JP2008010189A - Photoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the conversion efficiency of a dye-sensitized photoelectric conversion element. <P>SOLUTION: In the photoelectric conversion element 1 having a charge transfer layer 4 containing an iodine ion and an organic solvent or ionic liquid, conversion efficiency, especially, an open circuit voltage value, a short circuit current value, and a shape factor are enhanced by containing cyanoethylated saccharides in the charge transfer layer 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion element comprising a dye-carrying porous semiconductor layer as a photoelectrode on a conductive transparent substrate, a charge transport layer, a counter electrode, and a substrate.

  A photoelectric conversion element typified by a solar cell is expected as a clean energy source, and a silicon-based pn junction solar cell has already been put into practical use. However, silicon-based solar cells use high-purity materials as raw materials or require high-energy processes such as a high-temperature process of about 1000 [° C.] or a vacuum process during manufacturing, thereby reducing manufacturing costs. This is a big issue.

Against this background, in recent years, wet solar cells, which do not require high-purity materials or high-energy processes and perform charge separation using a potential gradient generated at a solid-liquid interface, have attracted attention. In particular, a so-called dye that aims to improve conversion efficiency by adsorbing a sensitizing dye that absorbs light on the surface of the semiconductor electrode and absorbing visible light having a wavelength longer than the band gap width of the semiconductor electrode with the sensitizing dye. Research on sensitized photoelectric conversion elements has been actively conducted (see Patent Documents 1 and 2 and Non-Patent Document 1).
Japanese Patent No. 2664194 JP 2005-93313 A Abstracts of Annual Meeting of the Electrochemical Society of Japan 2002, 141, 2E27

  However, since the conversion efficiency of a conventional dye-sensitized photoelectric conversion element is about 1%, which is lower than that of a silicon-based solar cell, it is an urgent need to improve the conversion efficiency.

  The present invention has been made to solve the above problems, and an object thereof is to provide a photoelectric conversion element capable of improving the conversion efficiency.

  As a result of intensive research, the inventors of the present invention have, as a result, in a photoelectric conversion element having a charge transport layer containing iodine ions, an organic solvent or an ionic liquid and a cyanoethylated saccharide in the charge transport layer. It has been found that the conversion efficiency, particularly the open-circuit voltage value, the short-circuit current value, and the shape factor are improved by the inclusion of both.

Regarding the improvement of the open circuit voltage value, when a saccharide such as cyanoethylated amylose is present in the electrolyte, the iodine ion I ₃₋ is trapped in the helical structure of the saccharide, and the semiconductor that is the reverse electron transfer destination of the electron in the semiconductor It is conceivable that the open-circuit voltage is improved by apparently lowering the iodine ion concentration in the electrolyte solution in the vicinity of the electrode.

  Regarding the improvement of the short-circuit current value, the addition of saccharides may change the physical properties such as the dielectric constant of the electrolyte, and the current value may be improved by effectively acting on the photocharge separation during light irradiation. Even if the electrolyte is thickened with a saccharide polymer such as a polysaccharide, the amount of gel added will not affect the charge transfer of the electrolyte, so long as the amount of gel is added. The charge transport efficiency of the transport layer is not reduced. That is, thickening due to saccharide gelation does not cause a decrease in the short-circuit current value.

Regarding the improvement of the shape factor, when the saccharide captures the iodine ion I _3- in the charge transport layer, it is considered that the saccharide takes a helical structure and arranges the iodine ion I _3- in a linear shape. This action causes charge hopping between the iodine ions I _3- and the like, and a decrease in the direct current resistance component of the element due to a decrease in the resistance component of the charge transport layer can be considered, which may contribute to an improvement in the shape factor.

  The organic solvent desirably contains any one of acetonitrile, methoxyacetonitrile, 3-methoxypropionitrile, and γ-butyrolactone. The content of amylose, amylopectin, and dextrin in the charge transport layer is preferably in the range of 1 [wt%] to 50 [wt%].

  Hereinafter, with reference to drawings, the manufacturing method of the photoelectric conversion element used as embodiment of this invention is demonstrated.

