JP5480234B2 - Photoelectric conversion element and method for producing photoelectric conversion element - Google Patents

Description

  The present invention relates to a photoelectric conversion element and a method for manufacturing the photoelectric conversion element.

  As an energy source that replaces fossil fuel, a battery that can convert sunlight into electric power, that is, a solar cell, has attracted attention. At present, some solar cells and thin film silicon solar cells using a crystalline silicon substrate are beginning to be put into practical use.

  However, a solar cell using a crystalline silicon substrate has a problem that the manufacturing cost of the silicon substrate is high. In addition, the thin film silicon solar cell has a problem in that the manufacturing cost is high because it is necessary to use many kinds of semiconductor manufacturing gases and complicated devices. For this reason, in any solar cell, efforts have been made to increase the efficiency of photoelectric conversion in order to reduce the cost per power generation output, but the above problem has not yet been solved sufficiently.

  Further, for example, Patent Document 1 (Japanese Patent No. 2664194) discloses a photoelectric conversion element using a photo-induced electron transfer of a metal complex as a new type of solar cell. For example, Patent Document 2 (Japanese Patent Laid-Open No. 2008-287900) discloses a photoelectric conversion element using quantum dots as a new type of solar cell.

  In these photoelectric conversion elements, electrodes are respectively formed on the surfaces of the two substrates, the two substrates are arranged so that these electrodes are inside, and the photoelectric conversion layer and the electrolytic solution are sandwiched between the electrodes. It has been made. The photoelectric conversion layer is composed of a semiconductor layer in which a photosensitizing dye is adsorbed to give an absorption spectrum in the visible light region. Such a photoelectric conversion element is also called a dye-sensitized solar cell.

  When light enters the photoelectric conversion element as described above, electrons are generated in the photoelectric conversion layer, and the electrons generated in the photoelectric conversion layer reach the electrode through the photoelectric conversion layer. Then, the electrons that have reached the electrodes move to the other electrode through an external electric circuit that connects the electrodes, are supplied to the electrolytic solution, are carried by the ions in the electrolytic solution, and return to the photoelectric conversion layer again. In the photoelectric conversion element, electric energy is extracted by such an electron flow.

  In addition, since the basic structure of the photoelectric conversion element as described above is a structure using a substrate (TCO substrate) on which a transparent conductive layer is formed, there is a problem that the cost is high. In order to solve this problem, for example, Patent Document 3 (Japanese Patent No. 4415448) proposes a photoelectric conversion element that does not use a TCO substrate. This photoelectric conversion element is produced by forming a porous semiconductor layer on a translucent substrate instead of using a TCO substrate, and forming a perforated current collecting electrode having a mesh size of 20 to 500 mesh on the porous semiconductor layer. Has been.

However, when the TCO substrate is not used as in the photoelectric conversion element described in Patent Document 3, there is a problem that the short-circuit current density (J _sc ) is lower than that of the photoelectric conversion element having a conventional structure.

Furthermore, in Patent Document 4 (Japanese Patent Laid-Open No. 2007-141473), in order to obtain a large short-circuit current value, the amount of dye adsorbed to the porous semiconductor layer is set to 2.0 × 10 ⁻⁴ mol / cm ³ to A photoelectric conversion element having 3.0 × 10 ⁻⁴ mol / cm ³ is described.

Japanese Patent No. 2664194 JP 2008-287900 A Japanese Patent No. 4415448 JP 2007-141473 A

  However, even the photoelectric conversion element described in Patent Document 4 is not sufficiently reduced in manufacturing cost, and further reduction in manufacturing cost has been demanded.

  In view of the above circumstances, an object of the present invention is to provide a photoelectric conversion element capable of manufacturing a photoelectric conversion element exhibiting a high short-circuit current density at a low cost and a method for manufacturing the photoelectric conversion element.

The present invention includes a translucent substrate, a photoelectric conversion layer provided on a transparent substrate, and a collector electrode provided on at least a part of the photoelectric conversion layer, arranged so as to face the light-transmitting substrate A counter electrode conductive layer, a catalyst layer provided on the surface of the counter electrode conductive layer on the translucent substrate side, and a carrier transport material provided between the translucent substrate and the catalyst layer, and a photoelectric conversion layer is seen containing a porous semiconductor layer made of titanium oxide porous semiconductor layer or silicon oxide is formed consisting of titanium oxide, a ruthenium containing metal complex dye adsorbed to the porous semiconductor layer, the porous semiconductor layer The adsorption amount of the ruthenium-based metal complex is 1.8 × 10 ⁻⁵ mol / cm ³ or more and 5 × 10 ⁻⁵ mol / cm ³ or less.

  Here, it is preferable that the photoelectric conversion element of this invention has an organic compound which has at least one adsorption group which can adsorb | suck to a porous semiconductor layer in a photoelectric converting layer.

  In the photoelectric conversion element of the present invention, the adsorption group is preferably any of a carboxyl group, a hydroxyl group, a sulfo group, or a phosphate group.

  Moreover, it is preferable that the photoelectric conversion element of this invention has an inorganic compound with less adsorption amount of a pigment | dye than a porous semiconductor layer in a photoelectric converting layer.

Further, in the photoelectric conversion element of the present invention, the inorganic compound is preferably at least one member selected from the group consisting of acid aluminum and magnesium oxide.

  Further, the present invention is a method for producing the above photoelectric conversion element, including a step of forming a photoelectric conversion layer by adsorbing a dye to the porous semiconductor layer, and the step of forming the photoelectric conversion layer is porous It is a manufacturing method of the photoelectric conversion element including the process of immersing the quality semiconductor layer in the solution containing an organic compound and a pigment | dye.

