JP2007012545A - Dye-sensitized photoelectric conversion element, its manufacturing method, photoelectric conversion element module, electronic apparatus, movable body, and power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion element such as a dye-sensitized solar cell, capable of substantially reducing fluctuation of an amount of power generation with respect to an incident angle of light, and excellent in durability. <P>SOLUTION: A transparent conductive layer 2 and a dye-sensitized porous semiconductor layer 3 are provided one by one on the inner surface of a tube 1 made of a transparent material, a counter electrode 5 is inserted in the center part of the tube 1, the space between both end parts of the tube 1 and the counter electrode 5 is sealed by a sealing member, and an electrolyte layer 4 is sealed in the space between the dye-sensitized porous semiconductor layer 3 and the counter electrode 5 to form this dye-sensitized photoelectric conversion element. A quartz tube is used for the tube 1. The counter electrode 5 is formed in a rod shape, a cylindrical shape, or a wire shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dye-sensitized photoelectric conversion element, a method for producing a dye-sensitized photoelectric conversion element, a photoelectric conversion element module, an electronic device, a moving body, and a power generation system, for example, a dye-sensitized porous film composed of semiconductor fine particles carrying a dye. The present invention is suitable for application to dye-sensitized solar cells using a crystalline semiconductor layer and various devices, apparatuses, systems, etc. using the dye-sensitized solar cells.

When fossil fuels such as coal and oil are used as an energy source, it is said that the resulting carbon dioxide causes global warming. In addition, when using nuclear energy, there is a risk of contamination by radiation. Relying on these energies is very problematic now that environmental issues are being addressed.
On the other hand, solar cells, which are photoelectric conversion elements that convert sunlight into electrical energy, use sunlight as an energy source, and therefore have very little influence on the global environment, and are expected to become more widespread.

There are various types of materials for solar cells, but there are many commercially available materials using silicon. These are roughly divided into crystalline silicon solar cells using single crystal or polycrystalline silicon, and amorphous ( Amorphous) and silicon-based solar cells. Conventionally, monocrystalline or polycrystalline silicon, that is, crystalline silicon, has been used in many solar cells.
However, although the crystalline silicon solar cell has higher photoelectric conversion efficiency representing the ability to convert light (solar) energy into electric energy than the amorphous silicon solar cell, it requires much energy and time for crystal growth. Therefore, the productivity is low and the cost is disadvantageous.

  Amorphous silicon-based solar cells are more light-absorbing than crystalline silicon-based solar cells, have a wide substrate selection range, and are easy to increase in area, but have a photoelectric conversion efficiency of crystalline silicon. Lower than solar cells. Furthermore, although the productivity of amorphous silicon solar cells is higher than that of crystalline silicon solar cells, a vacuum process is required for production, and the burden on facilities is still large.

On the other hand, many solar cells using organic materials instead of silicon-based materials have been studied for further cost reduction of solar cells. However, the photoelectric conversion efficiency of this solar cell was as low as 1% or less, and there was a problem with durability.
In these circumstances, an inexpensive solar cell using semiconductor fine particles sensitized with a dye has been reported (for example, see Non-Patent Document 1). This solar cell is a wet solar cell using a titanium oxide porous thin film spectrally sensitized using a ruthenium complex as a sensitizing dye as a photoelectrode, that is, an electrochemical photocell. The advantages of this dye-sensitized solar cell are that inexpensive titanium oxide can be used, the light absorption of the sensitizing dye covers a wide visible light wavelength range up to 800 nm, the quantum efficiency of photoelectric conversion is high, and high energy conversion It is possible to achieve efficiency. Moreover, since a vacuum process is not necessary for production, a large-scale facility is not necessary.

A method for producing a TiO ₂ paste in which titanium oxide (TiO ₂ ) fine particles are dispersed is known (see, for example, Non-Patent Document 2).
Nature, 353, p.737-740,1991 Hironori Arakawa “Latest Technology for Dye-Sensitized Solar Cells” (CMC) p.45-47 (2001)

However, in solar cells, the energy source is sunlight, and the amount of power generated is not always constant because the amount of light and the incident angle change depending on the time, season, and weather. In fact, it is known that silicon solar cells have a proportional relationship between the amount of incident light and the amount of power generation, and the amount of power generation changes greatly with changes in the amount of light.
This problem is also present in the dye-sensitized solar cell to some extent, and a solution to this problem is desired.

  Accordingly, the problem to be solved by the present invention is that the optimization of the structure can greatly reduce the change in the amount of power generation with respect to the incident angle of light, and the dye sensitization of a dye-sensitized solar cell having high durability can be achieved. A photoelectric conversion element, a method for producing the same, and a photoelectric conversion element module, an electronic device, a moving body, and a power generation system using the dye-sensitized photoelectric conversion element are provided.

In order to solve the above problem, the first invention is:
A dye-sensitized photoconductor having a structure in which a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the center of the tube. It is a conversion element.

  The cross-sectional shape of the tube made of a transparent material is not limited, and may be a circle, an ellipse, a polygon (triangle, quadrangle, pentagon, hexagon, etc.), a part of or all of these shapes, and a longitudinal direction. A part or all of the cross-sectional shape may be changed. The tube may be straight or curved, and a straight portion and a curved portion may be mixed. Further, the length, outer diameter, and inner diameter of the tube can be determined as needed.

  The type of the transparent material is not particularly limited, and various materials can be used as long as they are transparent. The transparent material is preferably excellent in moisture and gas barrier properties, solvent resistance, weather resistance, and the like entering from the outside of the photoelectric conversion element. Specifically, the transparent material is a transparent inorganic substrate such as quartz or glass, polyethylene terephthalate. Transparent, such as polyethylene naphthalate, polycarbonate, polystyrene, polyethylene, polypropylene, polyphenylene sulfide, polyvinylidene fluoride, tetraacetylcellulose, brominated phenoxy, aramids, polyimides, polystyrenes, polyarylates, polysulfones, polyolefins Among them, it is preferable to use a plastic having a high transmittance in the visible light region, but it is not limited thereto. As this transparent material, it is preferable to use a transparent plastic in consideration of processability, lightness and the like. Further, the thickness of the transparent material (corresponding to the thickness of the tube) is not particularly limited, and can be freely selected depending on the light transmittance, the shielding property between the inside and the outside of the photoelectric conversion element, and the like.

A known material can be used for the transparent conductive layer. Specifically, indium (In) -tin (Sn) composite oxide (ITO), SnO ₂ (fluorine (F), antimony (Sb ), Indium (In) -zinc (Zn) composite oxide (IZO), ZnO, and the like, but are not limited to these, and two or more of these are included. It can also be used in combination.