  As shown in FIG. 1, a photoelectric conversion element 1 according to an embodiment of the present invention has a configuration in which a charge transport layer 4 is sandwiched between a substrate 2 (first substrate) and a substrate 3 (second substrate). The outer periphery of the charge transport layer 4 is sealed with a sealing material. The substrate 2 includes a base material 6, an electrode layer 7 (first electrode) formed on the surface of the base material 6, and a porous semiconductor layer 8 formed on the surface of the electrode layer 7. The semiconductor layer 8 faces the substrate 3. The substrate 3 has a base material 9 and an electrode layer 10 (second electrode, counter electrode) formed on the surface of the base material 9 and faces the substrate 2 on the electrode layer 10 side.

  The charge transport layer 4 is formed of an iodine-based electrolyte solution containing an organic solvent or an ionic liquid as a main medium, and the iodine-based electrolyte solution contains at least one of modified amylose, amylopectin, and dextrin, which will be described later. ing. Amylose, amylopectin, and dextrin are constituents of starch, and starch reacts with iodine to cause a so-called iodine-starch reaction. This reaction is due to the interaction between starch and amylose and iodine atoms at the molecular level, and the details of the structure and the interaction between iodine and amylose remain unclear, but the spiral formed by amylose. It is known that iodine atoms are taken in one row inside the structure. From the above viewpoint, the charge transport layer of the dye-sensitized solar cell may contain iodine as the redox species if the interaction between the saccharide and the redox species contributes to the improvement of the conversion efficiency. desirable.

  As iodine compounds containing iodine, metal iodides such as lithium iodide and potassium iodide may be used. Tetraalkylammonium iodide, ethyltripropylammonium iodide represented by tetrapropylammonium iodide and the like may be used. It is particularly preferable to use asymmetric alkylammonium iodides such as dimethyl and diethyldibutylammonium iodide, quaternary ammonium iodide compounds such as pyridinium iodide, and imidazolium iodide compounds such as dimethylpropylimidazolium iodide. The amount of iodide added is arbitrary, but is preferably in the range of 0.01 to 1 [M]. Moreover, although the quantity of the iodine added is arbitrary, it is desirable to set it as 0.1 [M] or less. The lower limit of the amount of iodine is not particularly specified, but about 0.1 [nM] is appropriate as the lower limit that can be optically quantified.

  When amylose and iodine interact, 6 units of glucose, which is a constituent unit of amylose, includes iodine. Accordingly, even if the sugar has a relatively small molecular weight, such as dextrin and cyclodextrin, a plurality of sugars may interact with iodine atoms. Therefore, the sugar added to the charge transport layer 4 may be other than polysaccharides. Alternatively, a polymer having a polymerization amount exceeding 10,000 may be used. When the polymerization amount is large, the saccharide functions as a gelling agent, and in the case of an organic solvent, the charge transport layer 4 is less likely to volatilize and the durability of the device can be improved. Further, a pyridine derivative, an imidazole derivative, or the like may be added to the charge transport layer 4. For example, 4-tert-butylpyridine, N-methylbenzimidazole, etc. are effective in improving the open circuit voltage of the device.

  An electrolyte can also be used for the charge transport layer 4. In this case, the solvent used for dissolving the electrolyte is preferably a compound that dissolves the redox constituent and is excellent in ion conductivity. As the solvent, any of an aqueous solvent and an organic solvent can be used, but it is desirable to use an organic solvent in order to further stabilize the redox constituent. For example, carbonate compounds such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate and propylene carbonate, ester compounds such as methyl acetate, methyl propionate and γ-butyrolactone, diethyl ether, 1,2-dimethoxyethane, 1,3 -Ether compounds such as dioxosilane, tetrahydrofuran, 2-methyl-tetrahydrofuran, heterocyclic compounds such as 3-methyl-2-oxazodilinone, 2-methylpyrrolidone, nitrile compounds such as acetonitrile, methoxyacetonitrile, propionitrile, sulfolane, didimethyl Examples include aprotic polar compounds such as sulfoxide and dimethylformamide. These can be used alone or in combination of two or more. Among them, carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as γ-butyrolactone, 3-methyl-2-oxazodilinone and 2-methylpyrrolidone, acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, Nitrile compounds such as valeric nitrile are preferred.

