PEN support) was prepared. A titanium oxide thin film was supported on this conductive support by a sputtering method to form a short circuit prevention layer (insulating layer).

Next, a semiconductor layer coating solution obtained by ultrasonically dispersing 10 g of titanium oxide particles A adsorbed with the dye A-1 and the n-type semiconductor compound B-1 in a 130 g toluene solution of 10 g of the p-type semiconductor polymer compound C-1, After apply | coating to a conductive support body by the doctor blade method, it dried at room temperature and atmospheric pressure for 1 hour, and also dried at 70 degreeC and 10 < ^-5 > atm (1.01 Pa) for 1 hour, and the semiconductor layer was formed. The film thickness of the semiconductor layer was 30 μm.

(Method for preparing titanium oxide particles A adsorbed with Dye A-1 and n-type semiconductor compound B-1)
200 ml of a solution obtained by dissolving Dye A-1 (5 × 10 ⁻⁴ mol / l) and n-type semiconductor compound B-1 (1 × 10 ⁻⁴ mol / l) in a THF / toluene mixture (volume ratio 1/1) In addition, 20 g of titanium oxide particles (volume average particle size 25 μm, anatase-type titanium oxide) are dispersed at 20 ° C. for 4 hours, filtered, and then dispersed in 500 ml of a THF / toluene mixture (volume ratio 1/1) and filtered. Was repeated twice and dried to obtain titanium oxide particles adsorbed with the dye A-1 and the n-type semiconductor compound B-1.

(Formation of charge transport layer)
On the semiconductor layer obtained above, a 1% by mass toluene suspension of p-type semiconductor polymer compound C-1 as a charge transport agent was applied by spin coating. Then, after air-drying for 20 minutes at room temperature and in the atmosphere, vacuuming was performed for 10 minutes to form a charge transport layer, and a laminate in which a conductive support, a semiconductor layer, and a charge transport layer were laminated in this order was obtained.

(Preparation of counter electrode)
Pt was supported on the ITO / PEN support by sputtering to produce a counter electrode.

(Preparation of photoelectric conversion element)
The produced Pt-supported ITO / PEN counter electrode was stacked on the laminate, and adhered using an ultraviolet curable resin to produce a photoelectric conversion element 1.

[Preparation of Photoelectric Conversion Element 2; Present Invention]
In the production of the photoelectric conversion element 1, the photoelectric conversion element 2 was produced in the same manner except that the formation of the semiconductor layer was changed as follows.

(Formation of semiconductor layer)
Dye A-1 was dissolved in a THF / toluene mixture (volume ratio 1/1) to prepare 200 ml of a 5 × 10 ⁻⁴ mol / l solution. Oxide semiconductor particles (titanium oxide P-25 manufactured by Degussa) are immersed in this solution for 4 hours to adsorb the dye A-1, and then washed with a THF / toluene mixture (volume ratio 1/1) and dried. did. 10 g of the obtained oxide semiconductor particles and 1 g of n-type semiconductor compound B-2 were ultrasonically dispersed in a 130 g toluene solution of 10 g of p-type semiconductor polymer compound C-1 to prepare a semiconductor layer coating solution. This coating solution is applied to a conductive support (ITO / PEN support) having an insulating layer formed thereon by a doctor blade method, followed by drying at room temperature and atmospheric pressure for 1 hour, and further drying at room temperature and under vacuum for 1 hour. Thus, a semiconductor layer was formed. The film thickness of the semiconductor layer was 30 μm.

[Preparation of Photoelectric Conversion Elements 3 to 8; Present Invention]
In the production of the photoelectric conversion element 1, photoelectric conversion elements 3 to 8 were produced in the same manner except that the types of the dye, the n-type semiconductor compound, the p-type semiconductor polymer compound and the charge transfer agent were changed as shown in Table 1. .

[Preparation of Photoelectric Conversion Elements 9, 10; Present Invention]
In the production of the photoelectric conversion element 1, in the photoelectric conversion element 9, the titanium oxide particles A adsorbed with the dye A-1 and the n-type semiconductor compound B-1 were changed to 2 g and the p-type semiconductor polymer compound C-1 was changed to 10 g. In the photoelectric conversion element 10, except that the titanium oxide particles A adsorbed with the dye A-1 and the n-type semiconductor compound B-1 were changed to 35 g and the p-type semiconductor polymer compound 7g, the photoelectric conversion element 9, 10 was produced.