By the way, in a dye-sensitized photoelectric conversion element such as a dye-sensitized solar cell, usually, a dye-sensitized porous semiconductor layer made of an n-type semiconductor is soaked with an electrolyte that is a liquid hole transfer layer. Therefore, there is a portion where the electrolyte is in direct contact with the transparent conductive layer, and leakage current due to a reverse electron transfer reaction from the transparent conductive layer to the electrolyte becomes a problem. Since this leakage current lowers the fill factor and open circuit voltage of the dye-sensitized photoelectric conversion element, it becomes a big problem in improving the photoelectric conversion efficiency. Therefore, it is important to significantly reduce the leakage current due to the reverse electron transfer reaction from the transparent conductive layer to the electrolyte. For this purpose, it is effective to sequentially provide a transparent conductive layer and a transparent protective layer made of a metal oxide on the inner surface of the tube and provide a dye-sensitized porous semiconductor layer on the inner surface of the protective layer. . By doing so, the transparent conductive layer is covered with a protective layer made of a metal oxide and is cut off from the electrolyte, and since the transparent conductive layer is not in direct contact with the electrolyte, the leakage current can be greatly reduced. It becomes. A dye-sensitized photoelectric conversion element having such a structure has a high fill factor and an open circuit voltage, and it is possible to realize a dye-sensitized photoelectric conversion element excellent in photoelectric conversion efficiency. The metal oxide constituting this protective layer is specifically selected from the group consisting of Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiSrO ₃ and SiO _2, for example. At least one metal oxide. The thickness of the protective layer is not particularly limited, but if it is too thin, the barrier between the transparent conductive layer and the electrolyte is poor, and conversely, if it is too thick, the transmittance is reduced and electron injection into the transparent conductive layer is lost. As a result, there will be a preferred thickness. This thickness is usually from 0.1 to 500 nm, particularly preferably from 1 to 100 nm.

The method for forming the transparent conductive layer on the inner surface of the tube made of a transparent material is not particularly limited, and various coating methods can be used, but a method of wet coating a precursor of a transparent conductive material and thermally decomposing it is preferable. As this wet coating method, various methods such as a spray coating method, a dip coating method, and a spin coating method can be used. Moreover, after the coating of the precursor of the transparent conductive material, it is preferable to perform heating for the purpose of decomposition of impurities and crystal growth for enhancing conductivity. Application and heating may be performed simultaneously, and for this purpose, it is particularly preferable to use a spray pyrolysis method because it is simple. This spray pyrolysis method is extremely advantageous in that the thickness of a layer that can be formed by one coating is several tens of times larger than that of a dip coating method or a spin coating method. Specifically, the thickness of the layer that can be formed by one coating by the spray pyrolysis method is, for example, about several hundred nm, and can be 500 nm or more.
In order to form a transparent conductive layer on the inner surface of a tube made of a transparent material, the transparent conductive layer is formed by doping the inner surface of the tube with an impurity capable of imparting conductivity to the transparent material to be used. It may be.

The dye-sensitized porous semiconductor layer (dye-sensitized semiconductor electrode) is typically composed of semiconductor fine particles carrying a dye. As a material for the semiconductor fine particles, various compound semiconductors, compounds having a perovskite structure, and the like can be used in addition to elemental semiconductors represented by silicon. These semiconductors are preferably n-type semiconductors in which conduction band electrons become carriers under photoexcitation and give an anode current. Specifically, these semiconductors are TiO ₂ , ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ , SnO _2, etc. Among these, anatase type TiO ₂ is particularly preferable. The types of semiconductor are not limited to these, and two or more of these can be used in combination. Furthermore, the semiconductor fine particles can take various forms such as particles, tubes, and rods as required.

  Although there is no restriction | limiting in particular in the particle size of semiconductor fine particle, 1-200 nm is preferable at the average particle diameter of a primary particle, Most preferably, it is 5-100 nm. It is also possible to improve the quantum yield by mixing semiconductor fine particles having an average particle size larger than the average particle size into semiconductor fine particles having an average particle size and scattering incident light by the semiconductor fine particles having a large average particle size. is there. In this case, the average particle diameter of the semiconductor fine particles to be mixed separately is preferably 20 to 500 nm.

  The porous semiconductor layer made of fine semiconductor particles preferably has a large surface area so that a large amount of dye can be adsorbed. For this reason, it is preferable that the surface area in the state which formed this porous semiconductor layer on the support body is 10 times or more with respect to a projection area, and it is more preferable that it is 100 times or more. The upper limit is not particularly limited, but is usually about 1000 times. In general, as the thickness of a porous semiconductor layer increases, the amount of supported dye increases per unit projected area and the light capture rate increases. However, the diffusion distance of injected electrons increases and the loss due to charge recombination increases. Become. Therefore, although there exists a preferable thickness in the porous semiconductor layer, the thickness is generally 0.1 to 100 μm, more preferably 1 to 50 μm, and particularly preferably 3 to 30 μm. preferable. The porous semiconductor layer made of semiconductor fine particles is preferably baked in order to make the semiconductor fine particles electronically contact each other after being formed on the support and to improve the film strength and the adhesion to the support. Although there is no restriction | limiting in particular in the range of a calcination temperature, Since resistance of a support body will become high and it may fuse | melt if it raises temperature too much, Usually, it is 40-700 degreeC, More preferably, it is 40-650 degreeC. is there. The firing time is not particularly limited, but is usually about 10 minutes to 10 hours. For example, a titanium tetrachloride aqueous solution or a titanium oxide ultrafine particle sol having a diameter of 10 nm or less may be subjected to dip treatment for the purpose of increasing the surface area of the porous semiconductor layer or increasing necking between the semiconductor fine particles after firing. It is also possible to apply a paste containing a binder on the transparent conductive layer and to press the transparent conductive layer with a hot press.

There is no particular limitation on the method for producing a porous semiconductor layer comprising semiconductor fine particles, but in view of physical properties, convenience, production costs, etc., a wet film-forming method is preferred, and the semiconductor fine particle powder or sol is dissolved in a solvent such as water. A method of preparing a uniformly dispersed paste and applying it on a transparent conductive layer provided on the inner surface of the tube is preferred. Coating is not particularly limited in its method and can be performed according to a known method, for example, dipping method, spray method, wire bar method, spin coating method, roller coating method, blade coating method, gravure coating method, As the wet printing method, for example, various methods such as letterpress, offset, gravure, intaglio, rubber plate, and screen printing can be used. When crystalline titanium oxide (TiO ₂ ) is used as the material for the semiconductor fine particles, the crystal type is preferably anatase type from the viewpoint of photocatalytic activity. The anatase type titanium oxide may be a commercially available powder, sol, or slurry, or may be made with a predetermined particle diameter by a known method such as hydrolysis of titanium oxide alkoxide. When using a commercially available powder, it is preferable to eliminate secondary aggregation of the particles, and it is preferable to pulverize the particles using a mortar, ball mill or the like when preparing the coating solution. At this time, acetylacetone, hydrochloric acid, nitric acid, a surfactant, a chelating agent, or the like can be added in order to prevent the particles after the secondary aggregation from being aggregated again. For the purpose of thickening, various thickeners such as polymers such as polyethylene oxide and polyvinyl alcohol, and cellulose-based thickeners can be added.

  The dye supported on the porous semiconductor layer is not particularly limited as long as it exhibits a sensitizing action. Specifically, for example, xanthene dyes such as rhodamine B, rose bengal, eosin, erythrosine, merocyanine, Examples include cyanine dyes such as quinocyanine and cryptocyanine, basic dyes such as phenosafranine, fog blue, thiocin, and methylene blue, and porphyrin compounds such as chlorophyll, zinc porphyrin, and magnesium porphyrin. Others include azo dyes and phthalocyanines. Examples thereof include compounds, coumarin compounds, ruthenium (Ru) bipyridine complex compounds, anthraquinone dyes, and polycyclic quinone dyes. Among these, a sensitizing dye of a complex of at least one metal selected from the group consisting of Ru, Os, Ir, Pt, Co, Fe and Cu, wherein the ligand (ligand) includes a pyridine ring or an imidazolium ring Is preferable because of its high quantum yield. In particular, cis-bis (isothiocyanato) -N, N-bis (2,2′-dipyridyl-4,4′-dicarboxylic acid) -ruthenium (II) or tris (isothiocyanato) -ruthenium (II) — A sensitizing dye molecule having 2,2 ': 6', 2 "-terpyridine-4,4 ', 4" -tricarboxylic acid as a basic skeleton has a wide absorption wavelength range and is preferable. However, the dyes are not limited to these, and two or more of these dyes may be mixed and used.