  It is also effective to use an ionic liquid for the charge transport layer 4 from the viewpoints of non-volatility and flame retardancy. In this case, known ionic liquids in general can be used, but imidazolium-based, pyridine-based, alicyclic amine-based, aliphatic amine-based, and azonium amine-based ionic liquids, literature (European patents) No. 718288, International Patent Application No. 95/18456, Electrochemical Vol. 65, No. 11, 923 (1997), J. Electrochem. Soc. 143, 10, 3099 (1996), Inorg. Chem. .35, 1168 (1996)) is preferably used.

  Further, when an electrolyte is used for the charge transport layer 4, a gelled electrolyte or a polymer electrolyte can be used. Examples of the gelling agent include a gelling agent using a technique such as a polymer and a polymer crosslinking reaction, a gelling agent based on a polymerizable polyfunctional polymer, and an oil gelling agent. Commonly used gelling electrolytes and polymer electrolytes can be used, such as polyvinylidene fluoride polymers such as polyvinylidene fluoride, acrylic acid polymers such as polyacrylic acid, poly It is preferable to use an acrylonitrile polymer such as acrylonitrile, a polyether polymer such as polyethylene oxide, or a compound having an amide structure in the structure.

  Moreover, it is preferable to make the quantity of the saccharide | sugar or saccharide derivative in the electric charge transport layer 4 into the range of 1-50 [wt%]. The lower limit is not particularly limited, but if it is 1 [wt%] or less, the amount is too small, and the effect of adding saccharides is difficult to be exhibited. On the contrary, if it is 50 [wt%] or more, it is excessively added, and in the case of amylopectin, it is not preferable from the problem of saturation solubility and the problem of thickening of the charge transport layer. If it is in the range of 1 to 50 [wt%], by controlling the molecular weight and substituent of the saccharide or saccharide derivative, a gelled charge transport layer having not only the conversion efficiency of the device but also the desired hardness is constructed. Can do.

  Further, amylose, amylopectin, or dextrin contained in the charge transport layer 4 is modified so as to be soluble in an organic solvent or an ionic liquid. The solubilized sites are the three hydroxyl groups present in the glucose skeleton, which is a structural unit. The substitution rate is not particularly limited as long as the substitution rate can provide solubility in an organic solvent or ionic liquid, but if it is 50% or more, it is effective because the effect of introducing substituents can be more easily obtained. . Further, from the viewpoint of solubility in an organic solvent or ionic liquid, the substituent is preferably a cyanoalkyl group such as a cyanoethyl group. This cyanoethylation makes it soluble in organic solvents or ionic liquids, and the conversion efficiency, particularly open-circuit voltage value, short-circuit current value, and form factor, by the combination of such solvent or liquid and cyanoethylated saccharides Becomes an excellent photoelectric conversion element. Any of the following substituents may be present.

  That is, hydroxypropylated starch, carboxymethylated starch, acetate starch, cationic starch, octenyl succinic acid that has been subjected to etherification, esterification, crosslinking, grafting, enzyme modification, oxidation, acid treatment, etc. for derivatization Starch, phosphate starch, phosphate distarch, glycerol distarch, grafted starch, colored dextrin, maltodextrin may be present. In the case of derivatization, preferred substituents include methyl, ethyl, i-propyl, butyl, t-butyl, octyl, 2-ethylhexyl, 2-methoxyethyl which may be substituted, linear or branched. , Benzyl, trifluoromethyl, cyanomethyl, ethoxycarbonylmethyl, propoxyethyl, 3- (1-octylpyridinium-4-yl) propyl, alkyl such as 3- (1-butyl-3-methylpyridinium-4-yl) propyl Groups, alkenyl groups such as vinyl and allyl, which may be substituted or linear or branched, phenyl, 4-methylphenyl, 3-cyanophenyl, 2- Aryl groups such as chlorophenyl and 2-naphthyl, 4-pyridyl, 2-pyridyl, 1-octyl which may be substituted or condensed Heterocyclic groups such as rupyridinium-4-yl, 2-pyrimidyl, 2-imidazolyl, 2-thiazolyl, nitrogen-containing heterocyclic groups, nitrogen heterocyclic groups in which nitrogen is quaternized, methoxy, ethoxy, butoxy, octyloxy Preferred are alkoxy groups such as acetyloxy and benzoyloxy, alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl, cyano groups, halogens such as chlorine and bromine, more preferably alkyl groups, alkenyl groups and alkoxycarbonyl. Group, cyano group, cyanoalkyl group and halogen. Still more preferred are an alkyl group, an alkenyl group, an alkoxycarbonyl group, a cyano group, and a cyanoalkyl group, and most preferred is a cyanoalkyl group.

