JP6576784B2 - Electrolyte for photoelectric conversion element and photoelectric conversion element using the same - Google Patents

Description

  The present invention relates to an electrolyte for a photoelectric conversion element and a photoelectric conversion element using the same.

  The dye-sensitized photoelectric conversion element is a next-generation photoelectric conversion element which has been developed by Gretzell et al. In Switzerland and has been attracting attention because it has advantages such as high photoelectric conversion efficiency and low manufacturing cost.

  Such a photoelectric conversion element using a dye generally includes at least one photoelectric conversion cell, and the photoelectric conversion cell includes a first electrode substrate, a second electrode substrate facing the first electrode substrate, An oxide semiconductor layer provided on the one electrode substrate or the second electrode substrate and an electrolyte provided between the first electrode substrate and the second electrode substrate are provided.

  In order for such a photoelectric conversion element to obtain excellent photoelectric conversion characteristics, for example, it is important to improve the open circuit voltage. For example, in Patent Document 1 below, an oxidation-reduction pair is used to improve the open circuit voltage. It is disclosed to add t-butylpyridine to the electrolyte contained.

JP 2005-327515 A

  However, the electrolyte described in Patent Document 1 has the following problems.

  That is, when the electrolyte described in Patent Document 1 is used as an electrolyte contained in a photoelectric conversion cell of a photoelectric conversion element, it can provide an excellent open voltage to the photoelectric conversion element, but still has an improvement in open voltage. There was room for improvement. Moreover, the electrolyte described in Patent Document 1 has room for improvement in terms of improving the durability of the photoelectric conversion element. Therefore, there has been a demand for an electrolyte for a photoelectric conversion element that can not only improve the open-circuit voltage of the photoelectric conversion element but also improve the durability.

  This invention is made | formed in view of the said situation, It aims at providing the electrolyte for photoelectric conversion elements which can improve the open circuit voltage and durability of a photoelectric conversion element, and a photoelectric conversion element using the same. To do.

  In order to solve the above-mentioned problems, the present inventor has intensively studied paying attention to the composition of the electrolyte. As a result, the present inventor considered the reason why the electrolyte described in Patent Document 1 could not solve the above problem as follows. That is, when t-butylpyridine is contained in the electrolyte, t-butylpyridine exhibits a high basicity, and thus reacts with water molecules mixed in the electrolyte to generate hydroxide ions (OH-). This hydroxide ion degrades the dye by nucleophilic reaction. For this reason, this inventor thought that durability of a photoelectric conversion element could not be improved with t-butylpyridine. Therefore, as a result of intensive studies, the present inventor has found that the above problem can be solved by adjusting the base metal oxide in the electrolyte to a predetermined concentration, and has completed the present invention.

That is, the present invention includes a redox couple and a base metal oxide, and the concentration of the base metal oxide having the maximum concentration among the base metal oxides is 1 to 500 ppm by mass (excluding 500 ppm by mass) . It is an electrolyte for photoelectric conversion elements.

  According to the electrolyte for a photoelectric conversion element of the present invention, the open-circuit voltage and durability of the photoelectric conversion element can be improved.

  The inventor presumes the reason why such an effect is obtained as follows. That is, when the electrolyte of the present invention is used as an electrolyte of a photoelectric conversion cell included in a photoelectric conversion element, the base metal oxide exhibits a low basicity and thus hardly reacts with water molecules mixed in the electrolyte. For this reason, hydroxide ions (OH-) are less likely to be generated, and the deterioration of the pigment due to hydroxide ions is less likely to occur. On the other hand, since the base metal oxide has oxygen atoms in the molecule, it easily binds to the oxide semiconductor layer and efficiently covers the surface of the oxide semiconductor layer that becomes a leakage site of current, thereby opening the open voltage of the photoelectric conversion element. Can be improved. And it may be possible to improve the durability and open circuit voltage of the photoelectric conversion element in a balanced manner by setting the concentration of the base metal oxide having the maximum concentration of 1 to 500 mass ppm among the base metal oxides. The inventor speculates.