By the way, as a dye of a dye-sensitized solar cell, a dye molecule having a carboxylic acid as an adsorption group is generally used. Carboxylic acids are easily adsorbed on the oxide surface, and the dye can be supported without any special treatment, for example, by immersing the porous semiconductor layer in the dye solution. However, in dye-sensitized solar cells that use dye molecules with adsorbing groups of carboxylic acids as sensitizing dyes as described above, carboxylic acids are likely to form aggregates, so that the dyes cause association on the semiconductor surface. However, the electron trap between these dyes hinders the injection of electrons into the semiconductor and has a disadvantage that a reduction in photoelectric conversion efficiency is unavoidable. Therefore, a method for solving this drawback and enabling high photoelectric conversion efficiency to be obtained even when a dye having an acid functional group such as a carboxylic acid that easily forms an aggregate is used as an sensitizing dye. Study was carried out. As an example, let us consider a case where a molecule of a sensitizing dye has a plurality of carboxy groups (—COOH) as acid functional groups. As shown in FIG. 12A, the association occurs when the carboxy groups of the molecules of the dye form hydrogen bonds (shown by dotted lines). In order to prevent this association, it was considered to neutralize the acid functional group of the molecule of the sensitizing dye with an alkali compound such as NaOH. This neutralization, COOH sensitizing dye molecules COO ^- and became things by bonding Na ⁺ COO ^- has a state ^- but the Na ^+, in solution COO because of the dissociation. Since the neutralized and dissociated COO ⁻ is an anion, the sensitizing dye molecules are less likely to associate with each other due to repulsive force (charge repulsion) acting between the negative charges of the anion (FIG. 12B). Therefore, for example, when the porous semiconductor layer is immersed in this dye solution to support the dye, the dye molecules are less likely to associate on the semiconductor surface, and electron traps between these dyes can be greatly reduced. The above can basically be established also in the case of other acid functional groups such as phosphate groups and other alkaline compounds such as KOH. That is, in order to eliminate the above disadvantages, a dye molecule having a plurality of acid functional groups for adsorbing to the porous semiconductor layer is used, and a part of these acid functional groups is Li, Na, Neutralize with an alkali compound comprising at least one metal selected from the group consisting of K, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, imidazolium compounds and pyridinium compounds or a hydroxide of a compound. To do. Among these metals or compounds, Na, K, tetramethylammonium, tetraethylammonium, tetrapropylammonium, and 1-ethyl-3-methylimidazolium compounds are preferable, and among these, Na and K which are inorganic alkalis (alkali metals) are preferable. Particularly preferred. These inorganic alkalis have the effect of improving the conductivity of the porous semiconductor layer made of titanium oxide or the like, and since the ionic radius is small, the adsorption density of the dye to the porous semiconductor layer can be increased. . There is no particular limitation on the method of neutralizing the dye molecule, but for example, it can be carried out by mixing in a specified amount based on the number of moles of the dye and the alkali compound, or titration with pH. The partial neutralization of the dye may be performed before preparing the dye solution, or may be neutralized by mixing a predetermined amount of alkali in the dye solution. When neutralization of the dye molecules is performed in the dye solution, water is generated by the neutralization, and therefore, a water removal operation may be performed separately. The dye molecule has a plurality of acid functional groups, and some of them will be neutralized, but if the amount of partial neutralization of the dye molecule is too small, the association inhibition between the dye molecules is insufficient. On the other hand, if the amount is too large, sufficient photoelectric conversion cannot be performed due to a decrease in the adsorptive power of the dye molecules, so that an appropriate neutralization amount exists. The specific neutralization amount is preferably from 0.25 to 0.75, particularly preferably from 0.35 to 0.65, based on the number of acid functional groups in the dye molecule. This neutralization amount can be rephrased as a ratio to the total number of acid functional groups of the entire dye molecule.

  Although there is no particular limitation on the method of supporting (adsorbing) the dye on the porous semiconductor layer, the above dye can be used, for example, alcohols, nitriles, nitromethane, halogenated hydrocarbons, ethers, dimethyl sulfoxide, amides, N-methyl. Dissolve in a solvent such as pyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters, carbonates, ketones, hydrocarbons, water, etc. Can be applied onto the porous semiconductor layer. Further, deoxycholic acid or the like may be added for the purpose of reducing association between the dye molecules. Furthermore, you may use a ultraviolet absorber together.

  After the dye is adsorbed on the porous semiconductor layer, the surface of the porous semiconductor layer may be treated with amines for the purpose of promoting the removal of the excessively adsorbed dye. Examples of amines include pyridine, 4-tert-butylpyridine, polyvinylpyridine, and the like. When these are liquid, they may be used as they are, or may be used after being dissolved in an organic solvent.

  By the way, in a dye-sensitized photoelectric conversion element such as a dye-sensitized solar cell, an additive composed of a substance that binds to the dye-sensitized porous semiconductor layer is usually added in order to prevent reverse electron transfer in the electrolytic solution. As this additive, tert-butylpyridine, 1-methoxybenzimidazole, phosphonic acid having a long-chain alkyl group (about C = 13) or the like is used. The characteristics of these additives are that they can be mixed uniformly in the electrolyte and have functional groups that can be bonded to the dye-sensitized porous semiconductor layer. However, according to the knowledge of the present inventor, in the conventional dye-sensitized solar cell, the dye previously adsorbed on the surface of the porous semiconductor layer after the electrolytic solution is sealed is eluted, and the photoelectric conversion efficiency is rapidly increased. It was confirmed that it deteriorated. Therefore, it is necessary to prevent the elution of the dye previously adsorbed to the porous semiconductor layer while preventing the reverse electron transfer reaction, thereby improving the photoelectric conversion efficiency. For this purpose, instead of adding an additive to the electrolytic solution, a dye and an additive are adsorbed in advance on the porous semiconductor layer, and at this time, the additive is adsorbed in a gap portion between the dyes and is added to the electrolytic solution. It is effective not to contain any additives. As the method, for example, the porous semiconductor layer adsorbed with the dye is immersed in a solution containing the additive to adsorb the additive on the surface of the porous semiconductor layer in the gap between the dye, An electrolyte containing no additive is sealed between the porous semiconductor layer on which the dye and additive are adsorbed and the counter electrode. By doing so, the additive adsorbed on the dye-sensitized porous semiconductor layer can prevent the reverse electron transfer reaction and prevent the elution of the dye by the electrolyte, effectively reducing the deterioration of photoelectric conversion efficiency over time. Can be prevented. As an additive, it has a functional group (imidazolyl group, carboxy group, phosphone group, etc.) that binds to the porous semiconductor layer, does not cause desorption as a result of bonding, and is exposed to the surface of the porous semiconductor layer as a result of adsorption. Specifically, for example, phosphonic acid having a long-chain alkyl group (about C = 13) such as tert-butylpyridine, 1-methoxybenzimidazole, and decanephosphoric acid is used. .

