JP2006128204A - Photoelectric conversion device and optical power generating apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion device excellent in conversion efficiency. <P>SOLUTION: The photoelectric conversion device is provided with a light exciting body 4 formed of particle mainly constituted with sulfuric indium copper for photoelectric conversion, a porous electron transporting body 3 adhered at the front surface with the light exciting body 4 for transporting electrons generated through photoelectric conversion at the light exciting body 4, and a hole transporting body 7 for transporting holes generated through photoelectric conversion at the light exciting body 4. Since the light exciting body 4 is constituted with the particle mainly constituted with sulfuric indium copper, a large amount of light is absorbed by the light exciting body 4 and the carrier generated can be implanted in higher efficiency to the porous electron transporting body 3. Therefore, a highly efficient photoelectric conversion device is manufactured with harmless material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photoelectric conversion device that can be suitably used for a solar cell, a photosensor, a hydrogen generation device based on a photoelectric conversion principle, and a photovoltaic device using the photoelectric conversion device.

  A dye-sensitized solar cell is a mainstream of low-cost solar cells, which are photoelectric conversion devices that have been actively developed in recent years. The dye-sensitized solar cell, which was announced earlier, carries a ruthenium complex sensitizing dye as a photoexciter on a titanium oxide porous body as an electron transporter, and has different constituent parts for excitation and transport of carriers. Is classified into the type of solar cell operated (see, for example, Patent Document 1).

  This type of solar cell is inexpensive to use, can be used without purifying the material used with high purity, uses almost no vacuum equipment in the manufacturing process, is a low-temperature process, is manufactured Its feature is its low cost.

  On the other hand, examples of the metal complex dye used in the dye-sensitized solar cell include thiocyanate ion, 1,10-phenanthroline, 1,10-phenanthroline derivative, and 2,2′-bipyridyl having a coordination center of ruthenium. Also known are isothiocyanate complexes, thiocyanate complexes, porphyrin-based dyes, phthalocyanine-based dyes and the like having 2,2′-bipyridyl derivatives and the like as ligands. In addition to metal complex dyes, organic dyes may also be used. Such organic dyes include xanthene dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine. System dyes and the like are known.

In addition, attempts have been made to use inorganic semiconductor nanoparticles as a dye serving as a photoexciter. For example, CdS, PbS, Ag ₂ S, Sb ₂ S ₃ , Bi ₂ S _3, etc. are used as inorganic semiconductor nanoparticles, and a photoelectric conversion device for supporting these inorganic semiconductor nanoparticles on a titanium oxide porous semiconductor has been studied. (For example, see Non-Patent Documents 1 and 2.)

Furthermore, as a dye-sensitized solar cell, a porous semiconductor layer that functions as an electron transporter, and an inorganic layer that functions as a photoexciter or hole transporter, as an organic substance layer as an organic substance as a sensitizing dye that generates electrons or holes by external light irradiation There is an example in which copper indium sulfide (CuInS ₂ ) or the like is used for an inorganic semiconductor in a structure interposed between semiconductor layers (see, for example, Patent Documents 2 and 3).
U.S. Pat.No. 4,927,721 Ralf Vogel et al., “Sensitization of highly porous TiO2 electrodes by quantum sized CdS”, “Sensitization of highly porous TiO2 electrodes by quantum sized CdS”, (Germany), Vol. 174, CHEMICAL PHYSICS LETTERS, 1990, p. 241-246 Ralf Vogel et al., “Quantum-sized PbS, CdS, Ag2S, Sb2S and Bi2S3, Particles as Sensitizers for Velias, Nanoporous, Wide Bandgap Semiconductors (Quantum- sized PbS, CdS, Ag2S, Sb2S, and Bi2S3 Particles as Sensitizers for Various Nanoporous Wide-Bandgap Semiconductors ”(Germany), Vol. 98, Journal of Physical Chemistry, 1994, p. 3183-3188 US Pat. No. 6,665,701 JP 2001-156321 A

  However, in the dye-sensitized solar cell as described above, since an organic dye is used as a photoexciter, active oxygen species (for example, hydroxy radical, singlet oxygen) generated in an electrolyte or a porous semiconductor during light irradiation are used. , Atomic oxygen, ozone, superoxide anion, peroxide anion, oxygen anion, etc.), or the dye itself is photodegraded by absorption of ultraviolet light.

