JP4637523B2 - Photoelectric conversion device and photovoltaic device using the same - Google Patents

Description

  The present invention relates to a photoelectric conversion device such as a solar cell or a light receiving element using a novel material that can be expected to have high photoelectric conversion efficiency, and a photovoltaic device using the photoelectric conversion device.

  A dye-sensitized solar cell, which is one of photoelectric conversion devices, is considered advantageous for cost reduction because it does not require high-temperature treatment or a vacuum device, and has recently been researched and developed rapidly. In this dye-sensitized solar cell, for example, a porous titanium oxide layer obtained by sintering fine particles having a particle diameter of about 20 nm is provided on a conductive glass substrate, and the dye is applied to the particle surface of the porous titanium oxide layer. A single molecule adsorbed electrode is used as a photoworking electrode, and a conductive glass counter electrode sputtered with platinum is filled with an electrolyte solution containing an iodine / iodide redox pair, and the electrolyte solution is sealed. By making such a porous structure, the surface area of the light working electrode can be increased by 1000 times or more, and light absorption by the adsorbing dye can be efficiently performed to generate photovoltaic power.

However, metal complex dyes that give high conversion efficiency, especially ruthenium complex dyes, are dyes having short wavelength photosensitivity, and conversion efficiency is insufficient with a single photoelectric conversion device in which such a dye is supported on a porous semiconductor layer. there were. For this reason, new ruthenium complex dyes such as black dyes with improved long wavelength photosensitivity have been developed, and the light absorption wavelength range has been expanded to the long wavelength range, but the conversion efficiency has not been improved as expected.

  In addition, various organic dyes that are metal-free, particularly ruthenium-free, have been developed. However, nothing more than ruthenium complex dyes has been found, and research and development has been conducted energetically. In organic dyes, techniques such as increasing the conjugate length of dye molecules have been researched and developed in order to give the dye long wavelength sensitivity. Thus, even if it is limited to the conversion efficiency, it is a severe situation to reach the market, and further improvement of the photoelectric conversion efficiency is required.

  Next, an example of a conventional photoelectric conversion device in which the dye is not single and a photoelectric conversion device in which the porous semiconductor layer carrying the dye is not single will be described.

  Patent Document 1 discloses a solar cell that effectively uses a light absorption wavelength region by using a dye layer composed of at least two different dyes. Specifically, such a solar cell includes a step of bringing a porous semiconductor layer into contact with a solution containing a first dye charged to a predetermined polarity to adsorb the first dye, It is formed by bringing the second dye into contact with a solution containing the second dye charged to a polarity opposite to that of the dye and causing the first dye to adsorb the second dye.

  Patent Document 2 discloses that two types of different dyes each exhibit a maximum value of the incident light quantum yield at different incident wavelengths, and use a light having a wide range of wavelengths and have high conversion efficiency. A conversion device is disclosed.

  Patent Document 3 discloses a solar cell (photoelectric conversion element) having a plurality of semiconductor layers carrying dyes having different absorption wavelengths. In the production of this solar cell, by repeating the steps of adsorbing the pigment on the oxide semiconductor particles, drying, and then forming and drying using a paste mixed with a binder dissolved in alcohol The oxide semiconductor layer in which each dye is adsorbed is formed.

  In addition, according to the dye-sensitized solar cell disclosed in Patent Document 4, the porosity is obtained by adsorbing a complex dye in which at least two kinds of dyes having different maximum light absorption wavelengths are chemically adsorbed to each other as the sensitizing dye. By providing a semiconductor layer and having two coloring systems, it is possible to provide a solar cell with a wide light absorption wavelength range, a large amount of light absorption, and a high photoelectric conversion efficiency as compared with a conventional solar cell. . Specifically, a method for producing a dye-sensitized solar cell having a porous semiconductor layer on which a dye is adsorbed and a carrier transport layer between a transparent conductive film formed on the surface of the transparent substrate and a conductive substrate In (1), the substrate on which the porous semiconductor layer is formed is dipped in a solution in which the first dye having a shortest maximum sensitivity wavelength region is dissolved to adsorb the first dye to the porous semiconductor layer, or a transparent conductive film is formed. The formed substrate is immersed in a mixed solution of a semiconductor material to be a porous semiconductor layer and a first dye, and a porous semiconductor layer in which the first dye is adsorbed by an electrochemical reaction is formed on the transparent conductive film, and then The porous semiconductor layer on which the first dye is adsorbed is immersed in a solution in which the second dye having a long maximum sensitivity wavelength region is dissolved, and the first dye (having a carboxyl group) and the second dye (having a hydroxyl group) are chemically treated. Reaction (chemisorption bonding) There is one and forming a body pigment. In addition, (2) the first dye having a short maximum sensitivity wavelength region and the second dye having a long maximum sensitivity wavelength region are chemically reacted (chemisorption bonding) to prepare a composite dye, and then the porous semiconductor layer is formed. There has been proposed a substrate characterized in that the formed substrate is immersed in a solution in which a complex dye is dissolved, and the complex dye is adsorbed on a porous semiconductor layer.

According to the composite solar cell disclosed in Patent Document 5, a dye-sensitized solar cell is disposed on the side facing the sunlight, and a bulk-type crystalline silicon solar cell is disposed behind the dye-sensitized solar cell. To form a composite solar cell. According to this, a dye-sensitized solar cell using a ruthenium complex is disposed on the side facing the sunlight, and power is generated by light having a wavelength of 300 nm to 600 nm. On the other hand, a bulk crystalline silicon solar cell is arranged on the back side of the dye-sensitized solar cell, and is configured to generate power at a wavelength of 400 nm to 1100 nm among the light transmitted through the dye-sensitized solar cell. Yes.