  Any material can be used as the counter electrode as long as it is a conductive substance, but even an insulating substance can be used if a conductive layer is provided on the side facing the dye-sensitized porous semiconductor layer. Is possible. However, as the counter electrode material, an electrochemically stable material is preferably used, and specifically, platinum, gold, carbon, a conductive polymer, or the like is preferably used. For the purpose of improving the catalytic effect of redox, it is preferable that the side facing the dye-sensitized porous semiconductor layer has a fine structure and an increased surface area. If it is carbon, it is desirable that it is in a porous state. The platinum black state can be formed by anodization of platinum, chloroplatinic acid treatment, and the like, and the porous carbon can be formed by a method such as sintering of carbon fine particles or firing of an organic polymer. Moreover, it can also be used as a transparent counter electrode by wiring a metal having a high redox catalyst effect such as platinum on the transparent conductive substrate or treating the surface with chloroplatinic acid. There is no restriction | limiting in the shape of this counter electrode, Any of rod shape, tubular shape, wire shape, etc. may be sufficient, but it is preferable that it is a shape along the inner surface of a transparent base material.

Electrolytes include combinations of iodine (I ₂ ) and metal iodide or organic iodide, bromine (Br ₂ ) and metal bromide or organic bromide, ferrocyanate / ferricyanate, ferrocene / ferri Metal complexes such as sinium ion, sodium polysulfide, sulfur compounds such as alkyl thiol / alkyl disulfide, viologen dye, hydroquinone / quinone, and the like can be used. Lithium, Na, K, Mg, Ca, Cs and the like are preferable as the cation of the metal compound, and quaternary ammonium compounds such as tetraalkylammonium, pyridinium, and imidazolium are preferable as the cation of the organic compound. It is not limited, and two or more of these can be mixed and used. Among these, an electrolyte obtained by combining I ₂ and a quaternary ammonium compound such as LiI, NaI or imidazolium iodide is preferable. The concentration of the electrolyte salt is preferably 0.05 to 10M, more preferably 0.2 to 3M with respect to the solvent. The concentration of I ₂ or Br ₂ is preferably 0.0005 to 1M, more preferably 0.001 to 0.1M. Various additives such as 4-tert-butylpyridine and carboxylic acid can be added for the purpose of improving the open circuit voltage and the short circuit current.

  Water, alcohols, ethers, esters, carbonate esters, lactones, carboxylic acid esters, phosphoric acid triesters, heterocyclic compounds, nitriles, ketones, amides as a solvent constituting the electrolyte composition Nitromethane, halogenated hydrocarbons, dimethyl sulfoxide, sulfolane, N-methylpyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, hydrocarbons and the like, but are not limited thereto, Moreover, these can also be used in mixture of 2 or more types. Furthermore, it is also possible to use a room temperature ionic liquid of a tetraalkyl, pyridinium, or imidazolium quaternary ammonium salt as a solvent.

  For the purpose of reducing leakage of the photoelectric conversion element and volatilization of the electrolyte, it is possible to dissolve the gelling agent, polymer, cross-linking monomer, etc. in the above electrolyte composition and use it as a gel electrolyte. The ratio of the gel matrix to the electrolyte composition is such that the more the electrolyte composition, the higher the ionic conductivity, but the mechanical strength decreases. Conversely, if the electrolyte composition is too small, the mechanical strength increases but the ionic conductivity. Therefore, the electrolyte composition is desirably 50 to 99 wt%, more preferably 80 to 97 wt% of the gel electrolyte. It is also possible to realize an all-solid photoelectric conversion element by dissolving the electrolyte and the plasticizer in a polymer and volatilizing and removing the plasticizer.

  The method for producing the photoelectric conversion element is not particularly limited. For example, the electrolyte composition can be liquid or gelled inside the photoelectric conversion element, and in the case of a liquid electrolyte composition, a dye is supported before introduction. The dye-sensitized porous semiconductor layer is not formed so that a counter electrode such as a rod, tube or wire is inserted into the tubular dye-sensitized porous semiconductor layer so that these two electrodes do not contact each other. Seal using part. At this time, although there is no restriction | limiting in particular in the magnitude | size of the clearance gap between a dye-sensitized porous semiconductor layer and a counter electrode, Usually, it is 1-100 micrometers, More preferably, it is 1-50 micrometers. If the distance between these electrodes is too long, the photocurrent decreases due to the decrease in conductivity. The sealing method is not particularly limited, but it is preferable to use a material having light resistance, insulation, and moisture resistance. Epoxy resin, ultraviolet curable resin, acrylic resin, EVA (ethylene vinyl acetate), ionomer resin, modified polyethylene ( Propylene), ceramics, various heat-sealing films, and the like, and various welding methods can be used. Moreover, although the injection port which injects the solution of electrolyte composition is required, if it is not on the counter electrode of the dye-sensitized porous semiconductor layer and the part facing it, the location of an injection port will not be specifically limited. Although there is no restriction | limiting in particular in the liquid injection method, The method of injecting into the inside of the element sealed beforehand and opened the injection port of the solution is preferable. In this case, a method of dropping a few drops of the solution at the injection port and injecting the solution by capillary action is simple. In addition, the injection operation can be performed under reduced pressure or under heating as necessary. After the solution is completely injected, the solution remaining at the inlet is removed and the inlet is sealed. Although there is no restriction | limiting in particular also in this sealing method, If necessary, it can also seal by affixing a glass plate or a plastic substrate with a sealing agent. In the case of a gel electrolyte using a polymer or the like, or an all solid electrolyte, a polymer solution containing an electrolyte composition and a plasticizer is volatilized and removed by a casting method on a porous semiconductor layer on which a dye is adsorbed. After completely removing the plasticizer, sealing is performed in the same manner as in the above method. This sealing is preferably performed using a vacuum sealer or the like under an inert gas atmosphere or under reduced pressure. After sealing, in order to sufficiently immerse the electrolyte in the dye-sensitized porous semiconductor layer, it is possible to perform heating and pressurizing operations as necessary.

The dye-sensitized photoelectric conversion element can be produced in various shapes depending on the application, and the shape is not particularly limited.
The dye-sensitized photoelectric conversion element is most typically configured as a dye-sensitized solar cell. This dye-sensitized solar cell can be used for anything that requires about electric power and can be of any size. For example, it can be used for electronic equipment, moving objects, power units, construction machines, machine tools, power generation systems, etc. The output, size, shape, etc. are determined depending on the application. However, the dye-sensitized photoelectric conversion element may be other than a dye-sensitized solar cell, for example, a dye-sensitized photosensor.

The second invention is
A method for producing a dye-sensitized photoelectric conversion element having a structure in which a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the central portion of the tube Because
The transparent conductive layer is formed on the inner surface of the tube by a wet coating method.
In the second invention, what has been described in relation to the first invention is valid as long as it is not against the nature thereof.

The third invention is
In the photoelectric conversion element module in which a plurality of photoelectric conversion elements are arranged and wired,
At least one of the photoelectric conversion elements is
A dye-sensitized photoelectric conversion element having a structure in which a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the center of the tube. It is characterized by.