  For this reason, the dye-sensitized solar cell has a great concern about the weather resistance, and is inferior in terms of reliability as compared with the solar cell using bulk Si which is currently mainstream.

  On the other hand, when inorganic semiconductor nanoparticles are used for the photoexciter with the same structure as that of the dye-sensitized solar cell, the durability is improved as compared with the metal complex dye or the organic dye, but the known inorganic Semiconductor materials have the problem of low conversion efficiency.

  Further, in the case where an organic substance layer is interposed between an inorganic semiconductor layer functioning as a photoexciter and a porous semiconductor layer functioning as an electron transporter, the organic substance layer is altered by active oxygen species or ultraviolet rays in the same manner as described above. Therefore, there is a problem that it is difficult to maintain stable characteristics.

  The present invention has been made in view of the above-mentioned problems, and its object is to have a particularly long-term reliability that can be suitably used for solar cells, photosensors, etc., in the same configuration as a dye-sensitized solar cell. An object of the present invention is to provide a photoelectric conversion device having an excellent conversion efficiency using an inorganic semiconductor material as a photoexciter.

  The photoelectric conversion device of the present invention transports electrons generated by photoelectric conversion by the photoexcited body, which is composed of particles mainly composed of indium copper sulfide and performs photoelectric conversion, and a large number of the photoexcited bodies adhere to the surface. And a hole transporter that transports holes generated by photoelectric conversion in the photoexciter.

  Moreover, the photoelectric conversion device of the present invention is characterized in that, in the above structure, the photoexciter has an average particle diameter of 20 nm or less.

  Moreover, the photoelectric conversion device of the present invention is characterized in that, in each of the above structures, the photoexciter is formed on the surface of the porous electron transporter by a liquid phase method.

  Furthermore, the photoelectric conversion device of the present invention is characterized in that, in each of the above-described configurations, the porous electron transporter has titanium dioxide as a main component.

  The photoelectric conversion device of the present invention is characterized in that any one of the above-described photoelectric conversion devices of the present invention is used as a power generation means, and the generated power of the power generation means is supplied to a load. .

According to the photoelectric conversion device of the present invention, a particulate photoexciter that performs photoelectric conversion, a porous electron transporter that transports electrons generated by photoelectric conversion in the photoexciter, in which a large number of the photoexciters adhere to the surface, A photoelectric conversion device comprising a hole transporter that transports holes generated by photoelectric conversion in a photoexciter, wherein the photoexciter comprises particles containing indium copper sulfide (CuInS ₂ ) as a main component. As a result, compared with the conventional one using other inorganic semiconductors as the photoexciter, the electron conduction level of the photoexciter and the electron conduction level of the porous electron transporter represented by titanium dioxide The offset is an energy difference suitable for electron injection into the porous electron transporter, so that electrons and holes generated by photoelectric conversion are injected from the photoexciter into the porous electron transporter and hole transporter. It can be increased, thereby improving the conversion efficiency. In addition, indium copper sulfide (CuInS ₂ ) serving as a photoexciter is stable with respect to thermal energy or light energy corresponding to sunlight, so that it is not altered by active oxygen species or ultraviolet rays, so that stable characteristics can be maintained. Excellent long-term reliability.

  In addition, according to the photoelectric conversion device of the present invention, when the average particle size of the photoexciter is 20 nm or less, it becomes possible to absorb shorter wavelength light than the bulk state due to the quantum size effect. The carrier density generated in the photoexciter increases, and a high short-circuit current value can be obtained.

  Further, according to the photoelectric conversion device of the present invention, when the photoexciter is formed on the surface of the porous electron transporter by a liquid phase method, the precursor of the photoexciter efficiently penetrates into the porous electron transporter. Then, since the photoexciter is formed inside the porous body, the coverage of the photoexcited body on the porous electron transporter is improved, and a high short-circuit current value can be obtained.