  In the photoelectric conversion element electrolyte, the base metal oxide is bismuth oxide, zinc oxide, copper oxide, iron oxide, manganese oxide, lead oxide, tin oxide, nickel oxide, aluminum oxide, tungsten oxide, molybdenum oxide, magnesium oxide. Selected from the group consisting of cobalt oxide, cadmium oxide, titanium oxide, zirconium oxide, antimony oxide, beryllium oxide, chromium oxide, germanium oxide, vanadium oxide, gallium oxide, hafnium oxide, indium oxide, niobium oxide, rhenium oxide, and thallium oxide It is preferable to be composed of at least one selected from the above.

  In this case, compared with the case where a base metal oxide is comprised with base metal oxides other than the said base metal oxide, the open circuit voltage of a photoelectric conversion element can be improved more.

  Or in the said electrolyte for photoelectric conversion elements, the said base metal oxide may contain at least 1 sort (s) selected from the group which consists of a bismuth oxide, a zinc oxide, and a tin oxide at least.

  In this case, the open-circuit voltage of the photoelectric conversion element can be further improved as compared with the case where the base metal oxide does not contain at least one selected from the group consisting of bismuth oxide, zinc oxide, and tin oxide.

  In the said electrolyte for photoelectric conversion elements, it is preferable that the said base metal oxide contains the bismuth oxide.

  In this case, the open-circuit voltage of the photoelectric conversion element can be further improved as compared with the case where the base metal oxide does not contain bismuth oxide.

  In the said electrolyte for photoelectric conversion elements, it is preferable that the density | concentration of the base metal oxide whose density | concentration is the maximum is 2-100 mass ppm among the said base metal oxides.

  In this case, the open circuit voltage of the photoelectric conversion element can be further improved as compared with the case where the concentration of the base metal oxide having the maximum concentration out of the above range.

  The present invention also includes at least one photoelectric conversion cell, wherein the photoelectric conversion cell includes a first electrode substrate, a second electrode substrate facing the first electrode substrate, and the first electrode substrate or the second electrode. An oxide semiconductor layer provided on a substrate and an electrolyte provided between the first electrode substrate and the second electrode substrate, wherein the electrolyte is a photoelectric conversion element made of the above-described electrolyte for a photoelectric conversion element.

  According to the photoelectric conversion element of the present invention, the open circuit voltage and durability can be improved.

  In the photoelectric conversion element, at least one of the first electrode substrate and the second electrode substrate has a glass substrate in contact with the electrolyte, and the glass substrate is a base metal oxide common to the base metal oxide in the electrolyte. It is preferable to contain a product.

  In this case, the power generation characteristics of the photoelectric conversion element are further improved. About this reason, this inventor has guessed that it may be because it can suppress that the base metal oxide in electrolyte adsorb | sucks to a glass substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the electrolyte for photoelectric conversion elements which can improve the open circuit voltage of a photoelectric conversion element, and a photoelectric conversion element using the same are provided. As a result, the photoelectric conversion efficiency can be improved. Moreover, according to this invention, the electrolyte for photoelectric conversion elements which can improve the durability of a photoelectric conversion element, and a photoelectric conversion element using the same are provided.

It is sectional drawing which shows one Embodiment of the photoelectric conversion element of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view showing one embodiment of the photoelectric conversion element of the present invention.

  As shown in FIG. 1, the photoelectric conversion element 100 includes a single photoelectric conversion cell 60, and the photoelectric conversion cell 60 includes a first electrode substrate 10 and a second electrode substrate facing the first electrode substrate 10. 20, an oxide semiconductor layer 30 provided on the first electrode substrate 10, and an annular sealing portion 40 that connects the first electrode substrate 10 and the second electrode substrate 20. A cell space formed by the first electrode substrate 10, the second electrode substrate 20, and the sealing portion 40 is filled with an electrolyte 50.

  The first electrode substrate 10 includes a transparent substrate 11 and a transparent conductive substrate 15 including a transparent conductive layer 12 provided on the transparent substrate 11.

  The second electrode substrate 20 includes a conductive substrate 21 and a catalyst layer 22 that is provided on the transparent conductive substrate 15 side of the conductive substrate 21 and contributes to the reduction of the electrolyte 50.