In this case, all of the plurality of photoelectric conversion elements may be the above dye-sensitized photoelectric conversion elements, or the above-described dye-sensitized photoelectric conversion elements and other photoelectric conversion elements, specifically, conventional general-purpose photoelectric conversion elements. A combination with a dye-sensitized photoelectric conversion element or a silicon-based photoelectric conversion element having a typical planar structure may be used. In order to significantly reduce the change in the amount of power generation with respect to the incident angle of light and to effectively use light in a wider wavelength band of the sunlight spectrum, it is preferable that at least light in different wavelength bands can be photoelectrically converted. Two types of the above dye-sensitized photoelectric conversion elements are included.
The form of this photoelectric conversion element module is not particularly limited, and can be determined as necessary. In addition, the arrangement method of the plurality of photoelectric conversion elements is not particularly limited and can be determined as necessary. Specifically, for example, two-dimensionally arranging them in parallel or stacking a plurality of stages to form a tertiary It can be arranged originally. In order to form a photoelectric conversion element module, specifically, for example, a plurality of these photoelectric conversion elements are arranged and sandwiched between two transparent substrates (such as a glass substrate), and these photoelectric conversions are performed. After wiring between the elements, silicone resin or the like is filled in the gaps between the elements and cured. The wiring method between the plurality of photoelectric conversion elements may be either serial or parallel.
In the third aspect of the invention, what has been described in relation to the first aspect of the invention other than the above is valid as long as it is not contrary to the nature thereof.

The fourth invention is:
In electronic equipment using dye-sensitized photoelectric conversion elements,
The dye-sensitized photoelectric conversion element is
A transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted into the central portion of the tube.
This electronic device may basically be any type, and includes both portable and stationary types. Specific examples include cell phones, mobile devices, robots, personal computers, and the like. Computers, game devices, in-vehicle devices, home appliances, industrial products, etc.
In the fourth invention, the matters other than the above are explained in relation to the first invention unless they are contrary to the nature.

The fifth invention is:
In a moving body using a dye-sensitized photoelectric conversion element,
The dye-sensitized photoelectric conversion element is
A transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted into the central portion of the tube.
This moving body may be basically any type, and specific examples include automobiles, two-wheeled vehicles, aircraft, rockets, and space ships.
In the fifth invention, what has been described in relation to the first invention holds true for matters other than those described above, unless they are contrary to the nature thereof.

The sixth invention is:
In a power generation system using a dye-sensitized photoelectric conversion element,
The dye-sensitized photoelectric conversion element is
A transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted into the central portion of the tube.
This power generation system may be basically any type, and its scale is not limited.
In the sixth aspect of the invention, what has been described in relation to the first aspect of the invention other than the above is valid as long as it is not contrary to the nature thereof.

In the present invention configured as described above, the dye-sensitized photoelectric conversion element has a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer sequentially provided on the inner surface of a tube made of a transparent material. By having a structure in which a counter electrode is inserted in the center, the dye-sensitized porous semiconductor layer itself has a structure in which light can be easily confined in a very small void inside, and from which direction the light enters the tube. Since light can also be photoelectrically converted, changes in the amount of power generation with respect to the incident angle of light can be greatly reduced.
Further, in this dye-sensitized photoelectric conversion element, in order to prevent the electrolyte from leaking to the outside, for example, a counter electrode is inserted into the tube, and a sealing member is used between the both ends of the tube and the counter electrode. Sealing is sufficient. Therefore, like a conventional planar structure dye-sensitized photoelectric conversion element, a transparent conductive substrate on which a dye-sensitized porous semiconductor layer is formed and a substrate on which a counter electrode is formed are opposed to each other, and the outer peripheral portion thereof is a sealing member. Compared with the case of sealing by, it is possible to significantly reduce the area of the sealing portion. Thereby, the durability of the dye-sensitized photoelectric conversion element, particularly the durability in the outdoors can be significantly improved.

  According to the present invention, by optimizing the structure of the dye-sensitized photoelectric conversion element, a change in the amount of power generation with respect to the incident angle of light can be greatly reduced, and durability can be improved. By using such an excellent dye-sensitized photoelectric conversion element, it is possible to obtain a high-performance photoelectric conversion element module, an electronic device, a moving body, and a power generation system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts are denoted by the same reference numerals.
1 to 3 show a dye-sensitized photoelectric conversion element according to a first embodiment of the present invention, FIG. 1 is a side view, FIG. 2 is a longitudinal sectional view, and FIG. 3 is a transverse sectional view.
As shown in FIG. 1 to FIG. 3, this dye-sensitized photoelectric conversion element has a dye-sensitized porous layer made of semiconductor fine particles carrying a transparent conductive layer 2 and a dye on the inner surface of a circular cross-section tube 1 made of a transparent material. A semiconductor layer 3 (dye-sensitized semiconductor electrode) and an electrolyte layer 4 are sequentially provided, and a counter electrode 5 is inserted into the central portion of the tube 1 so as to extend along the central axis of the tube 1. The counter electrode 5 has, for example, a rod shape, a tubular shape, or a wire shape. In this case, the counter electrode 5 is slightly longer than the tube 1, one end portion 5 a thereof substantially coincides with the one end portion 1 a of the tube 1, and the other end portion 5 b projects slightly from the other end portion 1 b of the tube 1. Between the one end 1a of the tube 1 and one end 5a of the counter electrode 5 and between the other end 1b of the tube 1 and the other end 5b of the counter electrode 5 are sealed by a sealing member 6, and the electrolyte layer 4 Is not leaked to the outside. Lead wires 7 and 8 are connected to the counter electrode 5 and the transparent conductive layer 2, respectively.
The transparent material, the transparent conductive layer 2, the dye-sensitized porous semiconductor layer 3, the electrolyte layer 4 and the counter electrode 5 constituting the tube 1 can be selected from those already mentioned as necessary.
Moreover, there is no restriction | limiting in particular in the length and diameter of this dye-sensitized photoelectric conversion element, and it determines suitably according to the use, output, etc. of this dye-sensitized photoelectric conversion element.

Next, the manufacturing method of this dye-sensitized photoelectric conversion element is demonstrated.
First, a tube 1 made of a transparent material and having a predetermined length, outer diameter, and inner diameter is prepared. Next, the transparent conductive layer 2 is formed on the inner surface of the tube 1. For the formation of the transparent conductive layer 2, for example, a wet coating method, preferably a spray pyrolysis method is used. Next, a paste in which semiconductor fine particles are dispersed is applied to the inner surface of the transparent conductive layer 2 to a predetermined thickness. Next, the entire tube 1 and the transparent conductive layer 2 are heated to a predetermined temperature to sinter the semiconductor fine particles. Next, the semiconductor fine particles are supported on the dye by, for example, immersing the entire tube 1 and the transparent conductive layer 2 in which the semiconductor fine particles are sintered in a dye solution. Thus, the dye-sensitized porous semiconductor layer 3 is formed.

  On the other hand, a counter electrode 5 having a predetermined length and diameter is prepared. Then, the counter electrode 5 is inserted into the central portion of the tube 1, and the counter electrode 5 and the tube 1 are separated from each other by a predetermined interval, for example, the counter electrode 5 and the dye-sensitized porous semiconductor layer 3 formed on the inner surface of the tube 1. 1 to 100 μm, preferably 1 to 50 μm, so as to be opposed to each other, and between the one end 1 a of the tube 1 and one end 5 a of the counter electrode 5 and between the other end 1 b of the tube 1 and the counter electrode 5. The other end portion 5b is sealed with a sealing member 6 to create a space in which the electrolyte layer 4 is enclosed, and the electrolyte layer 4 is injected into the space from an injection port formed in advance. Thereafter, the inlet is closed. Next, lead wires 7 and 8 are connected to the counter electrode 5 and the transparent conductive layer 2, respectively. In this way, a dye-sensitized photoelectric conversion element is manufactured.