Further, according to the photoelectric conversion device of the present invention, when the porous electron transporter is mainly composed of titanium dioxide, the electron conduction level of indium copper sulfide (CuInS ₂ ) serving as a photoexciter and the titanium dioxide Since the offset of the electron conduction level becomes an energy value suitable for electron injection into the porous electron transporter, it is possible to increase the injection amount of electrons generated by photoelectric conversion from the photoexciter to the porous electron transporter. Therefore, the conversion efficiency can be improved.

  And the photovoltaic device of the present invention uses any of the above-described photoelectric conversion devices of the present invention as a power generation means, and is configured to supply the generated power of this power generation means to a load, so the conversion efficiency is high, A photovoltaic device having excellent long-term reliability can be provided.

  Hereinafter, an example of an embodiment of a photoelectric conversion device of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a photoelectric conversion device of the present invention. 1 is a substrate, 2 is an electrode, 3 is a porous electron transporter, 4 is a photoexciter, 5 is a counter substrate, and 6 is The counter electrode, 7 is a hole transporter, and 8 is a sealing material. As shown in FIG. 1, the photoelectric conversion device of the present invention includes a photoexciter 4 made of particles mainly composed of indium copper sulfide and performing photoelectric conversion, and a large number of photoexciters 4 attached to the surface. The porous electron transporter 3 for transporting electrons generated by photoelectric conversion in (1) and the hole transporter 7 for transporting holes generated by photoelectric conversion by the photoexciter 4 are provided.

  First, as long as the substrate 1 has a function as a support, for example, a transparent glass substrate, a textured structure formed on the surface of the glass substrate to prevent reflection of light, a translucent glass substrate, A light-transmitting material that transmits light such as a transparent plastic plate, a transparent plastic film, an inorganic transparent crystal, or a colored material such as a metal substrate, a metal film, or a ceramic substrate can be used.

The electrode 2 is a low-resistance material, such as tin oxide, indium oxide, or a composite oxide thereof. Specifically, F (fluorine) or Sb _{In 2 O} 3 -SnO 2, such as _{In 2 O 3, In 4 Sn} 3 O 12 doped with _SnO 2, SnO ₂ and Mn and Mo doped with antimony () A composite oxide is mentioned. Tin oxide, indium oxide, or composite oxides thereof have high transmittance in the visible light region and easily have low resistance among transparent conductive materials. Therefore, the electrode material on the light receiving surface side of the photoelectric conversion device And is particularly preferably used.

  Further, the sheet resistance of the electrode 2 is 20Ω / □ or less, preferably 10Ω / □ or less, and in order to achieve this, an extraction electrode (not shown) made of a mesh metal or the like may be additionally formed. As a material for the extraction electrode, Ag, Al, Cu, Ti, Ni, Fe, Zn, Mo, W or an alloy or compound thereof can be used.

  The electrode 2 can be formed by a vacuum film forming technique such as a sputtering method, a vapor deposition method, an ion plating method, and a CVD method, or by a spray pyrolysis method, a paste method, a dip coating method, or the like. It is possible to form.

  When the substrate 1 is made of a sufficiently low resistance material, the electrode 2 may be omitted and the substrate 1 may have an electrode function.

The porous electron transporter 3 includes In ₂ O ₃ , SnO ₂ , WO ₃ , ZnO, TiO ₂ , Nb ₂ O ₅ , ZrO ₂ , Ta ₂ O ₅ , Ag ₂ O, MnO ₂ , Cu ₂ O ₃ , Fe ₂ O ₃ , V ₂ O ₅ , Cr ₂ O ₃ , NiO, SrTiO ₃ , K ₄ NbO ₁₇ or the like is used. Moreover, you may use the thing which doped a trace amount impurity for the purpose of improving a band gap adjusting material or a charge transport characteristic to these materials. Further, these materials may be used in combination. In particular, it is preferable to use TiO ₂ among these materials. This is because, among metal oxides used as an electron transporter, it is particularly excellent in electron transport properties, has a simple manufacturing process, and is easy to form in a large area. It is.

  Note that a dense layered oxide semiconductor layer having a thickness of about 1 μm or less may be inserted between the electrode 2 and the porous electron transporter 3 by a thin film forming method such as a spin coating method or a dipping method. As a result, since the hole transporter 7 is prevented from coming into direct contact with the electrode 2, the leakage current due to the back electron transfer from the electrode 2 to the hole transporter 7 in the photoelectric conversion device is reduced. The open circuit voltage value can be improved.