In general, bulk-type crystalline silicon solar cells have excellent weather resistance and have a durability of 20 years or more, so the bulk-type crystalline silicon solar cells alone are rapidly expanding the market. In this bulk-type crystalline silicon solar cell, a pn semiconductor junction is usually formed on a silicon semiconductor substrate made of a single material of high purity and having a thickness of about 250 μm to perform photoelectric conversion. Although sunlight and visible light have a wide wavelength spectrum, there is a limit on the wavelength of absorption and power generation of light energy due to the band gap of the semiconductor, so there is a limit in photoelectric conversion efficiency in a photoelectric conversion device made of a single inorganic material .

In addition, since a thick silicon semiconductor substrate requires a large amount of expensive high-purity silicon material, for the popularization of solar cells to general households, the appearance of low-cost solar cells with few expensive silicon materials is eagerly desired. . Here, the thin-film amorphous silicon solar cell is a thin silicon film (usually about 0.3 μm in thickness) and can be produced at low cost, but the conversion efficiency alone is low and the market has not been expanded.

  In addition, a stacked thin film silicon solar cell having a structure in which an amorphous silicon photoelectric conversion device and a microcrystalline silicon photoelectric conversion device are stacked with a thin film has attracted attention. Even with the same silicon, amorphous and microcrystals have different band gaps. By stacking these two photoelectric conversion devices, we can expect to broaden the sunlight spectrum and increase conversion efficiency. Mass production has begun.

In such a stacked thin film silicon solar cell, the amorphous silicon photoelectric conversion device has a thin film thickness of about 0.2 μm, but the microcrystalline silicon photoelectric conversion device has a large film thickness of about 2 μm. Therefore, since the manufacturing cost of the microcrystalline silicon photoelectric conversion device is one digit higher than that of the thin film amorphous silicon solar cell, the equipment cost is increased and the cost cannot be reduced and the market has not been expanded.
JP 2000-195569 A JP 2000-268892 A JP 2000-243466 A JP 2002-343455 A JP 2002-231324 A

  As described above, the dye-sensitized solar cell is considered as a solar cell that can be manufactured at the lowest cost because it does not require high-temperature treatment or a vacuum apparatus. However, the conversion efficiency is low and it does not reach the bulk type crystalline silicon solar cell and the laminated thin film silicon solar cell. This conversion efficiency improvement is the first problem. In addition, new ruthenium complex dyes such as black dyes with improved long wavelength photosensitivity have been developed, but the conversion efficiency has not been improved as expected. Furthermore, various organic dyes that are free of metal, particularly ruthenium-free dyes, have been developed. However, nothing more than ruthenium complex dyes has been found, and various research and development have been actively conducted. For example, techniques such as increasing the conjugate length of dye molecules have been used in order to give the dye long wavelength sensitivity, but the dye molecules themselves become larger and have a higher molecular weight, making it difficult to dissolve in solvents. Thus, adsorption to the porous oxide semiconductor becomes difficult.

  According to the techniques disclosed in Patent Document 1 and Patent Document 2, it is said that the light absorption wavelength region can be effectively used by using a dye layer composed of at least two different dyes. Specifically, the porous semiconductor layer is brought into contact with a solution containing a first dye charged to a predetermined polarity to adsorb the first dye, and the first dye is charged with a reverse polarity. The first dye is brought into contact with the solution containing the second dye and the second dye is adsorbed to the first dye. Thus, in a solar cell using a dye layer composed of two or more different dyes, various troubles occur due to in-process interaction between the two kinds of dyes, resulting in unstable photoelectric conversion efficiency, and the porous semiconductor. There is a problem that the number of steps for supporting the layer increases. Further, when two or more different dyes are adsorbed simultaneously, it is difficult to adsorb a predetermined amount of dye because the adsorption speed of each dye is different.

  Patent Document 3 proposes a solar cell (photoelectric conversion element) having a plurality of semiconductor layers carrying dyes having different absorption wavelengths. In the production of this solar cell, by repeating the steps of adsorbing the pigment on the oxide semiconductor particles, drying, and then forming and drying using a paste mixed with a binder dissolved in alcohol The oxide semiconductor layer in which each dye is adsorbed is formed. In such a manufacturing method, since a sintering process cannot be performed, contact between oxide semiconductor particles is poor, resistance is increased, and a high-performance solar cell cannot be manufactured.

  Moreover, in the dye-sensitized solar cell disclosed in Patent Document 4, as a sensitizing dye, a porous semiconductor layer in which a composite dye in which at least two kinds of dyes having different maximum light absorption wavelengths are chemically adsorbed to each other is adsorbed And having two color developing systems, it is said that a solar cell having a wide light absorption wavelength region, a large amount of light absorption, and high photoelectric conversion efficiency can be provided as compared with a conventional solar cell. However, in the first production method in which two or more dyes are sequentially supported, the photoelectric conversion efficiency is unstable due to various troubles due to the interaction between the two kinds of dyes, and the supporting process to the porous semiconductor layer There is a problem that increases. In addition, in the second production method in which two or more kinds of dyes are chemically reacted (chemisorption bonding) in advance to prepare and carry a complex dye, the complex dye is chemically reacted to three or more molecules in a solution ( There is a problem that the molecule of the complex dye becomes large due to chemical adsorption bonding, and the dye does not penetrate into the porous semiconductor layer.

  Further, the dye-sensitized solar cell has a problem of durability, and it is important to solve the problem of durability particularly in outdoor use. In dye-sensitized solar cells, a dye is supported on titanium dioxide or the like, and there is a concern that the dye may be deteriorated by ultraviolet rays or short-wavelength light. Under strong sunlight, it is considered to suppress the photodegradation of the dye by inserting an ultraviolet absorbing film on the light incident side, but it is doubtful whether this method can completely suppress the photodegradation. In addition, insertion of an ultraviolet absorbing film or the like also causes visible light absorption, leading to a decrease in photoelectric conversion efficiency.