  The oxide semiconductor layer 30 is disposed inside the sealing portion 40. A dye is adsorbed on the oxide semiconductor layer 30.

  The electrolyte 50 includes a redox couple and a base metal oxide. And the density | concentration of the base metal oxide whose density | concentration is the largest among base metal oxides is 1-500 mass ppm.

  According to the photoelectric conversion element 100, the open circuit voltage and durability can be improved because the electrolyte 50 has the above configuration.

  Next, the 1st electrode substrate 10, the 2nd electrode substrate 20, the oxide semiconductor layer 30, the sealing part 40, the electrolyte 50, and the pigment | dye are demonstrated in detail.

<First electrode substrate>
As described above, the first electrode substrate 10 is composed of the transparent conductive substrate 15, and the transparent conductive substrate 15 is provided on the transparent substrate 11 and the transparent substrate 11, and the transparent conductive layer that is the first electrode. 12.

  The material which comprises the transparent substrate 11 should just be a transparent material, for example, As such a transparent material, glass, such as borosilicate glass, soda lime glass, white plate glass, quartz glass, polyethylene terephthalate (PET), for example , Polyethylene naphthalate (PEN), polycarbonate (PC), and polyethersulfone (PES).

  Here, when the transparent substrate 11 is a glass substrate made of glass, the transparent substrate 11 may not be in contact with the electrolyte 50, but is in contact with the electrolyte 50 as shown in FIG. Also good. When the transparent substrate 11 is in contact with the electrolyte 50, the transparent substrate 11 preferably contains a base metal oxide common to the base metal oxide in the electrolyte 50. In this case, it can suppress that the base metal oxide in the electrolyte 50 adsorb | sucks to the transparent substrate 11 comprised with a glass substrate, As a result, the electric power generation characteristic of the photoelectric conversion element 100 improves more. Here, the base metal oxide contained in the transparent substrate 11 and the base metal oxide contained in the electrolyte 50 are preferably the same.

  The thickness of the transparent substrate 11 is appropriately determined according to the size of the photoelectric conversion element 100 and is not particularly limited, but may be in the range of 50 to 40,000 μm, for example.

  Examples of the material constituting the transparent conductive layer 12 include conductive metal oxides such as tin-added indium oxide (ITO), tin oxide (SnO 2), and fluorine-added tin oxide (FTO). The transparent conductive layer 12 may be a single layer or a laminate of a plurality of layers made of different conductive metal oxides. When the transparent conductive layer 12 is composed of a single layer, the transparent conductive layer 12 is preferably composed of FTO because it has high heat resistance and chemical resistance. The thickness of the transparent conductive layer 12 may be in the range of 0.01 to 2 μm, for example.

<Second electrode substrate>
As described above, the second electrode substrate 20 is provided on the conductive substrate 21 serving as the substrate and the second electrode, and the conductive substrate 21 is provided on the first electrode substrate 10 side and contributes to the reduction of the electrolyte 50. The catalyst layer 22 is provided.

  The conductive substrate 21 is made of a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, tungsten, aluminum, and stainless steel. Further, the conductive substrate 21 may be formed of a laminate in which the substrate and the second electrode are separated and a transparent conductive layer made of a conductive oxide such as ITO or FTO is formed as the second electrode on the transparent substrate 11 described above. Good.

  Here, when the transparent substrate 11 of the conductive substrate 21 is a glass substrate made of glass, the transparent substrate 11 may not be in contact with the electrolyte 50, but may be in contact with the electrolyte 50. . When the transparent substrate 11 of the conductive substrate 21 is in contact with the electrolyte 50, the transparent substrate 11 of the conductive substrate 21 preferably contains a base metal oxide common to the base metal oxide in the electrolyte 50. In this case, it can suppress that the base metal oxide in the electrolyte 50 adsorb | sucks to the transparent substrate 11 comprised with a glass substrate, As a result, the electric power generation characteristic of the photoelectric conversion element 100 improves more. Here, the base metal oxide contained in the transparent substrate 11 and the base metal oxide contained in the electrolyte 50 are preferably the same.