  The photoexciter 4 generally indicates a site where carriers are excited by light irradiation. In the photoelectric conversion device of the present invention, the energy level at the bottom of the conduction band of the photoexciter 4 is positioned higher than the energy level at the bottom of the conduction band of the material of the porous electron transporter 3, and The energy difference is preferably about 0.2 eV. This 0.2 eV is a potential difference required when the electrons excited by the photoexciter 4 are transferred to the porous electron transporter 3, and when the energy difference is smaller than this value, the internal electric field is lowered, and the electrons are reduced. This is not preferable because the amount of movement of the electron beam decreases, and on the contrary, even when it is large, the band offset increases and the efficiency of electron injection into the porous electron transporter 3 decreases, which is not preferable.

Here, the present inventors have found that particles made of indium copper sulfide (CuInS ₂ ) are suitable as the material of the photoexciter 4. CuInS ₂ is a compound semiconductor having a chalcopyrite structure having a band gap of about 1.5 eV, and has a large light absorption coefficient in the visible light region, and is therefore a suitable material for the photoexciter 4. Furthermore, since the energy level at the bottom of the conduction band is about 0.1 to 0.4 eV higher than that of TiO ₂ or ZnO which is promising as a material for the porous electron transporter 3, The energy matching is good and the charge transfer from the photoexciter 4 to the porous electron transporter 3 is performed smoothly.

By the way, CuInSe ₂ and CdSe also have a band gap of about 1 to 1.8 eV, and the conduction band energy matching with respect to the porous electron transporter 3 made of TiO ₂ or ZnO is relatively good. And toxic elements such as Se are unsuitable as constituent materials for photoelectric conversion devices that are widely used as consumer devices.

On the other hand, sulfides such as Ag ₂ S, Bi ₂ S ₃ and SnS, which have been studied in the past, are also materials having a high light absorption coefficient in the visible light region, but the energy level at the bottom of the conduction band of these materials. Has a problem that charge transfer from the photoexciter to the porous electron transporter is difficult because it is located on the lower energy side than that of TiO ₂ or ZnO.

FIG. 2 shows a summary of band diagrams relating to some of the above materials. From the band diagram shown in FIG. 2, it can be seen that the photoexciter 4 made of indium copper sulfide (CuInS ₂ ) has good matching with the porous electron transporter 3 made of titanium dioxide (TiO ₂ ).

For the reasons described above, in the photoelectric conversion device of the present invention, the photoexciter 4 is mainly composed of CuInS ₂ , whereby the amount of light absorbed by the photoexciter 4 is large and the generated carriers are efficiently porous. Since it can be injected into the electron transporter 3, a highly efficient photoelectric conversion device made of a non-toxic material can be manufactured. At this time, the material of the porous electron transporter 3 is most preferably titanium dioxide, and the energy at the bottom of the conduction band between the materials with respect to the photoexciter 4 mainly composed of indium copper sulfide (CuInS ₂ ) as described above. Since the difference is estimated to be about 0.2 eV, the charge transfer characteristics are excellent, and as a result, high conversion efficiency can be obtained.

In the photoelectric conversion device of the present invention, the photoexciter 4 is not limited to the above CuInS ₂ as a main component of indium copper sulfide as long as the optical characteristics and electrical characteristics are not significantly deteriorated. A material containing CuIn ₅ S ₈ , CuIn ₅ S ₉ , Cu _1.70 In _0.05 S, CuIn ₁₁ S ₁₇ , Cu ₂ S, In ₂ S ₃ or the like may be used.

The photoexciter 4 is preferably composed of particles, in particular, composed of nanoparticles capable of exhibiting the quantum size effect, and preferably has a particle radius not greater than the effective Bohr radius. For example, it is preferable that the average particle size of less than 20nm in CuInS _2. In addition, when the light absorption edge is shifted remarkably, it is preferable that the average particle diameter is 8 nm or less. Thereby, the amount of absorbed light in the photoexciter 4 increases, and as a result, the short-circuit current value of the photoelectric conversion device can be improved.