[Production of Photoelectric Conversion Elements 11 and 12; Comparative Example]
In the production of the photoelectric conversion element 1, photoelectric conversion elements 11 and 12 were produced in the same manner except that the formation of the semiconductor layer was changed as follows.

(Formation of semiconductor layer)
Titanium tetraisopropoxide was dissolved in 2-propanol to 1 mol / l. Next, acetic acid (additive) and distilled water were added to this solution. The mixing ratio of acetic acid and titanium tetraisopropoxide is 1: 1 (molar ratio), and the mixing ratio of distilled water and titanium tetraisopropoxide is 1: 1 (molar ratio). I did it. Thereafter, titanium oxide P-25 (manufactured by Degussa) was mixed with this solution. Further, this suspension was diluted 2-fold with 2-propanol. Thereby, a sol solution (semiconductor layer material) was prepared. The content of the titanium oxide powder in the sol liquid was 3% by mass. The obtained sol solution (semiconductor layer material) was dropped (coating method) onto a conductive support (ITO / PEN support) on which an insulating layer was placed on a hot plate heated to 140 ° C. and dried. By performing an operation on a heated hot plate, the titanium oxide fine particles are bonded to each other. In the photoelectric conversion elements 11 and 12, this operation was repeated 10 times and 3 times, respectively, and laminated. As a result, titanium oxide layers having an average thickness of 25 μm and 2.5 μm were obtained. The obtained laminate was immersed in a 5 × 10 ⁻⁴ mol / l THF / toluene mixture (volume ratio 1/1) of the dye A-1 for 4 hours to adsorb the dye A-1, and then THF. / Toluene mixture (volume ratio 1/1) washed and dried.

  Table 1 shows the configurations of the photoelectric conversion elements 1 to 12.

[Evaluation of photoelectric conversion element]
(Power generation characteristics)
Using the solar simulator (trade name; WXS-85-H type, manufactured by Wacom Denso Co., Ltd.), the produced photoelectric conversion element was 100 mW / cm ² from a xenon lamp passed through an AM filter (AM-1.5). This was done by irradiating simulated sunlight. That is, current-voltage characteristics of a photoelectric conversion element are measured at room temperature using an IV tester, and a short circuit current (I _sc ), an open circuit voltage (V _oc ), and a form factor (FF) are obtained. From these, the photoelectric conversion efficiency (η (%)) was determined. Furthermore, a bending test was performed 100 times in an environment of 60 ° C., and the photoelectric conversion efficiency before and after the comparison was compared.

  The evaluation results are shown in Table 2.

  From Table 2, the photoelectric conversion elements 1 and 2 of the present invention have a higher photoelectric conversion efficiency ratio (B / A) before and after bending than the comparative photoelectric conversion element 11, and the initial stage compared with the comparative photoelectric conversion element 12. It can be seen that the photoelectric conversion efficiency (A) is excellent. From this, it can be seen that by dispersing the semiconductor particles adsorbed with the dye in the p-type semiconductor polymer compound and further containing the n-type semiconductor compound, a photoelectric conversion element having higher durability and efficiency than the conventional one can be obtained. In particular, it can be seen that the photoelectric conversion element 1 in which an n-type semiconductor compound is adsorbed on a semiconductor particle together with a dye and then dispersed in a p-type semiconductor polymer compound has excellent performance.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Transparent conductive film 3 Insulating layer 4 Dye 5 Oxide semiconductor particle 6 N-type semiconductor compound 7 P-type semiconductor polymer compound 8 Semiconductor layer 9 Charge transport layer 10 Counter electrode

Claims (3)

  In the photoelectric conversion element having a semiconductor layer, a charge transport layer, and a counter electrode on a conductive support, the semiconductor layer has oxide semiconductor particles adsorbed with a dye dispersed in a p-type semiconductor polymer compound, And the said semiconductor layer contains an n-type semiconductor compound, The photoelectric conversion element characterized by the above-mentioned.   The photoelectric conversion element according to claim 1, wherein the n-type semiconductor compound is adsorbed to the oxide semiconductor particles together with a dye.   A solar cell comprising the photoelectric conversion element according to claim 1.

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