Next, the operation of this dye-sensitized photoelectric conversion element will be described.
Light incident on the tube 1 from the outside passes through the tube 1 and the transparent conductive layer 2 and enters the dye-sensitized porous semiconductor layer 3, and excites the dye of the dye-sensitized porous semiconductor layer 3 to generate electrons. Is generated. The electrons are quickly transferred from the dye to the semiconductor fine particles of the dye-sensitized porous semiconductor layer 3. On the other hand, the dye that has lost the electrons receives electrons from the ions of the electrolyte layer 4, and the molecule that has passed the electrons receives electrons again at the surface of the counter electrode 5. By this series of reactions, an electromotive force is generated between the transparent conductive layer 2 electrically connected to the dye-sensitized porous semiconductor layer 3 and the counter electrode 5. In this way, photoelectric conversion is performed.

  As described above, according to the first embodiment, the dye-sensitized photoelectric conversion element has the transparent conductive layer 2, the dye-sensitized porous semiconductor layer 3, and the electrolyte layer 4 on the inner surface of the tube 1 made of a transparent material. By having a structure in which the counter electrode 5 is inserted in the central portion of the tube 1 in order, photoelectric conversion is possible regardless of the direction of light incident on the surface of the tube 1. It is possible to greatly reduce the change in the amount of power generation with respect to. In addition, since this dye-sensitized photoelectric conversion element has a very small sealing area, it has excellent durability outdoors.

Example 1
TiO ₂ fine particles were used as the semiconductor fine particles. A paste in which TiO ₂ fine particles were dispersed was prepared as follows with reference to Non-Patent Document 2. 125 ml of titanium isopropoxide was slowly added dropwise to 750 ml of 0.1 M nitric acid aqueous solution with stirring at room temperature. When the dropping was completed, this solution was transferred to a constant temperature bath at 80 ° C. and stirred for 8 hours to obtain a cloudy translucent sol solution. The sol solution was allowed to cool to room temperature, filtered through a glass filter, and then made up to 700 ml. The obtained sol solution was transferred to an autoclave, hydrothermally treated at 220 ° C. for 12 hours, and then subjected to dispersion treatment by performing ultrasonic treatment for 1 hour. Next, this solution was concentrated by an evaporator at 40 ° C. to prepare a TiO ₂ content of 20 wt%. To the concentrate sol solution was added anatase TiO ₂ of 30 wt% of the particle size 200nm TiO ₂ with in the paste and 20 wt% polyethylene glycol (molecular weight 500,000) with respect to TiO ₂ in the paste, these The mixture was uniformly mixed with a stirring deaerator to obtain a thickened TiO ₂ paste.

A quartz tube (inner diameter 2.5 mmφ, length 50 mm) is used as the tube 1 made of a transparent material, and transparent conductive material is formed on the inner wall of the quartz tube by spray pyrolysis using ammonium fluoride and ethanol solution of dibutyltin diacetate. As layer 2, a fluorine-doped SnO ₂ film was formed. In addition, two holes of 0.5 mmφ were formed in this quartz tube as injection ports for electrolyte injection.
Next, the outer peripheral surface of the quartz tube is masked with a mask material, and the TiO ₂ paste obtained as described above is dip-coated on the fluorine-doped SnO ₂ film as the transparent conductive layer 2 formed on the inner surface of the quartz tube. After coating by the method, it was kept at 450 ° C. for 30 minutes, and TiO ₂ was sintered on this fluorine-doped SnO ₂ film. Next, the quartz tube thus sintered in TiO ₂ is immersed in a 0.05 M TiCl ₄ aqueous solution, kept at 70 ° C. for 30 minutes, washed, and then fired again at 450 ° C. for 30 minutes. It was.
Next, for the purpose of removing impurities and increasing the activity of the TiO ₂ sintered body thus produced, ultraviolet exposure was performed for 30 minutes with an ultraviolet irradiation device.

Next, 0.3 mM cis-bis (isothiocyanate) -N, N-bis (2,2′-dipyridyl-4,4′-dicarboxylic acid) -ruthenium (II) ditetrabutylammonium salt (cis- A tert-butyl alcohol / acetonitrile mixed solvent in which bis (isothiocyanato) bis (2,2′-bipyridyl-4,4′-dicarboxylato) -ruthenium (II) bis-tetrabutylammonium salt) (N719 dye) is dissolved (volume ratio 1: In 1), the above TiO ₂ sintered body was immersed at room temperature for 24 hours to carry the dye. This TiO ₂ sintered body was washed sequentially with an acetonitrile solution of 4-tert-butylpyridine and acetonitrile and dried in the dark.

As the counter electrode 5, a Ti rod having a diameter of 2.4 mmφ and a length of 60 mm and subjected to Pt plating (thickness: 200 nm) was used.
Next, the Pt-plated Ti rod was inserted into the quartz tube prepared as described above, and the end of the quartz tube was sealed to the sealing member 6 using an acrylic UV curable resin.

Meanwhile, 3 g of methoxyacetonitrile, 0.04 g of sodium iodide (NaI), 0.479 g of 1-propyl-2,3-dimethylimidazolium iodide, 0.0381 g of iodine (I ₂ ), 4-tert-butylpyridine 2 g was dissolved to prepare an electrolyte composition.
The mixed solution was injected from an injection port previously formed in the quartz tube using a liquid feed pump, and the bubbles inside the device were driven out by reducing the pressure. Next, an acrylic UV curable resin was dropped into the injection port, and the glass substrate was covered and cured to obtain a dye-sensitized photoelectric conversion element.
The effective area of the dye-sensitized photoelectric conversion element is 1 cm ² (0.25 cm (inner diameter of the quartz tube) × 4 cm (length of the TiO ₂ sintered body) with respect to the incident direction of light.

Example 2
As shown in FIGS. 4 and 5, a photoelectric conversion element module was prepared using the dye-sensitized photoelectric conversion element 10 prepared in Example 1. Here, FIG. 4 and FIG. 5 are a plan view and a cross-sectional view of the photoelectric conversion element module, respectively.
That is, as shown in FIG. 4 and FIG. 5, ten dye-sensitized photoelectric conversion elements 10 prepared in Example 1 are connected in series, and are sandwiched between two 50 mm square glass substrates 11 and 12, The two-component mixed silicone rubber 13 was filled in the gap and cured to obtain a photoelectric conversion element module 20. The effective area of the photoelectric conversion element module 20 is 10 cm ² (0.25 cm × 4 cm × 10 cells) with respect to the incident direction of light.

Comparative Example 1
Dye-sensitized photoelectric conversion as in Example 1 except that a 10 mm × 50 mm flat quartz substrate was used as the transparent substrate and a 10 mm × 50 mm flat Ti plate plated with Pt (thickness 200 nm) was used as the counter electrode. An element was produced. The effective area of the dye-sensitized photoelectric conversion element is 1 cm ² (0.25 cm × 4 cm) with respect to the incident direction of light.
Comparative Example 2
Ten dye-sensitized photoelectric conversion elements prepared in Comparative Example 1 were connected in series, sandwiched between two 50 mm square glass substrates, filled with a two-component mixed silicone rubber in the gap, cured, A photoelectric conversion element module was obtained. The effective area of the photoelectric conversion element module is 10 cm ² (0.25 cm × 4 cm × 10 cells) with respect to the incident direction of light.