  The thickness of the conductive substrate 21 is appropriately determined according to the size of the photoelectric conversion element 100 and is not particularly limited, but may be, for example, 0.005 to 4 mm.

  The catalyst layer 22 is composed of platinum, a carbon-based material, a conductive polymer, or the like. Here, carbon nanotubes are suitably used as the carbon-based material. In addition, the 2nd electrode substrate 20 does not need to have the catalyst layer 22 when the electroconductive board | substrate 21 has a catalyst function (for example, when containing carbon etc.).

<Oxide semiconductor layer>
The oxide semiconductor layer 30 is composed of oxide semiconductor particles. Examples of the oxide semiconductor particles include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ O ₅ ), strontium titanate (SrTiO ₃ ), and tin oxide (SnO ₂ ). , Indium oxide (In ₃ O ₃ ), zirconium oxide (ZrO ₂ ), thallium oxide (Ta ₂ O ₅ ), lanthanum oxide (La ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), holmium oxide (Ho ₂ O) ₃ ), bismuth oxide (Bi ₂ O ₃ ), cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), or two or more thereof. The thickness of the oxide semiconductor layer 30 may be, for example, 0.1 to 100 μm.

<Sealing part>
Examples of the sealing portion 40 include thermoplastic resins such as modified polyolefin resins and vinyl alcohol polymers, and resins such as ultraviolet curable resins. Examples of modified polyolefin resins include ionomers, ethylene-vinyl acetic anhydride copolymers, ethylene-methacrylic acid copolymers, and ethylene-vinyl alcohol copolymers. These resins can be used alone or in combination of two or more.

<Electrolyte>
As described above, the electrolyte 50 includes a redox couple and a base metal oxide.

<Redox pair>
Examples of the redox pair include, in addition to I ⁻ / I ₃ ⁻ , redox pairs such as combinations of halide ions such as Br ⁻ / Br ₃ ^— and polyhalide ions, zinc complexes, iron complexes, and cobalt complexes. .

  When the redox pair is composed of a combination of the halide ion and the polyhalide ion, the redox pair is formed by a halogen and a halide salt. In this case, the halogen and the halide salt preferably have the same halogen atom, but may have different halogen atoms.

When a redox pair comprising a combination of halide ions and polyhalide ions is included, the concentration of polyhalide ions is preferably 0.006M or less. In this case, since the concentration of the polyhalide ions that carry electrons is low, the leakage current that has a large influence under a low illumination environment can be further reduced. For this reason, compared with the case where the density | concentration of polyhalide ion exceeds 0.006M, the more excellent open circuit voltage can be provided with respect to the photoelectric conversion element 100. FIG. The concentration of polyhalide ions is more preferably greater than 0M and not greater than 6 × 10 ⁻⁶ M, and even more preferably greater than 0M and not greater than 6 × 10 ⁻⁸ M.

(Base metal oxide)
The density | concentration in the electrolyte 50 of the base metal oxide in which the density | concentration in the electrolyte 50 is the largest among base metal oxides should just be 1-500 ppm. In this case, the electrolyte 50 has an open-circuit voltage and durability of the photoelectric conversion element 100 as compared with the case where the concentration of the base metal oxide in the electrolyte 50, which is the maximum concentration of the base metal oxide, is out of the above range. Can be improved.

  The concentration of the base metal oxide in the electrolyte 50 having the maximum concentration in the electrolyte 50 among the base metal oxides is preferably 2 to 100 ppm by mass, and more preferably 10 to 100 ppm by mass. In this case, the electrolyte 50 has a higher open-circuit voltage than that of the photoelectric conversion element 100 as compared with a case where the concentration of the base metal oxide having the maximum concentration in the electrolyte 50 is out of the range of 2 to 100 ppm by mass. Can be improved.