  Furthermore, the present invention is a method for producing the above-described photoelectric conversion element, which includes a step of forming a photoelectric conversion layer by adsorbing a dye to the porous semiconductor layer, and the step of forming the photoelectric conversion layer includes a porous layer. And a step of immersing the porous semiconductor layer in the solution containing the organic compound, and a step of immersing the porous semiconductor layer in the solution containing the dye after the step of immersing the porous semiconductor layer in the solution containing the organic compound. It is a manufacturing method.

  ADVANTAGE OF THE INVENTION According to this invention, the photoelectric conversion element which can manufacture the photoelectric conversion element which shows a high short circuit current density at low cost, and the manufacturing method of a photoelectric conversion element can be provided.

It is typical sectional drawing of the photoelectric conversion element of embodiment. It is typical sectional drawing illustrating a part of manufacturing process of an example of the manufacturing method of the photoelectric conversion element of embodiment. It is typical sectional drawing illustrating other one part of the manufacturing process of an example of the manufacturing method of the photoelectric conversion element of embodiment. It is typical sectional drawing illustrating other one part of the manufacturing process of an example of the manufacturing method of the photoelectric conversion element of embodiment. It is typical sectional drawing illustrating other one part of the manufacturing process of an example of the manufacturing method of the photoelectric conversion element of embodiment.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Photoelectric conversion element>
FIG. 1 shows a schematic cross-sectional view of a photoelectric conversion element of the present embodiment which is an example of the photoelectric conversion element of the present invention. The photoelectric conversion element according to the present embodiment includes a translucent substrate 1, a photoelectric conversion layer 2 provided on the translucent substrate 1, and a current collecting electrode 3 provided on at least a part of the photoelectric conversion layer 2. The counter electrode conductive layer 4 provided so as to face the translucent substrate 1, the catalyst layer 8 provided on the surface of the counter electrode conductive layer 4 on the side of the translucent substrate 1, the translucent substrate 1 and the catalyst layer 8 and a carrier transporting material 5 provided between the two.

  Here, the translucent substrate 1 and the counter electrode conductive layer 4 are arranged with a predetermined distance so as to face each other, and the carrier transport material 5 is interposed between the translucent substrate 1 and the counter electrode conductive layer 4. A sealing material 6 for joining the translucent substrate 1 and the counter electrode conductive layer 4 is disposed so as to surround the substrate.

  In addition, the current collecting electrode 3 passes through the upper surface and side surfaces of the photoelectric conversion layer 2 and the surface of the light transmissive substrate 1 so that a current can be taken out of the photoelectric conversion element, and the light transmissive substrate 1 and the sealing material 6. It extends from the space between and outside.

<Translucent substrate>
As the light-transmitting substrate 1, at least a light-transmitting material can be used. However, any material may be used as long as it is a material that substantially transmits light having a wavelength that has an effective sensitivity to at least a dye described later, and is not necessarily transparent to light in all wavelength regions.

  Examples of the light-transmitting material used for the light-transmitting substrate 1 include glass substrates such as soda lime float glass, fused silica glass, and crystal quartz glass, or heat-resistant resin plates such as flexible films. be able to.

  Examples of the flexible film used for the translucent substrate 1 include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PA), and polyether. A film such as imide (PEI), phenoxy resin, or polytetrafluoroethylene (PTFE) can be used.

  As a flexible film used for the translucent substrate 1, it is preferable to use a PTFE film. Since the PTFE film has a heat resistance of 250 ° C. or higher, when the surface of the translucent substrate 1 is heated to, for example, about 250 ° C., thermal damage to the translucent substrate 1 tends to be suppressed.

  Moreover, although the thickness of the translucent board | substrate 1 is not specifically limited, It is preferable that they are 0.2 mm or more and 5 mm or less. When the thickness of the translucent substrate 1 is 0.2 mm or more, the translucent substrate 1 tends to exhibit a function as a support. When the thickness of the translucent substrate 1 is 5 mm or less, the amount of light transmitted through the translucent substrate 1 increases and the short-circuit current density of the photoelectric conversion element tends to increase.

  When attaching the photoelectric conversion element of this Embodiment to another structure, it can attach using the translucent board | substrate 1. FIG. For example, when the translucent substrate 1 is made of a glass substrate, the peripheral portion of the translucent substrate 1 can be easily attached to another structure with screws or the like.

<Photoelectric conversion layer>
As the photoelectric converting layer 2, what contains a porous semiconductor layer and the pigment | dye adsorb | sucked to a porous semiconductor layer can be used. The carrier transport material 5 can move freely inside and outside the photoelectric conversion layer 2.

<Porous semiconductor layer>
The porous semiconductor layer used for the photoelectric conversion layer 2 is not particularly limited as long as it is composed of a porous semiconductor. For example, titanium oxide, zinc oxide, tin oxide, iron oxide, niobium oxide, cerium oxide, At least one selected from the group consisting of tungsten oxide, nickel oxide, strontium titanate, cadmium sulfide, lead sulfide, zinc sulfide, indium phosphide, copper indium sulfide (CuInS ₂ ), CuAlO ₂ and SrCu ₂ O ₂ A layer made of a porous semiconductor can be used. Among these, titanium oxide is preferably used from the viewpoint of improving the stability and safety of the porous semiconductor layer.

  In this specification, “titanium oxide” is not limited to various narrowly defined oxides of titanium, such as anatase-type titanium oxide, rutile-type titanium oxide, amorphous titanium oxide, metatitanic acid, and orthotitanic acid. In addition, it is a concept including a titanium compound containing oxygen such as titanium oxide, titanium hydroxide and hydrous titanium oxide, and these can be used alone or in combination. Titanium oxide can be in any of two types of crystal systems, anatase type and rutile type, depending on the production method and thermal history, but anatase type is common. As the titanium oxide, it is preferable to use an anatase type content of 80% or more.