  Glass or film is used as the material of the substrate 6, but it is preferable to use a flexible film because it is easy to apply pressure to the semiconductor layer 8. Moreover, since the base material 6 functions as a light incident substrate, it is preferable that it is transparent. Transparent films include recycled cellulose film, diacetate cellulose film, triacetate cellulose film, tetraacetyl cellulose film, polyethylene film, polypropylene film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, polyethylene terephthalate film, polycarbonate film , Polyethylene naphthalate film, polyethersulfone film, polyetherketone film, polysulfone film, polyetherimide film, polyimide film, polyarylate film, cycloolefin polymer film, norbornene resin film, polystyrene film, hydrochloric acid rubber film, nylon Film, polyacrylate film Arm, polyvinyl fluoride film, polytetrafluoroethylene film, and the like can be exemplified. Among these, a polyethylene terephthalate film, a polyethylene naphthalate film, a polyether sulfone film, a polyimide film, a polyarylate film, a cycloolefin polymer film, and a norbornene resin film are preferable because they are tough and have excellent heat resistance. Moreover, if the base material 9 is made to function as a light-incidence board | substrate, metal foil, such as nickel, zinc, titanium, can be used as a film of the base material 6. FIG. When a flexible film is used as the substrate 6, the semiconductor layer 8 can be formed by applying pressure. The type of press used at the time of pressurization is not particularly limited, such as a flat plate press or a roll press, but when a conductive film is used for the substrate 6, the roll press is a roll-to-roll. This is preferable because continuous production is possible.

  The surface resistance of the electrode layer 7 is preferably as low as possible, preferably 200 [Ω / □] or less, more preferably 50 [Ω / □] or less. The lower limit is not particularly limited, but is usually 0.1 [Ω / □]. The light transmittance of the electrode layer 7 is preferably as high as possible, preferably 50 [%] or more, more preferably 80 [%] or more. The film thickness of the electrode layer 7 is preferably in the range of 0.1 to 10 [μm]. Within this range, an electrode film having a uniform thickness can be formed, and light transmittance is not lowered, and sufficient light can be incident on the semiconductor layer 8. When the electrode layer 7 is transparent, light is preferably incident from the electrode layer 7 on the side where the semiconductor layer 8 carrying the sensitizing dye is deposited.

  The particle size of the semiconductor particles constituting the semiconductor layer 8 is desirably in the range of 5 to 1000 [nm], more preferably 10 to 100 [nm]. Within this range, the pore size of the semiconductor layer 8 becomes an appropriate pore size, and the electrolyte sufficiently penetrates into the semiconductor layer 8 to obtain excellent photoelectric conversion characteristics. The film thickness of the semiconductor layer 8 is in the range of 0.1 to 100 [μm], more preferably 1 to 50 [μm], particularly preferably 5 to 30 [μm], and most preferably 10 to 20 [μm]. It is desirable to be within. Within this range, a sufficient photoelectric conversion effect can be obtained, and the transmittance for visible light and near-infrared light does not deteriorate. The semiconductor layer 8 is formed by applying a mixed solution of semiconductor particles and a binder to the surface of the electrode layer 7 using a known method such as a coating method using a doctor blade or a bar coater, a spray method, a dip coating method, a screen printing method, or a spin coating method. If the base material 6 is a glass substrate, it is fired at around 500 [° C.], and if the base material 6 is a film substrate, it can be formed by applying pressure with a press.