  Examples of the base metal oxide include bismuth oxide, zinc oxide, copper oxide, iron oxide, manganese oxide, lead oxide, tin oxide, nickel oxide, aluminum oxide, tungsten oxide, molybdenum oxide, magnesium oxide, cobalt oxide, cadmium oxide, and oxide. Examples include titanium, zirconium oxide, antimony oxide, beryllium oxide, chromium oxide, germanium oxide, vanadium oxide, gallium oxide, hafnium oxide, indium oxide, niobium oxide, rhenium oxide, and thallium oxide. These can be used alone or in combination of two or more.

  Alternatively, the base metal oxide may be configured to include at least one selected from the group consisting of bismuth oxide, zinc oxide, and tin oxide. In this case, in the electrolyte 50, the base metal oxide other than at least one selected from the group consisting of the bismuth oxide, zinc oxide and tin oxide is selected from the group consisting of the bismuth oxide, zinc oxide and tin oxide. The electrolyte 50 can further improve the open-circuit voltage of the photoelectric conversion element 100 as compared with the case where it is contained at the same concentration as at least one kind.

  Here, the base metal oxide is preferably configured to contain bismuth oxide. In this case, compared with the case where the base metal oxide other than bismuth oxide is contained in the electrolyte 50 at the same concentration as the bismuth oxide, the open-circuit voltage of the photoelectric conversion element 100 can be further improved. Here, the base metal oxide having the maximum concentration among the base metal oxides is preferably bismuth oxide.

(solvent)
The electrolyte 50 may further contain an organic solvent as a solvent. As an organic solvent, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, valeronitrile, pivalonitrile, glutaronitrile, methacrylonitrile, isobutyronitrile, Phenylacetonitrile, acrylonitrile, succinonitrile, oxalonitrile, pentanitrile, adiponitrile and the like can be used. These may be used alone or in combination of two or more.

  Further, an ionic liquid may be used as the solvent of the electrolyte 50 instead of the organic solvent. As the ionic liquid, for example, a known iodine salt such as a pyridinium salt, an imidazolium salt, or a triazolium salt, and a room temperature molten salt that is in a molten state near room temperature is used. Examples of such room temperature molten salts include 1-hexyl-3-methylimidazolium iodide, 1-ethyl-3-propylimidazolium iodide, dimethylimidazolium iodide, ethylmethylimidazolium iodide, and dimethylpropyl. Imidazolium iodide, butylmethylimidazolium iodide, or methylpropyl imidazolium iodide is preferably used.

  When the redox couple is formed by the halogen and the halide salt, the ionic liquid can also function as a halide salt.

  Further, as the solvent of the electrolyte 50, a mixture of the ionic liquid and the organic solvent may be used instead of the organic solvent.

(Other)
An additive can be added to the electrolyte 50. Examples of the additive include benzimidazoles such as 1-methylbenzimidazole (NMB) and 1-butylbenzimidazole (NBB), LiI, I2, and guanidinium thiocyanate. Among them, benzimidazole is preferable as an additive.

Furthermore, as the electrolyte 50, a nanocomposite gel electrolyte which is a pseudo-solid electrolyte obtained by kneading nanoparticles such as SiO ₂ , TiO ₂ , and carbon nanotubes with the above electrolyte may be used, and polyvinylidene fluoride may be used. Alternatively, an electrolyte gelled with an organic gelling agent such as a polyethylene oxide derivative or an amino acid derivative may be used.

<Dye>
Examples of the dye include photosensitizing dyes such as ruthenium complexes having a ligand including a bipyridine structure and a terpyridine structure, organic dyes such as porphyrin, eosin, rhodamine and merocyanine, and organic-inorganic such as lead halide perovskite. Examples include complex dyes. Here, when a photosensitizing dye is used as the dye, the photoelectric conversion element 100 is a dye-sensitized photoelectric conversion element. Among the above dyes, a ruthenium complex having a ligand containing a bipyridine structure or a terpyridine structure is preferable. In this case, more excellent photoelectric conversion characteristics can be imparted to the photoelectric conversion element 100.

  Next, a method for manufacturing the above-described photoelectric conversion element 100 will be described.

  First, a first electrode substrate 10 composed of a transparent conductive substrate 15 formed with a transparent conductive layer 12 is prepared on one transparent substrate 11.