  As the porous semiconductor layer, for example, a single crystal or a polycrystalline semiconductor can be used. From the viewpoint of improving the stability of the porous semiconductor layer, easiness of crystal growth, and reducing manufacturing costs, the polycrystalline semiconductor layer can be used. The semiconductor is preferably used, and the form of polycrystalline semiconductor fine particles is particularly preferable. Here, the average particle diameter of the semiconductor fine particles is, for example, not less than 1 nm and not more than 1000 μm. In the present specification, “the particle diameter of the semiconductor fine particles” means the maximum diameter of the semiconductor fine particles, and “the average particle diameter of the semiconductor fine particles” means the average value of the particle diameters of the semiconductor fine particles.

  Accordingly, it is particularly preferable to use fine particles of titanium oxide (average particle diameter: 1 nm to 1000 μm) as the porous semiconductor layer. The fine particles of titanium oxide can be produced by a known method such as a gas phase method or a liquid phase method (hydrothermal synthesis method, sulfuric acid method). It can also be produced by high-temperature hydrolysis of chlorides developed by Degussa.

  As the semiconductor fine particles, a mixture of two or more different types of semiconductor fine particles made of the same or different semiconductors may be used. It is considered that semiconductor fine particles having a large particle diameter scatter incident light and contribute to an improvement in the light capture rate, and semiconductor fine particles having a small particle diameter contribute to an improvement in the amount of dye adsorbed by increasing the number of adsorption points. Here, the ratio of the average particle diameter of the semiconductor fine particles having different particle diameters is preferably 10 times or more, and the average particle diameter of the semiconductor fine particles having a large particle diameter is 100 nm to 500 nm, and the semiconductor having a small particle diameter The average particle size of the fine particles is more preferably 5 nm or more and 50 nm or less. In the case of using mixed particles composed of two or more kinds of semiconductor fine particles of different semiconductors, it is effective to make semiconductor fine particles having a stronger dye adsorption action into semiconductor fine particles having a small particle diameter.

  The thickness of the porous semiconductor layer is not particularly limited, but is preferably 1 μm or more and 50 μm or less, and more preferably 5 μm or more and 30 μm or less.

<Dye>
Examples of the dye adsorbed on the porous semiconductor layer include one or two dyes such as an organic dye and / or a metal complex dye that can absorb light having a wavelength in the visible light region and / or the infrared light region. More than one species can be selectively used.

  Examples of organic dyes include azo dyes, quinone dyes, quinone imine dyes, quinacridone dyes, squarylium dyes, cyanine dyes, merocyanine dyes, triphenylmethane dyes, xanthene dyes, porphyrin dyes, and perylenes. At least one selected from the group consisting of a system dye, an indigo dye, and a naphthalocyanine dye can be used. In general, the extinction coefficient of an organic dye is larger than the extinction coefficient of a metal complex dye having a form in which molecules are coordinated to a transition metal.

  As the metal complex dye, one in which a metal is coordinated to a molecule can be used. Here, examples of the molecule include porphyrin dyes, phthalocyanine dyes, naphthalocyanine dyes, ruthenium dyes, and the like. Examples of the metal include Cu, Ni, Fe, Co, V, Sn, Si, Ti, Ge, Cr, Zn, Ru, Mg, Al, Pb, Mn, In, Mo, Y, Zr, Nb, Sb, La, W, Pt, Ta, Ir, Pd, Os, Ga, Tb, Eu, Rb, Bi, Se, As, Sc, Ag, Cd, Hf, Re, Au, Ac, Tc, Te, Rh, etc. It is done. Among these, as the metal complex dye, those in which a metal is coordinated to a phthalocyanine dye or ruthenium dye are preferable, and those in which a metal is coordinated to a ruthenium metal complex dye are particularly preferable.

  As the dye, it is particularly preferable to use ruthenium-based metal complex dyes represented by the following formulas (I) to (III). When a ruthenium-based metal complex dye represented by the following formulas (I) to (III) is used as the dye, light of a wavelength in the near-infrared region can be absorbed. The current density can be increased.

  Examples of commercially available ruthenium-based metal complex dyes include trade name Ruthenium 535 dye, Ruthenium 535-bisTBA dye, Ruthenium 620-1H3TBA dye manufactured by Solaronix. In the following formulas (II) and (III), “TBA” represents tetrabutylammonium.

  In order to firmly adsorb the dye to the porous semiconductor layer, at least selected from the group consisting of a carboxyl group, an alkoxy group, a hydroxyl group, a sulfo group, an ester group, a mercapto group, and a phosphonyl group in the dye molecule. Those having one type of interlocking group are preferred. The interlock group is generally present when the dye is fixed to the porous semiconductor layer, and provides an electrical bond that facilitates the movement of electrons between the excited dye and the semiconductor conduction band. To do.

Further, the photoelectric conversion layer 2 includes a porous semiconductor layer and a dye adsorbed on the porous semiconductor layer, and the amount of the dye adsorbed is 5 × 10 ⁻⁵ mol / cm ³ or less.

As a result of intensive studies by the present inventors, the amount of dye adsorbed on the porous semiconductor layer of the photoelectric conversion layer 2 is set to 5 × 10 ⁻⁵ mol / cm ³ or less, thereby using a TCO substrate. This is because it has been found that a photoelectric conversion element exhibiting a high short-circuit current density can be produced even if it is not necessary, and that the amount of dye adsorbed can be reduced as compared with the conventional case, so that the photoelectric conversion element can be produced at low cost. .

The adsorption amount of the dye adsorbed on the porous semiconductor layer of the photoelectric conversion layer 2 is preferably 3 × 10 ⁻⁵ mol / cm ³ or less, and is 2.2 × 10 ⁻⁵ mol / cm ³ or less. Is more preferable. When the amount of dye adsorbed is 3 × 10 ⁻⁵ mol / cm ³ or less, particularly 2.2 × 10 ⁻⁵ mol / cm ³ or less, the short-circuit current density of the photoelectric conversion element should be further increased. In addition, the photoelectric conversion element can be manufactured at a lower cost.