  According to the composite solar cell disclosed in Patent Document 5, a dye-sensitized solar cell is disposed on the side facing the sunlight, and a bulk-type crystalline silicon solar cell is disposed behind the dye-sensitized solar cell. To form a composite solar cell. In this case, even if the conversion efficiency is superior to that of the bulk crystalline silicon solar cell, it does not solve the problem of cost reduction and durability.

Thin-film amorphous silicon solar cells are thin silicon films (usually about 0.3 μm thick)
Therefore, low-cost production is possible, but the conversion efficiency alone is low and the market has not been expanded.

  In addition, a stacked thin film silicon solar cell having a configuration in which an amorphous silicon photoelectric conversion device and a microcrystalline silicon photoelectric conversion device are stacked in a thin film has a wider solar spectrum by stacking two photoelectric conversion devices. The conversion efficiency is improved by covering, but the cost is not reduced.

  Furthermore, in dye-sensitized solar cells, there is a concern that photodegradation of the dye may occur due to ultraviolet light or short wavelength light. Particularly, the photodegradation of the pigment is accelerated by the heat of sunlight. At present, practical application for indoor use is first considered, but this is not a true solar cell. Insertion of an ultraviolet absorbing film or the like also absorbs visible light and lowers the photoelectric conversion efficiency, so it cannot be used actively. As described above, the conventional dye-sensitized solar cell has a problem in weather resistance because anxiety about light deterioration and heat deterioration of the dye has not been solved yet.

  The present invention has been made in view of such circumstances, and an object thereof is to increase the conversion efficiency, and to provide a photoelectric conversion device capable of reducing cost and durability, and a photovoltaic device using the photoelectric conversion device. .

In order to achieve the above object, the photoelectric conversion device of the present invention is characterized in that 1) a dye monomer having a porphyrin skeleton and an aggregate are mixed or laminated and used as a photoelectric conversion material.

2) A metal oxide semiconductor in which a monomer and an aggregate of a dye having a porphyrin skeleton and performing photoelectric conversion are adsorbed or stacked on a conductive support is present in the electrolyte. You may employ | adopt the structure characterized by arrange | positioning in the state.

  Furthermore, the photovoltaic device of the present invention is characterized in that the photoelectric conversion device of 1) or 2) above is used as a power generation means, and the generated power of this power generation means is supplied to a load.

Since the photoelectric conversion device of the present invention is used as a photoelectric conversion material by mixing or laminating a monomer of a dye having a porphyrin skeleton and an aggregate, the conjugate length is widened and stabilized by the transition dipole interaction of a plurality of molecules. As a result, high sensitivity and wide sensitivity can be obtained on the long wavelength side (450 nm or more) of incident sunlight, which could not be found conventionally, and conversion efficiency and durability can be improved. Further, it is possible to provide a photoelectric conversion apparatus in a short because even with a high sensitivity to a wavelength side by superposition effect of the long-wavelength side, such as a solar cell or a sensor that is durable good Ri efficiency of the incident light. Furthermore, such an aggregate of a dye having a porphyrin skeleton can be prepared by a simple process in which an acid is allowed to act on a monomer. Thereby, the photoelectric conversion device of the present invention alone, or a combination of a dye-sensitized solar cell or a thin-film solar cell having high sensitivity on the short wavelength side, a solar cell, a sensor, or the like that is easier to manufacture with higher efficiency A photoelectric conversion device can be provided.

In addition, a metal oxide semiconductor in which a monomer and an aggregate of a pigment having a porphyrin skeleton and photoelectric conversion are mixed and adsorbed or stacked on a conductive support is present in an electrolyte. For the reasons described above, the photoelectric conversion device alone of the present invention, or a dye-sensitized solar cell or a thin-film solar cell having high sensitivity on the short wavelength side, is combined for higher efficiency and durability. A photoelectric conversion device such as a certain dye-sensitized solar cell can be easily provided.

  Furthermore, the photovoltaic device of the present invention is characterized in that the photoelectric conversion device of 1) or 2) above is used as a power generation means, and the generated power of this power generation means is supplied to a load. An efficient and durable photovoltaic device can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same members are denoted by the same reference numerals.

FIG. 1 is a cross-sectional view schematically illustrating a photoelectric conversion device as a reference constituting the basic structure of a dye-sensitized solar cell, and FIG. 2 is a cross-sectional view schematically illustrating a stacked photoelectric conversion device as a reference . Respectively. An arrow L in the figure indicates a state (direction) of incident light.

  The photoelectric conversion device shown in FIG. 1 is a metal oxide in which a dye aggregate (hereinafter referred to as dye aggregate) 13 having a porphyrin skeleton is adsorbed on a conductive substrate 11 which is a conductive support. An electron transporter (metal oxide semiconductor) 12 that is a one-conductivity type transporter made of a semiconductor is disposed in a state of being present in an electrolyte that is the other conductivity-type transporter. This structure forms a dye-sensitized photoelectric converter that performs photoelectric conversion by the sensitizing action of the dye aggregate 13, and this dye-sensitized photoelectric converter is formed on the conductive substrate 11 and is dye-aggregated. Porous electron transporter 12 carrying 13, electrolyte 14 which is a reverse porous reverse conductivity type transporter formed so as to fill this electron transporter 12, transparent conductive layer 17 carrying platinum or carbon, and transparent It consists of a light coating 18.

  The photoelectric conversion device of FIG. 2 has a dye aggregate 13 on one main surface of a conductive substrate 11 on which light is incident from one main surface side, and a dye that performs photoelectric conversion by the sensitizing action of the dye aggregate 13. A laminated photoelectric conversion device comprising a sensitized photoelectric conversion body and a thin film photoelectric conversion body manufactured by a thin film formation method and having an inorganic semiconductor layer for photoelectric conversion and transmitting light. The dye-sensitized photoelectric converter has a peak sensitivity on the longer wavelength side than the thin film photoelectric converter and absorbs light transmitted through the thin film photoelectric converter.