  As a method for forming the transparent conductive layer 12, a sputtering method, a vapor deposition method, a spray pyrolysis method, a CVD method, or the like is used.

  Next, the oxide semiconductor layer 30 is formed on the transparent conductive layer 12. The oxide semiconductor layer 30 is formed by printing a porous oxide semiconductor layer forming paste containing oxide semiconductor particles, followed by firing.

  The oxide semiconductor layer forming paste includes a resin such as polyethylene glycol and a solvent such as terpineol in addition to the oxide semiconductor particles described above.

  As a method for printing the oxide semiconductor layer forming paste, for example, a screen printing method, a doctor blade method, a bar coating method, or the like can be used.

  The firing temperature varies depending on the material of the oxide semiconductor particles, but is usually 350 to 600 ° C., and the firing time also varies depending on the material of the oxide semiconductor particles, but is usually 1 to 5 hours.

  In this way, a working electrode is obtained.

  Next, the dye is adsorbed on the surface of the oxide semiconductor layer 30 of the working electrode. For this purpose, the working electrode is immersed in a solution containing a dye, and after the dye is adsorbed to the oxide semiconductor layer 30, excess dye is washed away with the solvent component of the solution and dried. A dye may be adsorbed on the oxide semiconductor layer 30. However, the dye may be adsorbed to the oxide semiconductor layer 30 by applying a solution containing the dye to the oxide semiconductor layer 30 and then drying the solution.

  Next, the electrolyte 50 is prepared. The electrolyte 50 can be obtained, for example, by adding a solid base metal oxide to an electrolytic solution containing a redox pair. Alternatively, the electrolyte 50 can be obtained by, for example, dissolving halogen, a halide salt that forms a redox pair with the halogen, and a solid base metal oxide in a solvent. At this time, the concentration of the base metal oxide having the maximum concentration among the base metal oxides in the electrolyte 50 is set to 1 to 500 ppm.

  Next, the electrolyte 50 is disposed on the oxide semiconductor layer 30. The electrolyte 50 can be disposed by a coating method.

  Next, an annular sealing portion forming body is prepared. The sealing part forming body can be obtained, for example, by preparing a sealing resin film and forming one rectangular opening in the sealing resin film.

  Then, the sealing portion forming body is bonded onto the first electrode substrate 10. At this time, adhesion of the sealing portion forming body to the first electrode substrate 10 can be performed, for example, by heating and melting the sealing portion forming body.

  Next, after preparing the 2nd electrode substrate 20, and arrange | positioning so that the opening of a sealing part formation body may be plugged up, it bonds together with a sealing part formation body. At this time, the sealing portion forming body may be bonded to the second electrode substrate 20 in advance, and the sealing portion forming body may be bonded to the sealing portion forming body on the first electrode substrate 10 side. The bonding of the second electrode substrate 20 to the sealing portion forming body may be performed under atmospheric pressure or under reduced pressure, but is preferably performed under reduced pressure.

  As described above, the photoelectric conversion element 100 including one photoelectric conversion cell is obtained.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the oxide semiconductor layer 30 is provided on the first electrode substrate 10, but the photoelectric conversion element may have a structure in which the oxide semiconductor layer 30 is provided on the second electrode substrate 20. In this case, the catalyst layer is provided on the transparent conductive layer 12 of the first electrode substrate 10, and the second electrode substrate 20 does not have a catalyst layer.

  Moreover, in the said embodiment, although the 1st electrode substrate 10 is comprised on the transparent substrate 11 and the transparent substrate 11, and is comprised with the transparent conductive layer 12 which is a 1st electrode, the 1st electrode substrate 10 is And an insulating substrate and a plurality of metal wires that are provided on one surface side of the insulating substrate and that are the first electrodes. Here, the periphery of each of the plurality of metal wires may be covered with an oxide semiconductor layer.

  Moreover, in the said embodiment, although the photoelectric conversion element was comprised by the one photoelectric conversion cell 60, the photoelectric conversion element may be provided with two or more photoelectric conversion cells 60. FIG.