The amount of dye adsorbed on the porous semiconductor layer of the photoelectric conversion layer 2 is preferably 1 × 10 ⁻⁵ mol / cm ³ or more, and is 1.8 × 10 ⁻⁵ mol / cm ³ or more. Is more preferably 2.1 × 10 ⁻⁵ mol / cm ³ or more. When the amount of dye adsorbed is 1 × 10 ⁻⁵ mol / cm ³ or more, and further 1.8 × 10 ⁻⁵ mol / cm ³ or more, particularly 2.1 × 10 ⁻⁵ mol / cm ³ or more. In this case, the amount of the dye adsorbed on the porous semiconductor layer does not decrease too much, and the short-circuit current density of the photoelectric conversion element tends to be increased.

<Inorganic compounds>
It is preferable that the photoelectric conversion layer 2 contains an inorganic compound that absorbs less dye than the porous semiconductor layer. In this case, there is a tendency that the amount of dye adsorbed can be reduced while maintaining a high short-circuit current density.

  Here, the inorganic compound is preferably at least one selected from the group consisting of silicon oxide, aluminum oxide, and magnesium oxide. In this case, the tendency to reduce the amount of dye adsorbed while maintaining a high short-circuit current density is further increased.

  The inorganic compound can be provided in the porous semiconductor layer, for example, by applying a solution containing the inorganic compound to the porous semiconductor layer and then performing at least one of drying and baking.

<Organic compounds>
It is preferable that the photoelectric conversion layer 2 includes an organic compound having at least one adsorbing group that can be adsorbed to the porous semiconductor layer. The organic compound is preferably adsorbed to the porous semiconductor layer simultaneously with the dye adsorption or before the dye adsorption in order to reduce the amount of the dye adsorbed to the porous semiconductor layer.

  As the organic compound, it is preferable to use an organic compound containing at least one adsorption group for adsorbing to the porous semiconductor layer and at least one inhibition group for inhibiting the adsorption of the dye. Any adsorbing group may be used as long as it can be adsorbed on the porous semiconductor layer, and among them, any of a carboxyl group, a hydroxyl group, a sulfo group, and a phosphoric acid group is preferable.

  In addition, the inhibiting group for inhibiting the adsorption of the dye may be any group having an effect of inhibiting the adsorption of the dye, and among them, a linear alkyl group, a branched alkyl group, other cyclic compounds, or a cyclic structure may be used. Examples include organic structures.

<Collector electrode>
As the current collecting electrode 3, indium tin composite oxide (ITO), tin oxide (SnO ₂ ), tin oxide doped with fluorine (FTO), zinc oxide (ZnO), titanium, nickel, tantalum, or the like is used. be able to.

  The thickness of the current collecting electrode 3 is preferably 0.02 μm or more and 5 μm or less, and the electric resistance of the current collecting electrode 3 is preferably as low as possible, more preferably 40Ω / □.

  The current collecting electrode 3 is preferably provided with a small hole. When the collecting electrode 3 is provided with a small hole, when the collecting electrode 3 is formed, when the electrode is immersed in a solution containing a dye or infiltrated with an electrolyte, the solution containing the dye or the electrolyte Therefore, the short circuit current density of the photoelectric conversion element tends to be increased.

  The small holes of the current collecting electrode 3 can be formed by, for example, a mechanical method or laser processing. Here, the small hole of the current collecting electrode 3 is preferably an opening having a diameter of 0.1 μm or more and 100 μm or less, and more preferably an opening of 1 μm or more and 50 μm or less. The interval between adjacent small holes is preferably 1 μm or more and 200 μm or less, and more preferably 10 μm or more and 300 μm or less.

<Carrier transport material>
As the carrier transport material 5, a conductive material capable of transporting ions can be used. For example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, a molten salt gel electrolyte, or the like can be used. The carrier transport material 5 is present in a form that fills the voids of the structure formed between the translucent substrate 1 and the counter electrode conductive layer 4.

  The liquid electrolyte is not particularly limited as long as it is a liquid substance containing a redox species, and can be generally used in a battery, a solar battery, or the like. Examples of the liquid electrolyte include those comprising a redox species and a solvent capable of dissolving the same, those comprising a redox species and a molten salt capable of dissolving the same, or a redox species and a solvent and molten salt capable of dissolving the same. The thing which consists of can be used.

Examples of the redox species include I ⁻ / I ³⁻ series, Br ²⁻ / Br ³⁻ series, Fe 2 ⁺ / Fe ³⁺ series, and quinone / hydroquinone series. As the redox species, among others, combinations of metal iodides such as lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), calcium iodide (CaI ₂ ) and iodine (I ₂ ) Tetraalkylammonium iodide (TEAI), Tetrapropylammonium iodide (TPAI), Tetrabutylammonium iodide (TBAI), Tetrahexylammonium iodide (THAI) and other combinations of tetraalkylammonium salts and iodine, and lithium bromide A combination of a metal bromide such as (LiBr), sodium bromide (NaBr), potassium bromide (KBr), calcium bromide (CaBr ₂ ) and bromine is preferable, and among these, a combination of LiI and I ₂ is particularly preferable.

  Examples of the redox species solvent include carbonate compounds such as propylene carbonate, nitrile compounds such as acetonitrile, alcohols such as ethanol, water, and aprotic polar substances. Among these, carbonate compounds and nitrile compounds are particularly preferable. Two or more of these solvents can be used in combination.