  The thin film photoelectric converter has a configuration in which a thin film photoelectric conversion layer 16, a second transparent conductive layer 17, and a translucent covering 18 are sequentially laminated on a first transparent conductive layer 15. The thin film photoelectric conversion layer 16 may be a silicon thin film pin junction layer or a compound semiconductor thin film junction layer such as CIGS (CuInGaSe). These junction layers are preferably those that generate an internal electric field, such as a pin junction type, a pn junction type, a Schottky junction type, and a hetero junction type. As silicon-based materials, amorphous silicon-based materials, amorphous silicon-based materials including nano-sized crystals, microcrystalline silicon-based materials, etc. are particularly suitable. Is good. Here, the amorphous silicon system includes alloy systems such as amorphous silicon carbide and amorphous silicon nitride.

  The first output from the thin film photoelectric converter and the second output from the dye-sensitized photoelectric converter may be output independently or connected to each other. In the case of a stacked photoelectric conversion device as in the present invention, if the performance of both photoelectric conversion devices is matched so that the current of the first output and the current of the second output are the same, the first transparent There is no need to extract the output from the electrode layer to the outside, and the electrode wiring structure such as integration is simple and good. In order to match both photocurrents, the film thickness, sensitivity, etc., may be adjusted.

In one embodiment of the photoelectric conversion device of the present invention, as shown in FIG. 3, not only the dye aggregate 13 but also a dye (free base or protonated monomer) dye (dye monomer) 19 is suitable as the dye. and it has a structure obtained by mixing at a ratio. Here, the ratio of the dye aggregate 13 to the dye monomer 19 can be appropriately controlled by the acid treatment time, temperature, concentration and the like. According to this photoelectric conversion device, since the dye monomer 19 and the dye aggregate 13 are mixed, the absorption wavelength can be widened, and conversion efficiency and durability can be improved.

As another embodiment of the photoelectric conversion device of the present invention, as shown in FIG. 4, a photoelectric conversion body 2a having a dye monomer 19 and a dye aggregate 13 are provided with a conductive substrate 11 interposed therebetween. It is also possible to have a structure in which the photoelectric converter 2b is laminated. Also in this stacked photoelectric conversion device, since the dye monomer 19 and the dye aggregate 13 are provided on both sides of the conductive substrate, the light absorption wavelength can be widened, and the conversion efficiency is improved and the durability is improved. be able to.

  Next, each element which comprises the photoelectric conversion apparatus mentioned above is demonstrated in detail.

<Conductive substrate>
The conductive substrate 11 may have a thin metal sheet alone, titanium, stainless steel, aluminum, silver, copper, a good and nickel. Further, a resin impregnated with carbon or metal fine particles or fine lines, a conductive organic resin, or the like is preferable. Also, an insulating substrate with a conductive film 11b such as Ti / ITO / Ti in a laminated body, such as ITO, SnO ₂ : F, ZnO: Al as a transparent conductive film, such as titanium, stainless steel, aluminum, silver, copper, or nickel as a metal thin film 11a is good. As a material of the insulating substrate 11a, resin materials such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyimide, polycarbonate, inorganic materials such as blue plate glass, soda glass, borosilicate glass, ceramics, and conductive organic resin materials Organic-inorganic hybrid materials are good.

If the conductive substrate 11 has light reflectivity, the transmitted light can be reflected and reused. In the case of a metal substrate, silver or aluminum is preferable. Further, in the case of the conductive film 11b, a laminated film of silver, Ti / Ag / Ti with an adhesion layer, or the like is preferable, and it is preferably formed by a vacuum deposition method, an ion plating method, a sputtering method, an electrolytic deposition method, or the like. The thickness of the conductive substrate is 0.01 mm to 5 mm, preferably 0.02 mm to 3.0 mm. The thickness of the conductive film is 0.001 μm to 10 μm, preferably 0.05 μm to 2.0 μm. Further, when the conductive substrate 11 is translucent (eg, SnO ₂ : blue plate glass with F film), the back surface of the substrate may be light-reflected using a sheet or film of light-reflective aluminum or silver. I do not care.

In the case of FIGS. 1 to 4 , if the conductive substrate 11 has translucency, light can be incident from the electron transporter 12 side. In this case, as the material of the insulating substrate 11a, resin sheets such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyimide, polycarbonate, etc., white sheets, soda glass, soda glass, borosilicate glass, ceramics and other inorganic sheets, organic inorganic Hybrid seats are good. Similarly, the transparent conductive film 11b is preferably a tin-doped indium oxide film (ITO film) or an impurity-doped indium oxide film (In ₂ O ₃ film) produced by a low temperature growth sputtering method or a low temperature spray pyrolysis method. In addition, an impurity-doped zinc oxide film (ZnO film) manufactured by a solution growth method may be used, and these may be stacked and used. Alternatively, a fluorine-doped tin dioxide film (SnO ₂ : F film) formed by a thermal CVD method may be used. In addition, an impurity-doped indium oxide film (In ₂ O ₃ film) or the like can be used. As other film forming methods, there are a vacuum deposition method, an ion plating method, a dip coating method, a sol-gel method, and the like. The formation of surface irregularities in the order of the wavelength of incident light by the growth of these films is still preferable because of the light confinement effect. The first transparent conductive layer may be a thin metal film such as Au, Pd, or Al formed by a vacuum deposition method or a sputtering method.

  Further, the surface on the light incident side of the conductive substrate 11 may be flat on both sides, but the surface having irregularities in the order of the wavelength of incident light may have a light confinement effect.