  As a method for producing nanoparticles, a gas phase method and a liquid phase method are roughly used. In the case of forming the photoexciter 4 in the photoelectric conversion device of the present invention, it is preferable to use a liquid phase method. Since the liquid phase method can be synthesized in an environment where the substrate temperature is lower than that of the gas phase method, it is possible to suppress damage due to thermal history as much as possible when a transparent conductive film is used as the electrode 2. is there. Furthermore, since the nanoparticles of the photoexciter 4 are grown from the state in which the pores of the porous electron transporter 3 are filled with the liquid for forming the photoexciter 4, the porous electron transporter 3 is moved to the porous electron transporter 3 as compared with the gas phase method. The photoexciter 4 has a good coverage.

  Typical liquid phase methods include chemical precipitation methods such as colloid method, homogeneous precipitation method, alkoxide method, hydrothermal synthesis method and microemulsion method, solvent evaporation such as freeze drying method, spray drying method, and spray pyrolysis method. There is a law. In particular, methods excellent in particle size control include a reverse micelle method and a hot soap method, and a production method using a microcell or a microtube as a reaction field can also be suitably used.

  As long as the counter substrate 5 has a function as a support, for example, a light transmitting material such as a glass substrate, a plastic plate, a plastic film, an inorganic transparent crystal, or a metal substrate, a metal film, or a ceramic is used. A colored material such as a substrate can be used.

The counter electrode 6 is preferably made of a material having high conductivity, and a metal or a transparent conductive layer is suitably used. Specifically, Ag, Al, Cu, Ti, Ni, Fe, Zn, Mo, W or alloys or compounds thereof are used for metals, and SnO ₂ , SnO ₂ , Mn, and Mo doped with F or Sb are used for transparent conductive layers. Examples thereof include In ₂ O ₃ —SnO ₂ composite oxides such as doped In ₂ O ₃ and In ₄ Sn ₃ O ₁₂ .

  Further, when an electrolytic solution is used as the hole transporter 7, platinum, gold, carbon, rhodium, ruthenium, etc. are formed on the counter electrode 5 in order to cause the reduction reaction of redox ions in the electrolytic solution at a sufficient rate. It is preferable to form a catalyst layer (not shown).

  The sheet resistance of the counter electrode 5 is 20Ω / □ or less, preferably 10Ω / □ or less, and in order to achieve this, an extraction electrode (not shown) made of a mesh metal or the like may be additionally formed. . As a material for the extraction electrode, Ag, Al, Cu, Ti, Ni, Fe, Zn, Mo, Au, W, or an alloy or compound thereof can be used.

  Further, when the counter substrate 5 is made of a sufficiently low resistance material, the counter electrode 6 may be omitted and the counter substrate 5 may have an electrode function.

  If the electrolytic solution is used as the hole transporter 7, for example, a material containing a material containing potassium chloride or sodium hydroxide and sodium sulfide or sulfur in an aqueous solution is used. In addition, a mixture prepared by mixing tetrapropylammonium iodide, lithium iodide, iodine or the like with acetonitrile or methoxypropionitrile can be used.

  Examples of the material for the hole transport layer 7 instead of the above include transparent conductive oxides, electrolytes such as gel electrolytes and solid electrolytes, organic hole transport agents, and ultrathin metal films.

Examples of the transparent conductive oxide include CuI, Cu ₂ O, CuS, CuSCN, CoO, NiO, FeO, MoO ₂ and Cr ₂ O ₃ .

  Gel electrolytes are roughly classified into chemical gels and physical gels. A chemical gel is a gel formed by a chemical bond by a cross-linking reaction or the like, and a physical gel is gelled near room temperature due to a physical interaction. The gel electrolyte is a gel obtained by mixing a host polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polyacrylic acid, or polyacrylamide with acetonitrile, ethylene carbonate, propylene carbonate, or a mixture thereof. An electrolyte is preferred. When using a gel electrolyte or solid electrolyte, a low-viscosity precursor is contained in the oxide semiconductor layer, and a two-dimensional or three-dimensional crosslinking reaction is caused by means such as heating, ultraviolet irradiation, or electron beam irradiation. By this, it can be gelled or solidified.