  The solid electrolyte is a conductive material that can transport electrons, holes, and ions, and can be used as an electrolyte of a solar cell and has no fluidity. Examples of the solid electrolyte include a hole transport material such as polycarbazole, an electron transport material such as tetranitrofluororenone, a conductive polymer such as polyroll, a polymer electrolyte obtained by solidifying a liquid electrolyte with a polymer compound, and copper iodide. A p-type semiconductor such as copper thiocyanate, or an electrolyte obtained by solidifying a liquid electrolyte containing a molten salt with fine particles can be used.

  The gel electrolyte is usually composed of an electrolyte and a gelling agent. Examples of gelling agents include polymer gelation such as crosslinked polyacrylic resin derivatives, crosslinked polyacrylonitrile derivatives, polyalkylene oxide derivatives, silicone resins, and polymers having a nitrogen-containing heterocyclic quaternary compound salt structure in the side chain. An agent or the like can be used.

  The molten salt gel electrolyte is usually composed of the gel electrolyte as described above and a room temperature molten salt. Examples of the room temperature molten salt include nitrogen-containing heterocyclic quaternary ammonium salt compounds such as pyridinium salts and imidazolium salts.

  You may add an additive to said electrolyte as needed. Additives include nitrogen-containing aromatic compounds such as t-butylpyridine (TBP), or dimethylpropylimidazole iodide (DMPII), methylpropylimidazole iodide (MPII), ethylmethylimidazole iodide (EMII), ethylimidazole An imidazole salt such as iodide (EII) or hexylmethylimidazole iodide (HMII) can be used.

  The electrolyte concentration in the electrolyte is preferably 0.001 mol / L or more and 1.5 mol / L or less, and more preferably 0.01 mol / L or more and 0.7 mol / L or less.

<Counter electrode conductive layer>
As the counter electrode conductive layer 4, a conductive material can be used, which may or may not have optical transparency. However, in the case where the counter electrode conductive layer 4 side is the light receiving side, it is necessary to have the same light transmissivity as the above-described translucent substrate.

Examples of the material constituting the counter electrode conductive layer 4 include indium tin composite oxide (ITO), tin oxide (SnO ₂ ), tin oxide doped with fluorine (FTO), and zinc oxide (ZnO). It is done. Moreover, you may use the metal which does not show corrosivity with respect to the carrier transport material 5, such as titanium, nickel, or tantalum.

  The thickness of the counter electrode conductive layer 4 is preferably 0.02 μm or more and 5 μm or less, and the electric resistance of the counter electrode conductive layer 4 is more preferably 40Ω / □ or less. In order to facilitate injection of the carrier transport material 5, it is preferable to form a plurality of small holes for injection of the carrier transport material 5 in the counter electrode conductive layer 4.

  The small holes of the counter electrode conductive layer 4 can be formed by, for example, a mechanical technique or laser processing. Here, the small hole of the counter electrode conductive layer 4 is preferably an opening having a diameter of 0.1 μm or more and 100 μm or less, and more preferably an opening of 1 μm or more and 50 μm or less. The interval between adjacent small holes is preferably 1 μm or more and 300 μm or less, and more preferably 10 μm or more and 200 μm or less. The same effect can be obtained by forming a stripe-shaped opening in the counter electrode conductive layer 4. The interval between the stripe-shaped openings formed in the counter electrode conductive layer 4 is preferably 1 μm or more and 300 μm or less, and more preferably 10 μm or more and 200 μm or less.

<Catalyst layer>
The catalyst layer 8 may be any material that can transfer electrons on the surface of the catalyst layer 8. For example, a noble metal material such as platinum or palladium, or a carbon-based material such as carbon black, ketjen black, carbon nanotube, or fullerene. Etc. can be used.

<Encapsulant>
As the sealing material 6, for example, a single layer including at least one selected from the group consisting of a silicone resin, an epoxy resin, a polyisobutylene resin, a hot melt resin, and a glass frit, or the single layer is made into two or more layers. A plurality of stacked layers can be used. Specifically, a model number manufactured by ThreeBond: 31X-101, a model number manufactured by ThreeBond: 31X-088, or a commercially available epoxy resin can be used. .

  When a silicone resin, an epoxy resin, or a glass frit is used as the sealing material 6, it can be formed using a dispenser. Moreover, when using hot-melt resin as the sealing material 6, it can form by opening the hole patterned in the sheet-like hot-melt resin. Moreover, the material for sealing the hole for injection | pouring of the carrier transport material 5 formed in the counter electrode conductive layer 4 can also be formed using said material.

<Manufacturing method>
Hereinafter, an example of the method for manufacturing the photoelectric conversion element of the present embodiment will be described with reference to the schematic cross-sectional views of FIGS.

  First, as shown in FIG. 2, a step of preparing a translucent substrate 1 is performed. The process of preparing the translucent board | substrate 1 can be performed by preparing what is marketed, for example.

  Next, as shown in FIG. 3, a step of forming a porous semiconductor layer 2a on the surface of the translucent substrate 1 is performed. Here, the step of forming the porous semiconductor layer 2a is not particularly limited. For example, a suspension containing the above-described semiconductor fine particles is applied onto the surface of the light-transmitting substrate 1, and at least one of drying and baking is performed. It can be done by the method of doing.

  Specifically, first, the semiconductor fine particles are suspended in an appropriate solvent to obtain a suspension. As such a solvent, a glyme solvent such as ethylene glycol monomethyl ether, an alcohol such as isopropyl alcohol, an alcohol mixed solvent such as a mixed solvent of isopropyl alcohol and toluene, or water can be used. Further, instead of such a suspension, a commercially available titanium oxide paste (for example, Solaronix, Ti-nanoxide, T, D, T / SP, D / SP, R / SP) may be used.