<Electron transporter>
As the electron transporter 12 which is one conductivity type transporter, an electron transporter (n-type metal oxide semiconductor) such as porous titanium dioxide is particularly preferable. In the case of the photoelectric conversion device of FIGS . 1 to 4, the porous electron transporter 12 is formed on the conductive substrate 11.

  The electron transporter 12 is preferably an n-type metal oxide semiconductor, and is most preferably an aggregate of a plurality of granular bodies or linear bodies (needle bodies, tube bodies, columnar bodies, etc.).

  By making the electron transporter 12 a porous body or the like, the bonding area is expanded, the surface area for supporting the dye is increased, and the photoelectric conversion efficiency can be increased.

  In addition, by making the electron transporter 12 a porous body or the like, the surface of the dye-sensitized photoelectric conversion body becomes uneven, bringing a light confinement effect to the thin film photoelectric conversion body or the dye-sensitized photoelectric conversion body, Photoelectric conversion efficiency can be further increased.

As the material and composition of the metal oxide semiconductor, titanium oxide (TiO ₂ ) is optimal, and as other material and composition, titanium (Ti), zinc (Zn), tin (Sn), niobium (Nb), Indium (In), Yttrium (Y), Lanthanum (La), Zirconium (Zr), Tantalum (Ta), Hafnium (Hf), Strontium (Sr), Barium (Ba), Calcium (Ca), Vanadium (V), etc. Non-metals such as nitrogen (N), carbon (C), fluorine (F), sulfur (S), chlorine (Cl), and phosphorus (P) are preferable. One or more elements may be contained. In any case, an n-type semiconductor whose electron energy band gap is in a range of 2 eV to 5 eV larger than the energy of visible light and whose conduction band of the metal oxide semiconductor is lower than the conduction band of the dye in the electron energy level is preferable.

This metal oxide semiconductor is preferably a porous body having a porosity of 20% to 80%, more preferably 40% to 60%. This is because the surface area of the light working electrode can be increased 1000 times or more by making the porosity of this degree of porosity, and light absorption, power generation and electron conduction can be performed efficiently. The shape of the porous body is preferably a shape having a large surface area and a small electric resistance, and is usually preferably composed of fine particles or fine lines, and has an average particle diameter or average wire diameter of 5 nm to 500 nm. More preferably, the thickness is 10 nm to 200 nm. Here, when the average wire diameter is lower than 5 nm to 500 nm, the material cannot be miniaturized, and the upper limit is
This is because if it exceeds this range, the junction area is reduced and the photocurrent is significantly reduced.

The film thickness of the metal oxide semiconductor is preferably 0.1 μm to 50 μm, more preferably 1 μm to 20 μm.
m. Here, the lower limit value between 0.1 μm and 50 μm cannot be used practically because the photoelectric conversion effect becomes extremely small when the film thickness is smaller than this, and the upper limit value is that light cannot be transmitted when the film thickness becomes thicker than this. This is because no longer enters.

The titanium oxide semiconductor is manufactured by first adding acetylacetone to TiO ₂ anatase powder and then kneading with deionized water to produce a titanium oxide paste stabilized with a surfactant. The prepared paste is applied at a constant speed onto the surface on which the translucent conductive film is formed by the doctor blade method, and is 300 to 600 ° C., preferably 400 to 500 ° C. in the atmosphere for 10 minutes. A porous metal oxide semiconductor is produced by treatment for ˜60 minutes, preferably 20 minutes to 40 minutes. This method is simple and effective when it can be formed in advance on a heat-resistant conductive substrate as shown in FIG.

As a low-temperature growth method of such a metal oxide semiconductor, an electrodeposition method, an electrophoretic electrodeposition method, a hydrothermal synthesis method, or the like is preferable, and microwave processing, CVD / UV processing, or the like is preferable as post-processing. As a material for the metal oxide semiconductor, porous ZnO by electrodeposition, porous TiO ₂ by electrophoretic deposition, or the like is preferable.

<Dye>
The dye has a porphyrin skeleton that facilitates the formation of aggregates. In addition, in order to efficiently absorb sunlight, a dye is adsorbed on a porous metal oxide semiconductor, so that the dye has at least one carboxyl group, sulfonyl group, hydroxamic acid group, alkoxy group, aryl group, phosphoryl group. It is effective to have as a substituent. FIG. 5 shows a state in which phenylporphyrin has a substituent. For example, all of the substituents R1 to R4 attached to the porphyrin skeleton may be a carboxy group, or 3 or less of the substituents R1 to R4 may be a carboxy group, and the rest may be hydrogen. Here, the substituent may be any as long as it can strongly chemisorb the dye itself to the metal oxide semiconductor and can easily transfer charges from the excited dye to the metal oxide semiconductor.

  Examples of a method for adsorbing a dye on a porous metal oxide semiconductor include a method in which a substrate on which a metal oxide semiconductor is formed is immersed in a solution in which the dye is dissolved. When the substrate on which the porous metal oxide semiconductor is formed is immersed in the solution in which the dye is dissolved, the temperature of the solution and the atmosphere is not particularly limited, and examples include immersion under atmospheric pressure and room temperature. The time can be appropriately adjusted depending on the type of the dye, the solvent, the concentration of the solution, the temperature, and the like. Thereby, a pigment | dye can be made to adsorb | suck to a porous metal oxide semiconductor.

  Examples of the solvent used for dissolving the dye include a mixture of one or more alcohols such as ethanol, ketones such as acetone, ethers such as diethyl ether, nitrogen compounds such as acetonitrile, and the like.

Further, the dye concentration in the solution is preferably about 5 × 10 ⁻⁵ to 2 × 10 ⁻³ mol / l.

  The dye aggregate 13 can be formed by increasing the dye adsorption concentration or protonating the dye with an acid. When the dye is protonated with an acid such as nitric acid, sulfuric acid, hydrochloric acid or acetic acid to form the dye aggregate 13, the dye is adsorbed on a porous one-conductivity transporter, and then acid-treated, and the dye aggregate 13 And a method of adsorbing the dye aggregate 13 to a porous one-conductivity transporter after forming a dye aggregate in a solution or on the surface of the solution with an acid.