  As the ion conductive solid electrolyte, a solid electrolyte having a polymer chain such as polyethylene oxide, polyethylene oxide or polyethylene having a salt such as a sulfoimidazolium salt, a tetracyanoquinodimethane salt or a dicyanoquinodiimine salt is preferable. As the molten salt of iodide, an iodide such as an imidazolium salt, a quaternary ammonium salt, an isoxazolidinium salt, an isothiazolidinium salt, a pyrazolidium salt, a pyrrolidinium salt, or a pyridinium salt can be used.

  Examples of the aforementioned molten salt of iodide include 1,1-dimethylimidazolium iodide, 1, methyl-3-ethylimidazolium iodide, 1-methyl-3-pentylimidazolium iodide, 1-methyl- 3-isopentylimidazolium iodide, 1-methyl-3-hexylimidazolium iodide, 1-methyl-3-ethylimidazolium iodide, 1,2-dimethyl-3-propylimidazole iodide, 1-ethyl- Examples thereof include 3-isopropylimidazolium iodide and pyrrolidinium iodide.

Examples of the organic hole transport agent include triphenyldiamine and OMeTAD. Further, molten salt electrolytes such as imidazolium salts, triazolium salts and pyridinium salts, LiI, NaI, KI and a mixture of CaI ₂ and I ₂ , or LiBr, NaBr, KBr and a mixture of CaBr ₂ and Br ₂ are used as alcohols, An electrolyte solution or an organic polysilane dissolved in a nitrile compound or a carbonate compound is preferably used.

  As the ultra-thin metal, for example, a metal such as Au formed at 100 nm or less is preferably used.

  The sealing material 8 preferably has a corrosion resistance and moisture absorption preventing function against the material of the hole transporter 7 and has a sufficient adhesive strength. For example, EVA (ethylene vinyl acetate copolymer resin), ethylene-acrylic acid Use ethyl copolymer (EEA), fluororesin, epoxy resin, acrylic resin, saturated polyester resin, amino resin, phenol resin, polyamideimide resin, UV curable resin, silicone resin, fluororesin, urethane resin, or a composite thereof. be able to.

According to the photoelectric conversion device of the present invention configured as described above, a photoexciter 4 that performs photoelectric conversion composed of particles containing indium copper sulfide as a main component, and a large number of the photoexciters 4 adhere to the surface. By providing a porous electron transporter 3 that transports electrons generated by photoelectric conversion in the photoexciter 4 and a hole transporter 7 that transports holes generated by photoelectric conversion in the photoexciter 4, other conventional inorganic transporters are provided. Compared to the case where a semiconductor is used for the photoexciter, the offset between the electron conduction level of the photoexciter 4 and the electron conduction level of the porous electron transporter 3 typified by titanium dioxide is the porous electron transporter 3. Therefore, the amount of electrons and holes generated by photoelectric conversion from the photoexciter 4 to the porous electron transporter 3 and the hole transporter 7 can be increased, and the conversion efficiency can be increased. The It is possible to above. Further, indium copper sulfide (CuInS ₂ ) serving as the photoexciter 4 is stable with respect to thermal energy or light energy corresponding to sunlight, and therefore, stable characteristics can be maintained because it is not altered by active oxygen species or ultraviolet rays. In addition, long-term reliability will be excellent.

  Then, the photovoltaic device of the present invention can be obtained by using the photoelectric conversion device of the present invention as the power generation means and supplying the generated power from the power generation means to the load.

  That is, one or more of the photoelectric conversion devices described above (in the case of multiple photoelectric conversion devices connected in series, parallel or series-parallel) is used as the power generation means, and the generated power is supplied directly to the DC load from this power generation means. do it. In addition, after the DC power output from the above-described photoelectric conversion device is converted into appropriate AC power via power conversion means such as an inverter, this generated power is applied to an AC load such as a commercial power supply system or various electric devices. It is good also as a photovoltaic device which can be supplied. Furthermore, it is also possible to use such a photovoltaic power generation device as a photovoltaic power generation device such as a photovoltaic power generation system in various aspects by installing it in a building with good sunlight. A durable photovoltaic device can be provided.