  Next, the suspension obtained as described above is applied onto the surface of the light-transmitting substrate 1, and at least one of drying and baking is performed to form the porous semiconductor layer 2a on the surface of the light-transmitting substrate 1. Form.

  As a method for applying the suspension, for example, a known method such as a doctor blade method, a squeegee method, a spin coating method, or a screen printing method can be used.

  What is necessary is just to set suitably temperature, time, atmosphere, etc. which are required for drying and baking according to the kind of semiconductor fine particle, for example, at the temperature of 50 degreeC or more and 800 degrees C or less in air | atmosphere atmosphere or inert gas atmosphere. It can be performed for 10 seconds to 12 hours. This drying and baking may be performed once at a single temperature or twice or more at different temperatures.

  In the case of forming a plurality of porous semiconductor layers 2a, the steps of preparing suspensions of different semiconductor fine particles and performing at least one of coating, drying and firing may be repeated twice or more.

  In addition, after the formation of the porous semiconductor layer 2a, post-processing is performed for the purpose of improving the performance such as improvement of electrical connection between the semiconductor fine particles, increase of the surface area of the porous semiconductor layer 2a, and reduction of defect levels of the semiconductor fine particles. May be performed. For example, when the porous semiconductor layer 2a is a titanium oxide film, the performance of the porous semiconductor layer 2a can be improved by treating with a titanium tetrachloride aqueous solution.

  Then, as shown in FIG. 3, the process of forming the current collection electrode 3 in at least one part of the porous semiconductor layer 2a is performed. Here, the process of forming the current collection electrode 3 can be performed by well-known methods, such as a sputtering method, a spray method, a vapor deposition method, or screen printing, for example.

  Next, as shown in FIG. 4, the process of forming the photoelectric converting layer 2 is performed by making a pigment | dye adsorb | suck to the porous semiconductor layer 2a. Here, examples of the method for adsorbing the dye on the porous semiconductor layer 2a include a method of immersing the porous semiconductor layer 2a in a solution in which the dye is dissolved (dye adsorption solution). At this time, the dye adsorbing solution may be heated in order to penetrate the dye adsorbing solution to the depths of the fine holes in the porous semiconductor layer 2a.

The solvent that dissolves the dye may be any solvent that dissolves the dye, and examples thereof include alcohol, toluene, acetonitrile, tetrahydrofuran (THF), chloroform, and dimethylformamide. These solvents are preferably purified and may be used in combination of two or more. The dye concentration in the dye adsorption solution can be appropriately set according to the conditions such as the dye to be used, the type of the solvent, the dye adsorption step, and the like, but is preferably 1 × 10 ⁻⁵ mol / L or more, for example. .

  Conditions such as the temperature, immersion time, and atmosphere of the dye adsorption solution during adsorption of the dye to the porous semiconductor layer 2a are appropriately determined depending on the material and state of the porous semiconductor layer 2a, the component material of the dye adsorption solution, and the like. You can set it. The immersion of the porous semiconductor layer 2a in the dye adsorbing solution can be performed, for example, at about room temperature in an air atmosphere. However, the porous semiconductor layer 2a is porous by being immersed under heating (at a temperature of 30 ° C. or more and 60 ° C. or less). The dye can be efficiently adsorbed to the semiconductor layer 2a.

  The adsorption of the dye to the porous semiconductor layer 2a may be performed before or after the current collector electrode 3 is formed, but is preferably performed after the current collector electrode 3 is formed.

  In the case where an organic compound containing at least one adsorption group for adsorbing to the porous semiconductor layer 2a and at least one inhibition group for inhibiting the adsorption of the dye is adsorbed on the porous semiconductor layer 2a. From the viewpoint of suppressing the amount of dye adsorbed on the porous semiconductor layer 2a, it is preferable to carry out the method by any one of the following methods (i) and (ii).

  (I) The translucent substrate 1 on which the porous semiconductor layer 2a is formed is immersed in a solution containing the organic compound and the dye.

  (Ii) After immersing the translucent substrate 1 on which the porous semiconductor layer 2a is formed in a solution containing the organic compound, the translucent substrate 1 on which the porous semiconductor layer 2a is formed contains a dye. It is immersed in a solution (dye adsorption solution).

As described above, the amount of dye adsorbed on the porous semiconductor layer 2a is 5 × 10 ⁻⁵ mol / cm ³ or less, preferably 3 × 10 ⁻⁵ mol / cm ³ or less, more preferably 2.2. × 10 ⁻⁵ mol / cm ³ or less.

Further, as described above, the adsorption amount of the dye to the porous semiconductor layer 2a is preferably 1.8 × 10 ⁻⁵ mol / cm ³ or more, more preferably 2.1 × 10 ⁻⁵ mol / cm. ³ or more, more preferably 2.1 × 10 ⁻⁵ mol / cm ³ or more.

  Next, as shown in FIG. 5, after forming the catalyst layer 8 on the counter electrode conductive layer 4, the surface of the counter electrode conductive layer 4 and the surface of the translucent substrate 1 are faced to each other. It seals with the sealing material 6 so that the outer periphery may be surrounded, and the counter electrode conductive layer 4 and the translucent substrate 1 are joined with the sealing material 6.

  Thereafter, as shown in FIG. 1, a step of placing a carrier transport material 5 in a region between the translucent substrate 1 and the counter electrode conductive layer 4 is performed. The step of installing the carrier transporting material 5 is performed by, for example, injecting the carrier transporting material 5 into a region surrounded by the sealing material 6 from the hole provided in the counter electrode conductive layer 4 and then closing the hole. The photoelectric conversion element of embodiment shown to can be produced.

<Action and effect>
As described above, in the photoelectric conversion element of the present embodiment, the adsorption amount of the dye to the porous semiconductor layer 2a is 5 × 10 ⁻⁵ mol / cm ³ or less, and therefore, the TCO substrate is not used. In addition, it can be manufactured at a low cost by suppressing the adsorption amount of the dye, and can be a photoelectric conversion element exhibiting a high short-circuit current density.