Semiconductor materials include metal elements such as Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, Si, and Cr. _oxides, SrTiO _3, CaTiO 3 or the like of the _{perovskite, CdS, ZnS, in 2 S} 3, PbS, Mo 2 S, WS 2, Sb 2 S 3, Bi 2 S 3, ZnCdS 2, Cu 2 S sulfides such as Metal chalcogenides such as CdSe, In ₂ Se ₃ , WSe ₂ , HgS, PbSe, CdTe, GaAs, Si, Se, Cd ₂ P ₃ , Zn ₂ P ₃ , InP, AgBr, PbI ₂ , HgI ₂ , BiI ₃ Can be illustrated. Further, a composite containing at least one or more obtained from the semiconductor material, for example, CdS / TiO ₂ , CdS / AgI, Ag ₂ S / AgI, CdS / ZnO, CdS / HgS, CdS / PbS, ZnO / ZnS, _{CdS / HgS, CdS x / CdSe} 1-x, CdS x / Te 1-x, CdSe x / Te 1-x, ZnS / CdSe, ZnSe / CdSe, CdS / ZnS, TiO 2 / Cd 3 P 2, CdS / Examples thereof include CdSe / Cd _y Zn _1-y S, CdS / HgS / Cds, and the like. Among these, TiO ₂ is preferable in terms of avoiding photodissolution in the electrolytic solution and high photoelectric conversion characteristics.

As the sensitizing dye carried by the semiconductor layer 8, any dye that is commonly used in conventional dye-sensitized photoelectric conversion elements can be used. Specifically, RuL ₂ (H ₂ O) ₂ type ruthenium-cis-diaqua-bipyridyl complex, ruthenium-tris (RuL ₃ ), ruthenium-bis (RuL ₂ ), osnium-tris (OsL ₃ ), osnium- Examples thereof include a bis (OsL ₂ ) type transition metal complex, zinc-tetra (4-carboxyphenyl) porphyrin, iron-exocyanide complex, and phthalocyanine. Organic dyes include 9-phenylxanthene dyes, coumarin dyes, acridine dyes, triphenylmethane dyes, tetraphenylmethane dyes, quinone dyes, azo dyes, indigo dyes, cyanine dyes, merocyanine Examples thereof include system dyes and xanthene dyes. Among these, a ruthenium-bis (RuL ₂ ) derivative is particularly preferable because it has a wide absorption spectrum in the visible light region.

Examples of the method of supporting the sensitizing dye on the semiconductor layer 8 include a method of immersing the substrate 2 in a solution in which the sensitizing dye is dissolved. As the solvent of this solution, any solvent that can dissolve the sensitizing dye, such as water, alcohol, toluene, dimethylformamide, and the like can be used. As the immersion method, heating and refluxing or applying ultrasonic waves can be performed while the substrate 2 is immersed in the sensitizing dye solution for a certain period of time. In order to remove the sensitizing dye remaining on the semiconductor layer 8 without being supported after the dye is supported on the semiconductor layer 8, it is desirable to wash with alcohol or reflux with heating. The amount of the sensitizing dye supported on the semiconductor layer 8 is 1 × 10 ₋₈ to 1 × 10 ₋₆ [mol / cm ₂ ], more preferably 0.1 × 10 _{−7 to} 9.0 × 10 ₋₇ [ mol / cm ₂ ] is desirable. If it is within this range, it is possible to expect a sufficient improvement in photoelectric conversion efficiency economically.

  The base material 9 can use the same material as the base material 6. The transparency of the base material 9 may be either transparent or opaque. However, it is desirable that the base material 9 is transparent in that light can be incident from the substrates on both sides. When a metal foil is used as the film of the substrate 6, the substrate 9 is desirably the above-described translucent film. The electrode layer 7 formed on one surface of the substrate 6 functions as a negative electrode of the photoelectric conversion element 1 and is formed of metal or formed by laminating a conductive material layer on a film. Conductive metal oxides such as metals such as platinum, gold, silver, copper, aluminum, rhodium, and indium, carbon, indium-tin composite oxide, tin oxide doped with antimony, tin oxide doped with fluorine, etc. And composites of these oxides, and materials obtained by coating these oxides with silicon oxide, tin oxide, titanium oxide, zirconium oxide, aluminum oxide or the like.