  Furthermore, in the above-described embodiment, the photoelectric conversion element 100 does not have a current collection wiring containing silver or the like on the transparent conductive layer 12, but the photoelectric conversion element 100 has a current collection wiring on the transparent conductive layer 12. You may do it. Here, when the current collector wiring is in contact with the electrolyte 50, the current collector wiring is preferably covered with a wiring protective layer from the viewpoint of sufficiently suppressing the corrosion of the current collector wiring. The wiring protective layer is made of, for example, glass or insulating resin.

  Furthermore, in the above embodiment, the first electrode substrate 10 and the second electrode substrate 20 are joined by the sealing portion 40, but the electrolyte 50 is impregnated with the first electrode substrate 10 and the second electrode substrate 20. When the porous insulating layer is sandwiched, the first electrode substrate 10 and the second electrode substrate 20 may not be joined by the sealing portion 40. In this case, an insulating base material is provided on the opposite side of the second electrode substrate 20 to the first electrode substrate 10, and the insulating base material and the first electrode substrate 10 can be joined at the sealing portion. preferable.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

(Examples 1-78, Comparative Examples 1-26, Comparative Example A and Comparative Example B)
<Preparation of electrolyte for photoelectric conversion element>
Addition of base metal oxide or t-butylpyridine to 3-methoxypropionitrile (MPN) solution containing iodine 0.002M, 1,2-dimethyl-3-propylimidazolium iodide (DMPImI) 0.6M Were added so as to have concentrations shown in Tables 1 to 13 (unit: mass ppm) to prepare an electrolyte.

<Production of photoelectric conversion element>
First, a transparent conductive substrate formed by forming a transparent conductive layer made of FTO having a thickness of 1 μm on a transparent substrate made of glass of 30 mm × 20 mm × 2 mm (thickness) was prepared as a first electrode substrate.

  Next, on the transparent conductive layer of the first electrode substrate, an oxide semiconductor layer forming paste containing titania is screen-printed to a size of 5 mm × 5 mm, dried, and then baked at 500 ° C. for 1 hour. . Thus, a working electrode having an oxide semiconductor layer having a size of 5 mm × 5 mm × 40 μm (thickness) was obtained.

  Next, the working electrode was immersed in the dye solution for a whole day and night, and then taken out and dried to adsorb the dye to the oxide semiconductor layer. The dye solution was prepared by dissolving a photosensitizing dye composed of Z907 in a 1-propanol solvent so that its concentration was 0.2 mM.

  Next, the electrolyte prepared as described above was applied on the oxide semiconductor layer.

  Next, the sealing part formation body for forming a sealing part was prepared. The sealing portion forming body is prepared by preparing a single sealing resin film made of 10 mm × 10 mm × 50 μm ionomer (trade name: High Milan, Mitsui / DuPont Polychemical Co., Ltd.) Obtained by forming a square opening. At this time, the opening had a size of 6 mm × 6 mm × 50 μm.

  And after mounting this sealing part formation body on a working electrode, the sealing part formation body was adhere | attached on the working electrode by heat-melting.

  Next, a counter electrode as a second electrode substrate was prepared. The counter electrode was prepared by forming a catalyst layer made of platinum having a thickness of 10 nm by sputtering on a 30 mm × 20 mm × 50 μm (thickness) titanium foil. Further, another sealing part forming body was prepared, and this sealing part forming body was adhered to the surface of the counter electrode facing the working electrode in the same manner as described above.

  And the sealing part formation body adhere | attached on the working electrode and the sealing part formation body adhere | attached on the counter electrode were made to oppose, and the sealing part formation bodies were piled up. And in this state, the sealing part forming body was heated and melted while being pressurized. Thus, a sealing portion was formed between the working electrode and the counter electrode.

  Thus, a photoelectric conversion element composed of one photoelectric conversion cell was obtained.