  Examples The present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In each example, the film thickness of each layer was measured using a product name: Surfcom 1400A manufactured by Tokyo Seimitsu Co., Ltd. unless otherwise specified.

<Example 1>
First, a porous semiconductor layer was formed on the surface of a translucent substrate made of glass (width 20 mm × length 20 mm × thickness 1 mm, manufactured by Matsunami Glass Industrial Co., Ltd.) by the following method.

  A commercially available titanium oxide paste (Solaronix) on a translucent substrate using a screen plate having a pattern of width 10 mm × length 10 mm and a screen printing machine (manufactured by Neurong Precision Industry Co., Ltd., model number: LS-150). (Trade name: Ti-Nanoxide T / SP) was applied, pre-dried at 80 ° C. for 30 minutes, and then fired in air at 500 ° C. for 30 minutes. Further, by repeating the same process, a porous film made of a titanium oxide film having a thickness of 11 μm was formed. Furthermore, a porous film made of a titanium oxide film having a thickness of 3 μm was formed by a commercially available titanium oxide paste (manufactured by Solaronix, trade name: Ti-Nanoxide R / SP) in the same manner as described above, and the total thickness was 14 μm. A porous semiconductor layer made of two titanium oxide films was prepared.

  Next, a current collecting electrode was formed by vapor-depositing a Ti film on the surface of the porous semiconductor layer and the surface of the translucent substrate around the porous semiconductor layer.

Thereafter, the porous semiconductor layer is immersed in a dye adsorbing solution prepared in advance at room temperature for 100 hours and dried at about 60 ° C. for about 5 minutes to adsorb the dye to the porous semiconductor layer. A conversion layer was formed. The adsorption amount of the dye to the porous semiconductor layer at this time was 2.1 × 10 ⁻⁵ mol / cm ³ . Note that the amount of dye adsorbed is the absorbance of the solution from which the dye was eluted by immersing the porous semiconductor layer on which the dye was adsorbed in a solution in which the dye could be dissolved to remove the dye from the porous semiconductor layer. The measurement was performed by calculating the substance amount of the dye eluted in the solution from the calibration curve prepared in advance and the volume of the solution.

The dye adsorbing solution contains a dye represented by the above formula (II) (manufactured by Solaronix, trade name: Ruthenium 620 1H3TBA) at a concentration of 3 × 10 ⁻⁴ mol / L, and deoxycholic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) at a concentration of 6 It was prepared by dissolving in a mixed solvent of acetonitrile and t-butanol having a volume ratio of 1: 1 so as to be × 10 ⁻² mol / L.

  Next, a translucent substrate having a photoelectric conversion layer and a collecting electrode formed thereon, and a counter electrode substrate having a platinum film (film thickness: 1 μm) as a catalyst layer on an ITO conductive film as a counter electrode conductive layer, Bonding using a heat-sealing film (DuPont, Himiran 1702), heating for 10 minutes in an oven set at about 100 ° C., pressure-bonding the translucent substrate and the counter electrode substrate, and surrounding a predetermined area An encapsulant was formed.

  Next, an electrolyte prepared in advance is injected into a region surrounded by the sealing material from an electrolyte injection hole provided in advance in the counter electrode substrate, and an ultraviolet curable resin (manufactured by ThreeBond, model number: 31X-101) was used to seal the electrolyte injection hole. This produced the photoelectric conversion element of Example 1.

In the above electrolyte solution, acetonitrile as a solvent has a concentration of 0.1 mol / L of LiI (manufactured by Aldrich) as a redox species and a concentration of 0.01 mol / L of I ₂ (manufactured by Kishida Chemical). In addition, t-butylpyridine (manufactured by Aldrich) was added as an additive so that the concentration was 0.5 mol / L, and dimethylpropylimidazole iodide (manufactured by Shikoku Kasei Kogyo Co., Ltd.) was added at a concentration of 0.6 mol / L. Obtained by dissolution.

Thereafter, Ag paste (made by Fujikura Kasei Co., Ltd., trade name: Dotite) was applied to the photoelectric conversion element of Example 1 as a terminal electrode portion. Then, a black mask having an opening area of 1 cm ² is installed on the light receiving surface of the photoelectric conversion element of Example 1, and irradiated with light of 1 kW / m ² intensity (AM1.5 solar simulator), Short-circuit current density J _sc (mA / cm ² ), open circuit voltage V _oc (V), FF, and conversion efficiency E _ff (%) were measured. The results are shown in Table 1.

<Example 2>
Except for the following points, the photoelectric conversion element of Example 2 (dye adsorption amount: 1.8 × 10 ⁻⁵ mol / cm ³ ) was produced in the same manner as in Example 1, and the short-circuit current density J _sc and the open circuit voltage V _oc , FF, and conversion efficiency _Eff were measured. The results are shown in Table 1.

That is, the translucent substrate on which the porous semiconductor layer was formed was placed on a hot plate heated to 120 ° C., and after 3 minutes, 5 μl of a 4 mass% ethanol solution of tetraethoxysilane (manufactured by Kishida Chemical Co., Ltd.) 1 ml per 1 cm ³ of porous semiconductor layer) is applied from above the porous semiconductor layer, dried, and then baked at 400 ° C. for 30 minutes, so that the porous semiconductor layer has a smaller amount of dye adsorption than the porous semiconductor layer. _An inorganic compound consisting of ₂ was formed, and then immersed in a dye adsorption solution.