Example 1
First, a photoelectric conversion device was manufactured using a glass substrate having a thickness of 1.1 mm to be the substrate 1 and fluorine-doped tin oxide to be the electrode 2 formed thereon. The sheet resistance of the electrode 2 was about 10Ω / □.

Next, a TiO ₂ layer to be a porous electron transporter 3 was partially formed on the substrate 1. Specifically, a TiO ₂ paste having an average particle diameter of about 10 nm prepared from the sol-gel method is applied by screen printing, pre-dried at room temperature, and then subjected to sintering heat treatment in a muffle furnace at 450 ° C. for 30 minutes. Was done. Further, a TiO ₂ paste having an average particle size of about 20 to 100 nm is applied by screen printing in an amount of about 20% of the amount of the previous paste, and preliminarily dried at room temperature, and then 450 ° C. in a muffle furnace. A 30 minute sintering heat treatment was performed. At this time, the layer thickness of the sintered TiO ₂ layer was about 10 μm, and it was a porous shape.

At this time, when it is desired to increase the porosity in order to increase the adsorption amount of the photoexciter 4 to be formed later, the molecular weight of 40 to 80% by weight with respect to TiO ₂ is 20,000 at the time of preparing the TiO ₂ paste. About PEG (polyethylene glycol) may be added.

  Then, after being immersed in a 0.1 mol / l titanium tetrachloride solution for 12 hours, heat treatment was again performed in a muffle furnace at 450 ° C. for 30 minutes.

Next, CuInS ₂ particles to be the photoexciter 4 were formed on the porous electron transporter 3. First, a substrate formed by mixing a 15 mmol / l copper sulfate aqueous solution, a 10 mmol / l indium sulfate aqueous solution and a 350 mmol / l sodium thiosulfate aqueous solution, and irradiating it with a low-pressure mercury lamp, up to the porous electron transporter 3 1 was immersed. At this time, the temperature of the mixed aqueous solution was kept at a low temperature of 0 to 10 ° C., and the reaction rate was controlled so that the crystal growth did not proceed rapidly. Thereafter, heat treatment was performed at 400 ° C. for 1 hour in a muffle furnace.

Incidentally, the X-ray diffraction spectrum of the powder obtained when CuInS ₂ particles are formed alone without immersing the substrate 1 under the above conditions is shown in FIG. From the results shown in FIG. 3, it can be seen that CuInS ₂ having a composition of stoichiometric ratio is formed in the photoexciter 4 formed in this way.

  Next, a substrate in which the fluorine-doped tin oxide and Pt layer to be the counter electrode 6 are patterned on the glass substrate to be the counter substrate 5, and the photoexciter 4 as described above, a sealing material 8 and The surroundings were sealed by local heating leaving an electrolyte injection hole (not shown).

  Subsequently, a solution in which a small amount of sulfur is dissolved in a mixed solution of a 0.1 mol / l sodium sulfite aqueous solution and a 0.4 mol / l sodium sulfide aqueous solution to be the hole transport layer 7 is injected from an electrolyte solution injection hole provided in the counter substrate 5. did. Finally, the electrolyte injection hole was sealed with an epoxy resin.

About Example 1 of the photoelectric conversion apparatus of this invention produced as mentioned above, the pseudo-sunlight with which incident light intensity was adjusted to 100 mW / cm < ² > was irradiated, and the characteristic evaluation was performed.

In addition, as a comparative example (conventional example 1), the photoelectric conversion device using CdSe nanoparticles as the photoexciter in Example 1 was also evaluated. The formation of the CdSe nanoparticles on the porous charge transporter was carried out by using a small amount of selenium in 0.1 mol / l cadmium sulfate aqueous solution, 0.1 mol / l trisodium nitrilotriacetate aqueous solution and 0.1 mol / l potassium sulfite aqueous solution. This was performed by immersing a substrate on which TiO _{2 serving} as a porous charge transporter was formed in the dissolved mixed solution.

  As a result of evaluating the characteristics of the photoelectric conversion devices of Example 1 and Comparative Example (Conventional Example 1) of the present invention, the conversion efficiency of Inventive Example 1 is 2.18%, greatly exceeding 0.75% of Conventional Example 1. It was a conversion characteristic.