By mixing or laminating the dye monomer 19 and the dye aggregate 13 as described above, the respective light absorption wavelength widths can be combined to increase the overlap with a wide range of wavelengths of sunlight, improving the photoelectric conversion efficiency. Can be made.

<Electrolyte>
The electrolyte 14 which is a reverse porous and other conductive type transporter is particularly preferably a hole transporter such as a gel electrolyte (p-type semiconductor, liquid electrolyte, solid electrolyte, electrolytic salt, etc.). Here, the reverse porous body is formed so as to fill the porous body, and the electrolyte solution exhibits the best carrier movement, but gelation and solidification are preferred because of problems such as liquid leakage.

Examples of the electrolyte material include transparent conductive oxides, electrolyte solutions, electrolytes such as gel electrolytes and solid electrolytes, organic hole transport agents, and ultrathin metal films. As the transparent conductive oxide, a compound semiconductor containing monovalent copper, GaP, NiO, CoO, FeO, Bi ₂ O ₃ , MoO ₂ , Cr ₂ O _{3, and the} like are preferable. Among them, a semiconductor containing monovalent copper is preferable. Good. Suitable compound semiconductors include CuI, CuInSe ₂ , Cu ₂ O, CuSCN, CuS, CuInS ₂ , and CuAlSe _2. Among these, CuI and CuSCN are preferred, and CuI is most preferable because it is easy to manufacture.

  As the electrolyte solution, a quaternary ammonium salt or a Li salt is used. As the composition of the electrolyte solution, for example, a solution prepared by mixing ethylene carbonate, acetonitrile, methoxypropionitrile, or the like with tetrapropylammonium iodide, lithium iodide, iodine, or the like can be used.

  Gel electrolytes are roughly classified into chemical gels and physical gels. A chemical gel is a gel formed by chemical bonding by a cross-linking reaction or the like, and a physical gel is gelled near room temperature due to physical interaction. The gel electrolyte is a gel that is polymerized by mixing a host polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polyacrylic acid, or polyacrylamide into 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 included 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. 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 sulfonimidazolium salt, a tetracyanoquinodimethane salt or a dicyanoquinodiimine salt is preferable. As the molten salt of iodide, iodides such as imidazolium salt, quaternary ammonium salt, isoxazolidinium salt, isothiazolidinium salt, pyrazolidium salt, pyrrolidinium salt, pyridinium salt can be used.

  Examples of the 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 electrolyte functioning as an organic hole transport agent include triphenyldiamine (TPD1, TPD2, TPD3), OMeTAD, and the like.

<First transparent conductive layer>
The first transparent conductive layer 15 is preferably a tin-doped indium oxide film (ITO film) or an impurity-doped indium oxide film (In ₂ O ₃ film) produced by a low temperature growth sputtering method or a low temperature spray pyrolysis method. In addition, an impurity-doped zinc oxide film (ZnO film) manufactured by a solution growth method may be used, and these may be stacked and used. Alternatively, a fluorine-doped tin dioxide film (SnO ₂ : F film) formed by a thermal CVD method may be used. In addition, an impurity-doped indium oxide film (In ₂ O ₃ film) or the like can be used. As other film forming methods, there are a vacuum deposition method, an ion plating method, a dip coating method, a sol-gel method, and the like. The formation of surface irregularities in the order of the wavelength of incident light by the growth of these films is still preferable because of the light confinement effect. The first transparent conductive layer may be a thin metal film such as Au, Pd, or Al formed by a vacuum deposition method or a sputtering method.

<Thin film photoelectric conversion layer>
The thin film photoelectric conversion layer 16 is preferably a pin junction hydrogenated amorphous silicon semiconductor film continuously deposited by plasma CVD. Although the pin junction is provided with the p-type semiconductor film on the first translucent conductive film side, it may be a reverse junction nip junction. Here, the one-conductivity-type silicon-based semiconductor layer 16a and the reverse-conductivity-type silicon-based semiconductor layer 16c mean a p-type semiconductor and an n-type semiconductor, or an n-type semiconductor and a p-type semiconductor, respectively. The silicon-based semiconductor layer 16b that is substantially intrinsic means an i-type semiconductor.

Here, as long as the i-type semiconductor film is amorphous, at least one of the p-type semiconductor film and the n-type semiconductor film may have microcrystals, or a hydrogenated amorphous silicon alloy film. For example, hydrogenated amorphous silicon carbide is more preferable for the p-film on the light incident side because it increases translucency and reduces light penetration loss. Other deposition methods such as catalytic CVD may be used. When plasma CVD and catalytic CVD are combined, photodegradation can be suppressed and reliability can be improved. These silicon-based semiconductor layers 16a, 16b, and 16c are good because they can be continuously deposited under the respective film-forming conditions by chemical vapor deposition.

More specifically, for example, in the case of a p-type a-Si: H film, SiH ₄ , H ₂ gas, and B ₂ H ₆ (diluted to 500 ppm with H ₂ ) are used as source gases, and the flow rates of these gases The film thickness is in the range of 50 mm to 200 mm, preferably 80 mm to 120 mm. If it is thin, an internal electric field cannot be formed, and if it is thick, the light loss increases. Subsequently, SiH ₄ and H ₂ gases are used as the i-type a-Si: H source gas, the flow rates of these gases are optimized, and the film thickness is 500 to 5000 mm.
The range of Å (0.05 μm to 0.5 μm) is good, preferably 1500 Å to 2500 Å (0.15 μm to 0.25 μm)
) Because, if it is thin, sufficient photocurrent cannot be obtained, and if it is thick, light cannot be transmitted to the subsequent dye-sensitized photoelectric conversion device. Subsequently, in the case of an n-type a-Si: H film, SiH ₄ , H ₂ gas, and PH ₃ (diluted to 1000 ppm with H ₂ ) are used as source gases, and the flow rates of these gases are optimized, respectively. Is preferably in the range of 50 mm to 200 mm, preferably 80 mm to 120 mm. If it is thin, an internal electric field cannot be formed, and if it is thick, light loss increases. The substrate temperature is in the range of 150 ° C. to 300 ° C. for any pin film, preferably 180 ° C. to 240 ° C., and an optical semiconductor that may be low or high cannot be obtained.