<Evaluation of characteristics>
(1) Evaluation of open circuit voltage For the photoelectric conversion elements of Examples 1 to 78, Comparative Examples 1 to 26, Comparative Example A and Comparative Example B obtained as described above, white light of 1000 lux was produced immediately after production. The open circuit voltage and IV curve were measured in the irradiated state, and the photoelectric conversion efficiency η1 (%) was calculated from the IV curve. The result of an open circuit voltage is shown to Tables 1-13. The light source, illuminance meter, and power source used for measuring the IV curve are as follows.
Light source: White LED (product name “LEL-SL5N-F”, manufactured by Toshiba Lighting & Technology Corp.)
Illuminance meter: Product name “AS ONE LM-331”, ASONE power supply: Voltage / current generator (Product name “ADVANTEST R6246”, manufactured by Advantest Corporation)

(2) Evaluation of durability About the photoelectric conversion elements of Examples 1 to 78, Comparative Examples 1 to 26, Comparative Examples A, and B obtained as described above, they were placed in an environment of 85 ° C. for 200 hours. Thereafter, the photoelectric conversion efficiency η2 (%) was calculated in the same manner as described above. And the maintenance factor of photoelectric conversion efficiency was computed based on the following formula. The results are shown in Tables 1-13.

Maintenance rate of photoelectric conversion efficiency (%) = 100 × η2 / η1

  From the results shown in Tables 1 to 13, in the photoelectric conversion elements of Examples 1 to 78, both the open-circuit voltage and the maintenance ratio of the photoelectric conversion efficiency were higher than those of Comparative Example A. On the other hand, in Comparative Examples 1-26 and B, the photoelectric conversion efficiency was lower than that in Comparative Example A among the open circuit voltage and the maintenance ratio of the photoelectric conversion efficiency.

  From the above, it was confirmed that according to the electrolyte for a photoelectric conversion element of the present invention, the open-circuit voltage and durability of the photoelectric conversion element can be improved.

DESCRIPTION OF SYMBOLS 10 ... 1st electrode substrate 11 ... Transparent substrate 12 ... Transparent conductive layer 20 ... 2nd electrode substrate 21 ... Conductive substrate 30 ... Oxide semiconductor layer 50 ... Electrolyte 60 ... Photoelectric conversion cell 100 ... Photoelectric conversion element

Claims (7)

A redox couple,
Including base metal oxides,
The electrolyte for photoelectric conversion elements whose density | concentration of the base metal oxide whose density | concentration is the maximum is 1-500 mass ppm (however, except 500 mass ppm) among the said base metal oxides.   The base metal oxide is bismuth oxide, zinc oxide, copper oxide, iron oxide, manganese oxide, lead oxide, tin oxide, nickel oxide, aluminum oxide, tungsten oxide, molybdenum oxide, magnesium oxide, cobalt oxide, cadmium oxide, titanium oxide. And at least one selected from the group consisting of zirconium oxide, antimony oxide, beryllium oxide, chromium oxide, germanium oxide, vanadium oxide, gallium oxide, hafnium oxide, indium oxide, niobium oxide, rhenium oxide, and thallium oxide The electrolyte for photoelectric conversion elements according to claim 1.   The electrolyte for a photoelectric conversion element according to claim 1, wherein the base metal oxide includes at least one selected from the group consisting of at least bismuth oxide, zinc oxide, and tin oxide.   The electrolyte for a photoelectric conversion element according to claim 3, wherein the base metal oxide contains bismuth oxide.   The electrolyte for photoelectric conversion elements according to any one of claims 1 to 4, wherein a concentration of the base metal oxide having a maximum concentration among the base metal oxides is 2 to 100 ppm by mass. Comprising at least one photoelectric conversion cell;
The photoelectric conversion cell is
A first electrode substrate;
A second electrode substrate facing the first electrode substrate;
An oxide semiconductor layer provided on the first electrode substrate or the second electrode substrate;
An electrolyte provided between the first electrode substrate and the second electrode substrate,
The photoelectric conversion element which the said electrolyte consists of the electrolyte for photoelectric conversion elements as described in any one of Claims 1-5. At least one of the first electrode substrate and the second electrode substrate has a glass substrate in contact with the electrolyte;
The photoelectric conversion element according to claim 6, wherein the glass substrate contains a base metal oxide common to the base metal oxide in the electrolyte.

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