In the dye-sensitized photoelectric conversion element of Example 1 and Comparative Example 1 manufactured as described above and the photoelectric conversion element module of Example 2 and Comparative Example 2, irradiation with pseudo sunlight (AM1.5, 100 mW / cm ² ) FIG. 6 shows the maintenance efficiency of photoelectric conversion efficiency when the incident angle of light is changed from 90 ° to 0 °.
The photoelectric conversion element and the photoelectric conversion element module were exposed to the outdoors, and the photoelectric conversion efficiency was measured up to 90 days every 10 days. FIG. 7 shows the maintenance rate of the photoelectric conversion efficiency at this time.

FIG. 6 shows that the photoelectric conversion efficiency of the dye-sensitized photoelectric conversion element of Example 1 has no dependency on the incident angle of light. In addition, the photoelectric conversion element module of Example 2 also has less dependency on the incident angle of light of photoelectric conversion efficiency than the photoelectric conversion element module of Comparative Example 2, and can perform photoelectric conversion at a wider angle.
Moreover, it can be seen from FIG. 7 that the dye-sensitized photoelectric conversion element of Example 1 and the photoelectric conversion element module of Example 2 have high photoelectric conversion efficiency maintenance rates in outdoor exposure.

Example 3
Black dye as a dye, that is, tris (isothiocyanate) -ruthenium (II) -2,2 ′: 6 ′, 2 ″ -terpyridine-4,4 ′, 4 ″ -tricarboxylic acid, tris-tetrabutylammonium salt Example except that (tris (isothiocyanato) -ruthenium (II) -2,2 ': 6', 2 ''-terpyridine-4,4 ', 4''-tricarboxylic acid, tris-tetrabutylammonium salt) was used As in Example 1, a dye-sensitized photoelectric conversion element was produced. The effective area of the dye-sensitized photoelectric conversion element is 1 cm ² (0.25 cm × 4 cm) with respect to the incident direction of light.

As shown in FIG. 8, 10 dye-sensitized photoelectric conversion elements 10 produced in Example 1 were connected in series and 10 dye-sensitized photoelectric conversion elements 30 produced in Example 3 were connected in series. Are stacked between two 50 mm square glass substrates 11 and 12, and the two-component mixed silicone rubber 13 is filled in the gap and cured, and the photoelectric conversion element module 40 is assembled. Obtained. The effective area of the photoelectric conversion element module 40 is 10 cm ² (0.25 cm × 4 cm × 10 cells) with respect to the incident direction of light.

  In this photoelectric conversion element module 40, N719 used as a dye in the dye-sensitized photoelectric conversion element 10 of Example 1 has an absorption peak near a wavelength of 500 nm. In the dye-sensitized photoelectric conversion element 30 of Example 3, Since the black dye used as the dye has an absorption peak near the wavelength of 650 nm and the wavelength bands of the absorption bands are different from each other, only the dye-sensitized photoelectric conversion element 10 or only the dye-sensitized photoelectric conversion element 30 is used. Compared with the photoelectric conversion element module, light in a wider wavelength band of the sunlight spectrum can be photoelectrically converted, and higher quantum efficiency can be obtained. For this reason, power generation amount can be increased.

Next explained is a dye-sensitized photoelectric conversion element according to the second embodiment of the invention.
In this dye-sensitized photoelectric conversion element, in the dye-sensitized porous semiconductor layer 3, the dye molecule is adsorbed to the semiconductor fine particles by its acid functional group, and a part of the acid functional group of the dye molecule is Li , Na, K, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, imidazolium compounds and neutralized with an alkali compound consisting of a hydroxide of a compound selected from the group consisting of pyridinium compounds Has become an anion. By doing so, association between the dye molecules is suppressed by the repulsive force acting between the anions, and an electron trap between the dye molecules can be greatly reduced. Others are the same as those of the dye-sensitized photoelectric conversion element according to the first embodiment.

  The method for producing the dye-sensitized photoelectric conversion element is as follows. In the dye solution, for example, a part of the acid functional group of the dye molecule is previously Li, Na, K, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium. The dye sensitization according to the first embodiment except that it is neutralized with an alkali compound comprising at least one metal selected from the group consisting of an imidazolium compound and a pyridinium compound or a hydroxide of a compound to form an anion. It is the same as the manufacturing method of a photoelectric conversion element.

  According to the second embodiment, in addition to the same advantages as those of the first embodiment, the following advantages can be obtained. That is, by neutralizing a part of the acid functional group of the dye with an alkali compound, the acid functional group becomes an anion, and the repulsive force (charge repulsion) acting between the negative charges makes it difficult for the sensitizing dye molecules to associate with each other. Therefore, the electron traps between the dye molecules can be significantly reduced, whereby the current and voltage of the dye-sensitized photoelectric conversion element can be greatly increased, and the photoelectric conversion efficiency can be improved.

Example 4
A dye-sensitized photoelectric conversion element was produced in the same manner as in Example 1 except that the following process was used when the dye was supported after removing impurities from the TiO ₂ sintered body and further subjected to ultraviolet exposure.
That is, fully purified cis-bis (isothiocyanate) -N, N-bis (2,2′-dipyridyl-4,4′-dicarboxylic acid) -ruthenium (II) dihydrate at a concentration of 1 mM. Dissolved in methanol. Next, 0.5 times the amount of carboxylic acid was added to this solution and stirred sufficiently to neutralize the carboxy group, and then concentrated with an evaporator and recrystallized with diethyl ether. The precipitate was separated by filtration, washed with diethyl ether, and dried by vacuum drying at 50 ° C. for 24 hours.

Next, the cis-bis (isothiocyanate) -N, N-bis (2,2 ′) thus obtained is obtained.
- dipyridyl-4,4 '- dicarboxylic acid) - ruthenium (II) the 2Na salt was dissolved at a concentration of 0.3 mM tert-butyl alcohol / acetonitrile mixed solvent (volume ratio 1: 1) of the above TiO ₂ sintered body Was immersed at room temperature for 24 hours to carry the dye. This TiO ₂ sintered body was washed sequentially with an acetonitrile solution of 4-tert-butylpyridine and acetonitrile and dried in the dark.
In the dye-sensitized photoelectric conversion element of Example 4 thus prepared, the fill factor and the open-circuit voltage are dramatically improved as compared with those using a dye without partial neutralization and a dye with complete neutralization, and photoelectric conversion Excellent efficiency.

Next explained is a dye-sensitized photoelectric conversion element according to the third embodiment of the invention.
As shown in FIG. 9, in this dye-sensitized photoelectric conversion element, a transparent metal oxide layer 9 is provided on the transparent conductive layer 2, and a dye-sensitized porous semiconductor layer 3 is provided thereon. . Specifically, for example, after forming the transparent conductive layer 2, an Nb ₂ O ₅ layer having a thickness of 20 nm is formed as the metal oxide layer 9 by a wet coating method, for example, a spray pyrolysis method. Others are the same as those of the dye-sensitized photoelectric conversion element according to the first embodiment.

  According to the third embodiment, in addition to the same advantages as those of the first embodiment, the following advantages can be obtained. That is, since the metal oxide layer 9 prevents the transparent conductive layer 2 and the electrolytic solution used as the electrolyte layer 4 from being in direct contact with each other, the leakage current due to the reverse electron transfer reaction can be greatly reduced, thereby The fill factor and the open circuit voltage can be increased, and the photoelectric conversion efficiency can be further improved.