<Second transparent conductive layer>
As the second transparent conductive layer 17, as with the first transparent conductive layer 15, a tin-doped indium oxide film (ITO film) or impurity-doped indium oxide film produced by a low temperature growth sputtering method or a low temperature spray pyrolysis method. (In ₂ O ₃ film) is preferable. In addition, an impurity-doped zinc oxide film (ZnO film) manufactured by a solution growth method may be used, and these may be stacked and used. Alternatively, a fluorine-doped tin dioxide film (SnO ₂ : F film) formed by a thermal CVD method may be used. In addition, an impurity-doped indium oxide film (In ₂ O ₃ film) or the like can be used. Other film forming methods include a vacuum deposition method, an ion plating method, a dip coating method, and a sol-gel method. The formation of surface irregularities in the order of the wavelength of incident light by the growth of these films is still preferable because of the light confinement effect. The second transparent conductive layer may be a thin metal film such as Au, Pd, or Al formed by a vacuum deposition method or a sputtering method.

<Translucent covering>
As the translucent covering 18, a fluorine resin, a silicon polyester resin, a high weather resistance polyester resin, a polyvinyl chloride resin, a coating resin used for a metal roof, etc. are particularly excellent in weather resistance. The translucent covering has a thickness of 0.1 μm to 6 mm, preferably 1 μm to 4 mm. In addition, antiglare, heat shield, heat resistance, low contamination, antibacterial, antifungal, design, high workability, scratch resistance / wear resistance, snow sliding, antistatic, far infrared radiation, acid resistance Reliability and merchantability can be further improved by providing the translucent covering with properties, corrosion resistance, environmental compatibility, and the like.

In the case of the photoelectric conversion device of FIG. 2, a thin film photoelectric converter may be formed in advance as long as the translucent covering 18 has a sufficient mechanical strength and can be used as a support. In this case, the thickness of the translucent covering is 0.1 mm to 0.6 mm, preferably 1 mm to 4 mm. Besides the above materials, resins such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyimide, polycarbonate, etc. Sheets, white plate glass, soda glass, borosilicate glass, inorganic sheets such as ceramics, and organic-inorganic hybrid sheets are preferable.

  Further, the light incident side surface of the translucent covering 18 may be flat on both sides, but the surface having irregularities in the order of the wavelength of incident light may have a light confinement effect.

<Underlayer>
Although the underlayer is not shown, in the photoelectric conversion device of FIGS. 1 to 4 , the thin dense single-conductive transporter between the conductive substrate 11 and the single-conductive transporter 12 is porous. When the layer is inserted, no reverse current flows.

<Catalyst layer>
Although the catalyst layer is not shown, in the configurations of FIGS. 1 to 4 , an ultrathin film such as platinum or carbon is inserted between the first transparent conductive layer 15 and the reverse porous and reverse conductivity type transporter 14. Then, since the movement of holes is improved, the condition is good.

Thus, according to the photoelectric conversion device of the present invention, by mixing or laminating a dye monomer having a porphyrin skeleton and an aggregate and using it as a photoelectric conversion material, it has long wavelength sensitivity and has a light absorption wavelength width. And the photoelectric conversion efficiency can be improved.

Further, when such a photoelectric conversion device of the present invention is applied to the stacked photoelectric conversion device of FIG. 2 , the pigment has a dye on the main surface of the conductive substrate on which light is incident from the main surface side. A dye-sensitized photoelectric converter that performs photoelectric conversion by a sensitizing action of a dye and a thin-film photoelectric converter having a semiconductor layer that performs photoelectric conversion are stacked in this order, and short-wavelength light is emitted from the thin-film photoelectric converter. The dye-sensitized photoelectric converter that absorbs light that has been well photoelectrically converted and that has passed through the thin-film photoelectric converter and performs photoelectric conversion by the sensitizing action of the dye absorbs, so conversion that combines the conversion efficiency of both photoelectric converters Efficiency is obtained.

  In addition, since each of the thin-film photoelectric conversion body and the dye-sensitized photoelectric conversion body can be produced by a low-temperature process, it can be easily and easily manufactured at a lower cost than a conventional solar cell even if it has a laminated structure. Furthermore, a thin-film photoelectric converter is arranged on the light incident side, and a dye-sensitized photoelectric converter is arranged on the rear side, so that the rear dye-sensitized photoelectric converter directly emits strong light such as sunlight. I will not receive it. Moreover, the thin film photoelectric conversion body on the light incident side better absorbs short wavelength light and almost transmits long wavelength light. Therefore, the dye-sensitized photoelectric converter placed on the rear side does not directly receive strong light such as sunlight, and since there is no ultraviolet light and the short wavelength light is drastically reduced, the light deterioration of the dye is greatly reduced and eliminated. it can. In addition, it does not receive strong light directly, and the temperature increase can be suppressed by cooling the dye-sensitized photoelectric conversion body easily from the other main surface side (back surface of the substrate) of the conductive substrate on the back side. Thermal degradation can be suppressed.