  The electrode layer 10 functions as a positive electrode of the photoelectric conversion element 1 and can be formed in the same manner as the electrode layer 7 on the side where the semiconductor layer 8 carrying the sensitizing dye is deposited. As the electrode layer 10, it is desirable to use a material having a catalytic action to give electrons to the electrolyte reductant in order to efficiently act as the positive electrode of the photoelectric conversion element 1. As such materials, metals such as platinum, gold, silver, copper, aluminum, rhodium and indium, graphite, carbon nanotubes, carbon materials such as carbon carrying platinum, indium-tin composite oxide, antimony doped Examples include conductive metal oxides such as tin oxide and fluorine-doped tin oxide, and conductive polymers such as polyethylenedioxythiophene, polypyrrole, and polyaniline. Among them, platinum, graphite, polyethylenedioxythiophene, etc. Particularly preferred. In addition, a transparent conductive film may be provided on the surface side of the base material 9 on which the electrode layer 10 is deposited, and the transparent conductive film can be formed from the same material as the electrode layer 7. In this case, it is desirable that the electrode layer 10 is also transparent. If the electrode layer 10 is transparent, light may be irradiated from the electrode layer 10 side or both sides. This is effective when light irradiation is expected from both the front and back surfaces of the photoelectric conversion element 1 due to the influence of reflected light or the like.

  Next, the photoelectric conversion element according to the present invention will be specifically described based on examples.

[Example 1]
In Example 1, a high-purity titanium oxide powder having an average primary particle size of 20 [nm] was first dispersed in ethyl cellulose to produce a screen printing paste as the first paste. Next, a high-purity titanium oxide powder having an average primary particle size of 20 [nm] and an average primary particle size of 400 [nm] is dispersed in ethyl cellulose to produce a screen printing paste as a second paste. did. Next, the first paste is applied onto a 1 mm thick conductive glass substrate (Asahi Glass, F-SnO ₂ , surface resistance 10 [Ω / □]) and dried. By baking in air at 500 [° C.] for 30 minutes, a porous titanium oxide film having a thickness of 10 [μm] was formed on the substrate. Next, the second paste is applied and dried on the porous titanium oxide film, and the obtained dried product is baked in the air at 500 [° C.] for 30 minutes to obtain a thickness on the porous titanium oxide film. A 4 [μm] titanium oxide film was formed. Next, the substrate was dipped in a sensitizing dye solution represented by [Ru (4,4′-dicarboxyl-2,2′-pipyridine) _2- (NCS) ₂ ] and was kept in the dark at room temperature for 24 hours. The pigment | dye adsorption process was performed by leaving still and the board | substrate 2 was formed. Next, the substrate 3 was formed by attaching platinum on the surface of a conductive glass substrate (manufactured by Asahi Glass, fluorine-doped SnO ₂ , surface resistance 10 [Ω / □]) by sputtering. Next, after placing a hot-melt adhesive Himiran as a sealing material cut so as to surround the periphery of the titanium oxide film of the substrate 2 on the platinum of the substrate 3, a hole was drilled with a diamond drill on the top thereof. The substrate 3 was placed and pressed while heating to bond the substrate 2 and the substrate 3 together. Next, 0.5 [mol / dm ₃ ] dimethylpropylimidazolium iodide, 0.01 [mol / dm ₃ ] lithium iodide, 0.02 [mol / dm] as the charge transport layer 4 from the holes of the substrate 3. dm ₃ ] iodine, 0.5 [mol / dm ₃ ] 4-tert-butylpyridine, and amylose as a saccharide (mixed with amylopectin, cyanoethylated substitution rate of 80 [%] or more) acetonitrile containing 10 wt% After injecting the electrolyte solution using, the hole was sealed to produce the photoelectric conversion element of Example 1.

[Example 2]
In Example 2, 0.5 [mol / dm ₃ ] dimethylpropylimidazolium iodide, 0.01 [mol / dm ₃ ] lithium iodide, 0.03 [mol / dm ₃ ] iodine, Example 1 except that an electrolyte using γ-butyrolactone containing 5 [mol / dm ₃ ] of 4-tert-butylpyridine and cyanoethylated starch (VISGUM12) 3 [wt%] was used as the charge transport layer 4. The photoelectric conversion element of Example 2 was produced by performing the same process.

Example 3
In Example 3, 0.5 [mol / dm ₃ ] dimethylpropylimidazolium iodide, 0.01 [mol / dm ₃ ] lithium iodide, 0.03 [mol / dm ₃ ] iodine, Example 1 except that an electrolyte using γ-butyrolactone containing 5 [mol / dm ₃ ] of 4-tert-butylpyridine and cyanoethylated starch (VISGUM12) 30 [wt%] was used as the charge transport layer 4. The photoelectric conversion element of Example 3 was produced by performing the same process.