Next explained is a dye-sensitized photoelectric conversion element according to the fourth embodiment of the invention.
As shown in FIG. 10, in this dye-sensitized photoelectric conversion element, not only the dye 51 is adsorbed to the dye-sensitized porous semiconductor layer 3, but also an additive in the gap portion between the dye 51. 52 is also adsorbed. In this case, no additive is added to the electrolytic solution constituting the electrolyte layer 4 unlike the conventional case. The pigment | dye 51 and the additive 52 can be selected as needed from what was already mentioned, for example. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

Next, the manufacturing method of this dye-sensitized photoelectric conversion element is demonstrated.
First, similarly to the first embodiment, the transparent conductive layer 2 and the dye-sensitized porous semiconductor layer 3 are sequentially formed on the inner surface of the tube 1. The dye-sensitized porous semiconductor layer 3 in this state is schematically shown in FIG. 11A. This dye-sensitized porous semiconductor layer 3 is formed in the same manner as in the first embodiment.
Next, as shown in FIG. 11B, a solution 54 in which an additive 52 is dissolved in a solvent is placed in a container 53, and the tube 1 in which the dye-sensitized porous semiconductor layer 3 is formed in the solution 54 is obtained. Immersion is performed, and the container 54 is further covered with a lid 55 to adsorb the additive 52 to the dye-sensitized porous semiconductor layer 3. Specific examples include NaI 0.1M, 1-propyl-2,3 dimethylimidazolium iodide (DMP II) 0.6M, I ₂ 0.05M, and tert-butylpyridine (TBP) as an additive. ) Prepare an electrolyte solution consisting of a 0.5M methoxyacetonitrile (MeACN) solution, immerse the dye-sensitized porous semiconductor layer 3 in this electrolyte solution for 5 to 10 minutes, and increase the dye concentration at the site where the dye could not be adsorbed. Tert-butylpyridine as an additive 52 was adsorbed on the surface of the porous semiconductor layer 3. Thereafter, the electrolytic solution adhering to the dye-sensitized porous semiconductor layer 3 is rinsed off with methoxyacetonitrile and air-dried.

After adsorbing the additive 52 in this way, the tube 1 on which the dye-sensitized porous semiconductor layer 3 is formed is taken out from the container 53. Thereafter, the surface of the dye-sensitized porous semiconductor layer 3 is washed. The dye-sensitized porous semiconductor layer 3 in this state is schematically shown in FIG. 11C.
Thereafter, similarly to the first embodiment, the counter electrode 5 is inserted into the central portion of the tube 1, and the electrolyte layer 4 is sealed between them, thereby producing the dye-sensitized photoelectric conversion element shown in FIG.

  According to the fourth embodiment, the following advantages can be obtained in addition to the advantages similar to those of the first embodiment. That is, since the additive 52 is adsorbed in advance on the dye-sensitized porous semiconductor layer 3 and the electrolyte solution to which the additive 52 is not added is used as the electrolyte layer 4, the dye-sensitized porous semiconductor layer 3 While the reverse electron transfer reaction is prevented by the additive 52 adsorbed on the surface in advance, the deterioration of photoelectric conversion efficiency with time can be prevented, and the lifetime can be improved.

Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and examples, and various modifications based on the technical idea of the present invention are possible. It is.
For example, the numerical values, structures, shapes, materials, raw materials, processes, and the like given in the above-described embodiments and examples are merely examples, and numerical values, structures, shapes, materials, raw materials, processes, and the like that are different from these as necessary. May be used.
Further, for example, two or more of the second to fourth embodiments may be combined.

It is a side view which shows the dye-sensitized photoelectric conversion element by 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the dye-sensitized photoelectric conversion element by 1st Embodiment of this invention. 1 is a cross-sectional view showing a dye-sensitized photoelectric conversion element according to a first embodiment of the present invention. It is a top view which shows the photoelectric conversion element module by Example 2 of this invention. It is sectional drawing which shows the photoelectric conversion element module by Example 2 of this invention. It is a basic diagram which shows the incident angle dependence of the light of the maintenance factor of the photoelectric conversion efficiency of the dye-sensitized photoelectric conversion element by Example 1 and Comparative Example 1 of this invention and the photoelectric conversion element module by Example 2 and Comparative Example 2 of FIG. is there. It is a basic diagram which shows the outdoor exposure days dependence of the maintenance rate of the photoelectric conversion efficiency of the dye-sensitized photoelectric conversion element by Example 1 and Comparative Example 1 of this invention and the photoelectric conversion element module by Example 2 and Comparative Example 2 of this invention. . It is sectional drawing which shows the photoelectric conversion element module by Example 3 of this invention. It is sectional drawing which shows the dye-sensitized photoelectric conversion element by 3rd Embodiment of this invention. It is sectional drawing which shows the dye-sensitized photoelectric conversion element by 4th Embodiment of this invention. It is a schematic diagram for demonstrating the manufacturing method of the dye-sensitized photoelectric conversion element by 4th Embodiment of this invention. It is a basic diagram for demonstrating the problem of the conventional dye-sensitized solar cell, and the solution of this problem.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tube, 2 ... Transparent conductive layer, 3 ... Dye sensitized porous semiconductor layer, 4 ... Electrolyte layer, 5 ... Counter electrode, 6 ... Sealing member, 7, 8 ... Lead wire, 9 ... Metal oxide layer, 51 ... Dye, 52 ... Additive

Claims (9)

A dye-sensitized photoconductor having a structure in which a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the center of the tube. Conversion element. The transparent conductive layer, an In-Sn complex oxide, according to claim 1, characterized in that it comprises at least one transparent conductive oxide selected from the group consisting of SnO ₂ and In-Zn composite oxide Dye-sensitized photoelectric conversion element. A method for producing a dye-sensitized photoelectric conversion element having a structure in which a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the central portion of the tube Because
The method for producing a dye-sensitized photoelectric conversion element, wherein the transparent conductive layer is formed on the inner surface of the tube by a wet coating method.   4. The method for producing a dye-sensitized photoelectric conversion element according to claim 3, wherein a spray pyrolysis method is used as the wet coating method. In the photoelectric conversion element module in which a plurality of photoelectric conversion elements are arranged and wired,
At least one of the photoelectric conversion elements is
A dye-sensitized photoelectric conversion element having a structure in which a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the center of the tube. A photoelectric conversion element module.   6. The photoelectric conversion element module according to claim 5, wherein the plurality of photoelectric conversion elements include at least two types of the dye-sensitized photoelectric conversion elements capable of photoelectrically converting light in different wavelength bands. In electronic equipment using dye-sensitized photoelectric conversion elements,
The dye-sensitized photoelectric conversion element is
An electronic apparatus comprising a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer sequentially provided on the inner surface of a tube made of a transparent material, and having a counter electrode inserted in the central portion of the tube. In a moving body using a dye-sensitized photoelectric conversion element,
The dye-sensitized photoelectric conversion element is
A moving body having a structure in which a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the central portion of the tube. In a power generation system using a dye-sensitized photoelectric conversion element,
The dye-sensitized photoelectric conversion element is
A power generation system, characterized in that a transparent conductive layer, a dye-sensitized porous semiconductor layer, and an electrolyte layer are sequentially provided on the inner surface of a tube made of a transparent material, and a counter electrode is inserted in the central portion of the tube.

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