As described above, as a photoelectric conversion device of the present invention, a metal oxide having a porphyrin skeleton having a porphyrin skeleton and an associated substance mixed and adsorbed or laminated on a conductive support is mixed. Although the example which arrange | positioned the physical semiconductor in the state which exists in electrolyte was demonstrated, it is not limited to this. For example, a Schottky junction thin film solar cell in which a transparent conductive layer, a layer containing a dye monomer having a porphyrin skeleton and an aggregate , and a conductive layer made of metal or the like are sequentially stacked on a substrate can be provided. .

It is also possible to form a thin-film solar cell in which a conductive layer such as a metal, a layer containing a dye monomer having a porphyrin skeleton and an aggregate , an inorganic or organic semiconductor layer, and a transparent conductive layer are sequentially laminated on a substrate. If the monomer and the aggregate of the dye having a porphyrin skeleton are used as the photoelectric conversion material, it can be implemented as the photoelectric conversion device of the present invention.

  Moreover, the photoelectric conversion apparatus of this invention is not limited to a solar cell, What is necessary is just to have a photoelectric conversion function, and it can apply also to various light receiving elements, an optical sensor, etc.

  The photoelectric conversion device described above can be used as a power generation unit, and a photovoltaic power generation device configured to supply the generated power from the power generation unit to a load can be obtained.

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

  Examples of the present invention will be described below.

First, a fluorine-doped tin oxide glass substrate with a transparent conductive film was used as a conductive substrate, and porous titanium dioxide was formed thereon. In the production method of titanium dioxide, which is an electron transporter, first, acetylacetone was added to TiO ₂ anatase powder, and then kneaded with deionized water to prepare a titanium oxide paste stabilized with a surfactant. The prepared paste was applied at a constant speed onto a titanium substrate by the doctor blade method, and 450 ° C in the air.
Baked for 30 minutes.

Tetracarboxyphenylporphyrin is used as the dye, ethanol is used as the solvent used to dissolve the dye, and a conductive support in which a porous titanium dioxide layer is formed is dissolved in a solution (0.3 mmol) of the dye. / L) for 12 hours to support the dye monomer on the porous titanium dioxide layer.

  Thereafter, the substrate was washed with ethanol and dried.

FIG. 6 shows an absorption spectrum of a conductive substrate provided with a porous titanium dioxide layer adsorbed with this dye monomer. Although not shown, it was observed absorption by Q-band 'corresponding to S ₁ transitions to the absorption and near 500~700nm by Soret-band' corresponding to S ₂ transition of the dye monomer around 450nm.

Then, as an acid treatment, a dye-adsorbed substrate in a 0.1 mol / l nitric acid aqueous solution was immersed for 12 hours and then dried to form a dye aggregate (J aggregate) on the porous titanium dioxide layer. .

Further, FIG. 6 shows an absorption spectrum of a conductive substrate provided with a porous titanium dioxide layer on which a dye aggregate is adsorbed. The absorption spectrum was measured using a V-570 absorbance measuring apparatus manufactured by JASCO Corporation, and the analysis conditions were a spectral bandwidth of 2.0 nm and a wavelength scanning speed of 400 nm / min. As a result, less absorption by Q-band 'corresponding to S ₁ transitions observed at about the absorption and 600~800nm by Soret-band' corresponding to S ₂ transitions aggregate of dye 520 nm, 500n
It was found that the long wavelength sensitivity of m or more was improved.

  FIG. 7 shows an absorption spectrum when the dye monomer and the dye aggregate are laminated. As is clear from FIG. 7, it was found that the absorption sensitivity is good on the long wavelength side (400 to 550 nm and 600 to 800 nm).

As a hole-transporting layer (electrolyte), LiI of 0.1 mol / l, the solution was prepared by stirring until dissolution is electrolyte put I ₂ propyl carbonate 0.05 mol / l.

As the counter electrode, a glass substrate with a transparent conductive film of fluorine-doped tin oxide in which Pt was deposited by sputtering to a thickness of 50 nm was used.

  The substrate on which the aggregate of the dye is adsorbed and the counter electrode substrate are made to face each other using a thermoplastic resin such as high-milan as a spacer, an electrolytic solution is injected from the opening, and sealed with a thermoplastic resin or a reactive resin. A cell of a photoelectric conversion device was formed.

  The spectral sensitivity of the photoelectric conversion device thus obtained was higher in the spectral association of 700 to 800 nm in the dye aggregate than in the dye monomer, and the conversion efficiency on the long wavelength side could be improved.

  As described above, also in this example, the photoelectric conversion device of the present invention can be easily and easily manufactured, and high photoelectric conversion efficiency can be realized.

It is sectional drawing which shows typically an example of the photoelectric conversion apparatus as a reference . It is sectional drawing which shows typically the other example of the photoelectric conversion apparatus as a reference . It is sectional drawing which shows the other example of the photoelectric conversion apparatus of this invention typically. It is sectional drawing which shows the other example of the photoelectric conversion apparatus of this invention typically. It is a molecular formula explaining a porphyrin skeleton. It is a characteristic view explaining an absorption spectrum. It is a characteristic view explaining an absorption spectrum.

1: Photoelectric conversion device
11: Conductive substrate (conductive support)
12: Electron transporter (metal oxide semiconductor)
13: Dye
14: Electrolyte
15: First transparent conductive layer
16: Non-single crystal photoelectric conversion layer
17: Second transparent conductive layer
18: Translucent coating

Claims (3)

A photoelectric conversion device comprising a pigment monomer having a porphyrin skeleton and an aggregate mixed or laminated and used as a photoelectric conversion material. A metal oxide semiconductor in which a monomer and an aggregate of a dye having a porphyrin skeleton and photoelectric conversion are mixed and adsorbed or laminated on a conductive support is disposed in an electrolyte. A photoelectric conversion device characterized by that. A photovoltaic device comprising the photoelectric conversion device according to claim 1 or 2 as a power generation means, and the power generated by the power generation means is supplied to a load.

Images