(Example 2)
In the same manner as in Example 1, a TiO ₂ layer serving as the porous electron transporter 3 was formed on the substrate 1 on which the electrode 2 was formed. Furthermore, CuInS ₂ particles that form the semiconductor portion of the photoexciter 4 were formed on the porous electron transporter 3.

  First, a solution prepared by dissolving indium chloride and copper chloride in deionized water at 0.3 mol / l was prepared. To this aqueous solution, thiourea was mixed so as to have a concentration of 4 mol / l, and in order to promote dissociation of sulfur from thiourea, 25% by mass of aqueous ammonia was added until the pH of the solution reached 11. The substrate 1 prepared up to the porous electron transporter 3 was immersed in the aqueous solution thus prepared for 24 hours. Next, the substrate 1 taken out from the aqueous solution was heat-treated at 400 ° C. for 30 minutes in a vacuum.

Thereafter, Example 2 of the photoelectric conversion device of the present invention was produced in the same manner as Example 1, and the characteristics evaluation was performed by irradiating it with pseudo-sunlight whose incident light intensity was adjusted to 100 mW / cm ² . As a result, the conversion efficiency of Example 2 was as good as 1.70%.

(Example 3)
In the same manner as in Example 1, a TiO ₂ layer serving as the porous electron transporter 3 was formed on the substrate 1 on which the electrode 2 was formed. Furthermore, CuInS ₂ particles that form the semiconductor portion of the photoexciter 4 were formed on the porous electron transporter 3.

  First, ethylenediamine was put in an autoclave container, and copper, indium, and sulfur powders were added so as to be 0.01 mol / l, 0.01 mol / l, and 0.02 mol / l, respectively. This was heated to 280 ° C. and held for 24 hours. Thereafter, when the temperature of the solution became 200 ° C. or lower, the substrate 1 formed up to the porous electron transporter 3 was immersed. Next, the substrate 1 taken out of the solution was washed with pure water, and then heat-treated at 400 ° C. for 30 minutes in a vacuum.

Thereafter, Example 3 of the photoelectric conversion device of the present invention was produced in the same manner as Example 1, and the characteristics were evaluated by irradiating the same with pseudo-sunlight whose incident light intensity was adjusted to 100 mW / cm ² . As a result, the conversion efficiency of Example 3 was as good as 1.44%.

  In addition, this invention is not limited to the example of the above embodiment, A various change may be added in the range which does not deviate from the summary of this invention. For example, the photoelectric conversion device of the above embodiment and a silicon-based photoelectric conversion device or a dye-sensitized solar cell may be stacked, and according to this, each photoelectric conversion device is configured to complement each other's light absorption region. Therefore, when the multi-terminal parallel tandem structure is used, the short circuit current value can be improved, and when the series tandem structure is used, the open circuit voltage can be improved.

It is sectional drawing which shows an example of embodiment of the photoelectric conversion apparatus of this invention. The band diagram regarding the material of the photoexcitation body in this invention and other materials, and the material of a porous electron transport body is put together. It is an example of the X-ray diffraction spectrum of the photoexcited body in the photoelectric conversion apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Electrode 3 ... Porous electron transporter 4 ... Photoexciter 5 ... Opposite substrate 6 ... Counter electrode 7 ... Hole transporter 8 ... Sealing Material

Claims (5)

A photo-exciter that performs photoelectric conversion, composed of particles containing indium copper sulfide as a main component, and a porous electron transporter that transports electrons generated by photoelectric conversion in the photo-exciter, in which a large number of the photo-exciters adhere to the surface; And a hole transporter that transports holes generated by photoelectric conversion by the photoexciter. The photoelectric conversion device according to claim 1, wherein an average particle diameter of the photoexciter is 20 nm or less. The photoelectric conversion device according to claim 1, wherein the photoexciter is formed on a surface of the porous electron transporter by a liquid phase method. The photoelectric conversion device according to claim 1, wherein the porous electron transporter contains titanium dioxide as a main component. 5. A photovoltaic power generation apparatus using the photoelectric conversion apparatus according to claim 1 as a power generation means, and supplying the generated power of the power generation means to a load.

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