<Example 3>
The photoelectric conversion element of Example 3 (dye adsorption amount: 5 × 10 ^{−5) in the same} manner as in Example 1 except that the concentration of deoxycholic acid in the dye adsorption solution was 4.5 × 10 ⁻² mol / L. mol / cm ³ ) and short circuit current density J _sc , open circuit voltage V _oc , FF, and conversion efficiency E _ff were measured. The results are shown in Table 1.

<Example 4>
The photoelectric conversion element of Example 4 (dye adsorption amount: 3 × 10 ^{−5) in the same} manner as in Example 1 except that the deoxycholic acid concentration of the dye adsorption solution was 5.5 × 10 ⁻² mol / L. mol / cm ³ ) and short circuit current density J _sc , open circuit voltage V _oc , FF, and conversion efficiency E _ff were measured. The results are shown in Table 1.

<Example 5>
The photoelectric conversion element of Example 5 was carried out in the same manner as in Example 1 except that the film thickness of the film formed from a commercially available titanium oxide paste (manufactured by Solaronix, trade name: Ti-Nanoxide T / SP) was 15 μm. (Dye adsorption amount: 2.2 × 10 ⁻⁵ mol / cm ³ ) was prepared, and short-circuit current density J _sc , open-circuit voltage V _oc , FF, and conversion efficiency E _ff were measured. The results are shown in Table 1.

<Example 6>
Except for the following points, the photoelectric conversion element of Example 2 (dye adsorption amount: 1.9 × 10 ⁻⁵ mol / cm ³ ) was produced in the same manner as in Example 1, and the short-circuit current density J _sc and the open-circuit voltage V _oc , FF, and conversion efficiency _Eff were measured. The results are shown in Table 1.

That is, the translucent substrate on which the porous semiconductor layer is formed is dissolved in a mixed solvent of acetonitrile and t-butanol having a volume ratio of 1: 1 so that the concentration of deoxycholic acid is 4 × 10 ⁻² mol / L. After being immersed in the treated solution at room temperature for 2 hours, it was immersed in a dye adsorption solution having a deoxycholic acid concentration of 3 × 10 ⁻² mol / L.

<Comparative Example 1>
The photoelectric conversion element of Example 3 (dye adsorption amount: 7.1 × 10) in the same manner as in Example 1 except that the deoxycholic acid concentration of the dye adsorption solution was 4.5 × 10 ⁻² mol / L. ⁻⁵ mol / cm ³ ), and short-circuit current density J _sc , open-circuit voltage V _oc , FF, and conversion efficiency E _ff were measured. The results are shown in Table 1.

<Comparative example 2>
A photoelectric conversion element (dye adsorption amount: 1 × 10 ⁻⁴ mol / cm ³ ) of Comparative Example 2 was prepared in the same manner as in Example 1 except that deoxycholic acid was not added to the dye adsorption solution. Short-circuit current density J _sc , open circuit voltage V _oc , FF, and conversion efficiency E _ff were measured. The results are shown in Table 1.

As shown in Table 1, in the photoelectric conversion elements of Examples 1 to 6 in which the adsorption amount of the dye to the porous semiconductor layer is 5 × 10 ⁻⁵ mol / cm ³ or less, the photoelectric conversions of Comparative Examples 1 and 2 It was confirmed that the short-circuit current density J _sc was exhibited even though the amount of dye adsorbed was small compared to the device.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The photoelectric conversion element of this invention can be widely utilized for the photoelectric conversion element containing a solar cell, and can be used suitably especially for a dye-sensitized solar cell.

  DESCRIPTION OF SYMBOLS 1 Translucent board | substrate, 2 Photoelectric conversion layer, 2a Porous semiconductor layer, 3 Current collection electrode, 4 Counter electrode conductive layer, 5 Carrier transport material, 6 Sealing material, 8 Catalyst layer.

Claims (7)

A translucent substrate;
A photoelectric conversion layer provided on the translucent substrate;
A collecting electrode provided on at least a part of the photoelectric conversion layer;
A counter electrode conductive layer provided to face the translucent substrate;
A catalyst layer provided on the surface of the counter electrode conductive layer on the light transmitting substrate side;
A carrier transport material provided between the translucent substrate and the catalyst layer,
The photoelectric conversion layer, viewed contains a porous semiconductor layer made of titanium oxide porous semiconductor layer or silicon oxide is formed of an oxide of titanium, and said adsorbed on the porous semiconductor layer ruthenium containing metal complex dye,
The adsorption amount of the ruthenium-based metal complex dye of the porous semiconductor layer is 1.8 × 10 ^-5 mol / cm ³ or more 5 × 10 ^-5 mol / cm ³ or less, the photoelectric conversion element.   The photoelectric conversion element according to claim 1, wherein the photoelectric conversion layer includes an organic compound having at least one adsorbing group that can be adsorbed to the porous semiconductor layer.   The photoelectric conversion element according to claim 2, wherein the adsorption group is any one of a carboxyl group, a hydroxyl group, a sulfo group, and a phosphate group.   4. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion layer contains an inorganic compound that absorbs less of the dye than the porous semiconductor layer. 5. Wherein the inorganic compound is an acid aluminum, and at least one selected from the group consisting of magnesium oxide, the photoelectric conversion element according to claim 4. A method for producing the photoelectric conversion device according to claim 2, wherein
Including the step of forming the photoelectric conversion layer by adsorbing the dye to the porous semiconductor layer,
The step of forming the photoelectric conversion layer includes a step of immersing the porous semiconductor layer in a solution containing the organic compound and the dye. A method for producing the photoelectric conversion device according to claim 2, wherein
Including the step of forming the photoelectric conversion layer by adsorbing the dye to the porous semiconductor layer,
The step of forming the photoelectric conversion layer includes immersing the porous semiconductor layer in a solution containing the organic compound,
A step of immersing the porous semiconductor layer in a solution containing the dye after the step of immersing in the solution containing the organic compound.

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