Example 4
In Example 4, 0.5 [mol / dm ₃ ] dimethylpropylimidazolium iodide, 0.01 [mol / dm ₃ ] lithium iodide, 0.03 [mol / dm ₃ ] iodine, Example 1 except that an electrolyte using γ-butyrolactone containing 5 [mol / dm ₃ ] of 4-tert-butylpyridine and cyanoethylated starch (VISGUM12) 10 [wt%] was used as the charge transport layer 4. The photoelectric conversion element of Example 4 was produced by performing the same process.

[Comparative Example 1]
In Comparative Example 1, 0.5 [mol / dm ₃ ] dimethylpropylimidazolium iodide, 0.01 [mol / dm ₃ ] lithium iodide, 0.02 [mol / dm ₃ ] iodine, Example except that electrolyte solution using 5 [mol / dm ₃ ] 4-tert-butylpyridine and starch (made by Wako Pure Chemical Industries, Ltd.) 2 [wt%] was used as the charge transport layer 4 The photoelectric conversion element of the comparative example 1 was produced by performing the same process as 1.

[Comparative Example 2]
In Comparative Example 2, 0.5 [mol / dm ₃ ] dimethylpropylimidazolium iodide, 0.01 [mol / dm ₃ ] lithium iodide, 0.02 [mol / dm ₃ ] iodine, and 0 The photoelectric conversion element of Comparative Example 2 was obtained by carrying out the same treatment as in Example 1 except that the electrolytic solution using acetonitrile containing 5- [mol / dm ₃ ] 4-tert-butylpyridine was used as the charge transport layer 4. Produced.

[Comparative Example 3]
In Comparative Example 3, acetonitrile containing 0.5 [mol / dm ₃ ] potassium iodide, 0.02 [mol / dm ₃ ] iodine, and starch (manufactured by Wako Pure Chemical Industries, Ltd.) 2 [wt%] The photoelectric conversion element of the comparative example 3 was produced by performing the same process as Example 1 except having made the electrolyte solution using this into the electric charge transport layer 4.

[Evaluation of solar cell output]
The photoelectric conversion elements of Examples 1 to 4 and Comparative Examples 1 to 3 were irradiated with light having an illuminance of 1 [mW / cm ₂ ] using a xenon lamp (pseudo sunlight spectrum, AM1.5). The solar cell output was measured. And the relative value of the solar cell output of each photoelectric conversion element when the solar cell output of the photoelectric conversion element of the comparative example 2 was set to 100 was computed. The calculation results are shown in Table 1.

  As is apparent from Table 1, it can be seen that the solar cell outputs of the photoelectric conversion elements of Examples 1 to 4 are relatively larger than the solar cell outputs of the photoelectric conversion elements of Comparative Examples 1 to 3. From this, by using an organic solvent such as acetonitrile or γ-butyrolactone, by adding saccharides to the charge transport layer, a higher output characteristic is obtained compared to a system in which saccharides are not added or a system in which saccharides are added to an aqueous electrolyte solution. It became clear that it was obtained.

  As mentioned above, although the embodiment to which the invention made by the present inventors was applied has been described, the present invention is not limited by the description and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.

It is sectional drawing which shows the structure of the photoelectric conversion element used as embodiment of this invention.

Explanation of symbols

1: Photoelectric conversion element 2, 3: Substrate 4: Charge transport layer 6, 9: Base material 7, 10: Electrode layer 8: Semiconductor layer 11: Heating device 12: Cooling device

Claims (3)

Charge transport including a first electrode to which a semiconductor carrying a sensitizing dye is attached, a second electrode opposed to the semiconductor, and iodine sandwiched between the first electrode and the second electrode A photoelectric conversion element having a layer,
The charge transport layer includes at least one of an organic solvent and an ionic liquid, and includes at least one of amylose, amylopectin, and dextrin in which at least part of the hydroxyl terminal is cyanoethylated and modified to be liquid soluble. The photoelectric conversion element characterized by the above-mentioned.   2. The photoelectric conversion element according to claim 1, wherein the organic solvent includes any one of acetonitrile, methoxyacetonitrile, 3-methoxypropionitrile, and γ-butyrolactone.   3. The photoelectric conversion device according to claim 1, wherein the content of the modified amylose, amylopectin, and dextrin in the charge transport layer is in the range of 1 [wt%] to 50 [wt%]. A photoelectric conversion element characterized by being inside.

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