JP4637473B2 - Stacked photoelectric conversion device - Google Patents

Description

  The present invention relates to a stacked photoelectric conversion device that can be expected to have high photoelectric conversion efficiency, is excellent in weather resistance, and can be reduced in cost.

Bulk-type crystalline silicon solar cells are rapidly expanding the market due to their excellent weather resistance and durability of more than 20 years. In this bulk-type crystalline silicon solar cell, a pn semiconductor junction is formed on a thick silicon semiconductor substrate (about 300 μm) made of a high-purity single material to perform photoelectric conversion. Although sunlight and visible light have a wide wavelength spectrum, there is a wavelength limitation on light energy absorption and power generation due to the band gap of the semiconductor, and a photoelectric conversion device made of a single material has a limit in photoelectric conversion efficiency. In addition, a thick silicon substrate has a high material cost. For this reason, the production cost of less than half the current cost is eagerly desired for the spread of solar cells to ordinary households.

In addition, a thin-film amorphous silicon solar cell can be produced at a low cost by using a thin silicon film (about 0.3 μm). Moreover, the problem of light degradation is being solved. However, the market has not expanded due to low conversion efficiency.

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 in a thin film is known. Even with the same silicon, amorphous and microcrystals have different band gaps, so by stacking these two photoelectric conversion devices, the conversion efficiency has been increased by covering the solar spectrum more widely. Being started. In this stacked thin-film silicon solar cell, the amorphous silicon photoelectric conversion device is as thin as about 0.2 μm, but the microcrystalline silicon photoelectric conversion device is as thick as about 2 μm. Therefore, since the manufacturing cost of the microcrystalline silicon photoelectric conversion device is much higher than that of the thin film amorphous silicon solar cell, the market has not been rapidly expanded.

  In addition, since dye-sensitized solar cells do not require high-temperature treatment or vacuum equipment, they are considered to be advantageous for cost reduction, and research and development have been promoted rapidly in recent years. This dye-sensitized solar cell is an electrode in which a single molecule of an organic dye is adsorbed on the particle surface of a porous titanium oxide layer obtained by sintering fine particles having a particle size of several tens of nanometers built on a conductive glass substrate. Is used as a light working electrode, and an electrolyte solution containing an iodine / iodide redox pair is filled between a conductive glass counter electrode sputtered with platinum, and this electrolyte solution is sealed. By making such a porous structure, the surface area of the photoactive electrode is increased more than 1000 times, and light absorption by the adsorbing dye is efficiently performed. Photoelectric conversion of about 10% at the research level and around 7% at the reproduction level. Efficiency is known. For this reason, further improvement in photoelectric conversion efficiency is required for market introduction.

  Methods for improving the conversion efficiency of dye-sensitized solar cells include improving the conductivity of porous oxide semiconductors and increasing the sensitizing ability of dyes (such as increasing the spectral sensitivity and increasing the wavelength) ) Has been studied. Among these, as a method for improving the conductivity of the oxide semiconductor, the shape of the oxide semiconductor is made into a needle shape or a nanotube. Research has been done. Moreover, since the dye-sensitized solar cell carries the dye on titanium dioxide or the like, there is a concern that the dye may be photodegraded by ultraviolet rays or short wavelength light. For this reason, it is considered to put it into practical use as a power source for personal computers and mobile phones for indoor use. Under strong sunlight, it is considered to insert a UV absorbing film on the light incident side to suppress the photodegradation of the dye. It is still a question, and insertion of an ultraviolet absorbing film or the like causes absorption of visible light, resulting in a decrease in photoelectric conversion efficiency.

Here, a conventional example of a composite solar cell in which the photoelectric conversion efficiency of the dye-sensitized solar cell is improved will be described. According to the composite solar cell disclosed in Patent Document 1, a dye-sensitized solar cell is disposed on the side facing the sunlight, and a crystalline silicon solar cell is disposed on the rear side of the dye-sensitized solar cell. Thus, a composite solar cell is formed. In dye-sensitized solar cells using a ruthenium complex, sunlight having a wavelength of 600 nm or less can be effectively used. In addition to ruthenium complexes, xanthene dyes can be used as the dye. As a solar cell that generates power with sunlight having a wavelength of 600 nm or more, attention is paid to a crystalline silicon solar cell using single crystal silicon and polycrystalline silicon, which forms a band gradient by the pn junction of silicon, Among them, electrons and holes generated by light having a wavelength of 400 nm to 1100 nm are separated by an internal electric field, and an electromotive force is generated. That is, in this conventional composite solar cell, a dye-sensitized solar cell using a ruthenium complex is arranged on the side facing the sunlight, and power is generated with light having a wavelength of 300 nm to 600 nm. A crystalline silicon solar cell is arranged on the back side of the dye-sensitized solar cell, and the wavelength of the light transmitted through the dye-sensitized solar cell is 400
The power generation is performed at nm to 1100 nm.
JP 2002-231324 A

Bulk type crystalline silicon solar cells have a problem of resources and material cost because the silicon thickness is about 300 μm. In addition, a high temperature treatment of 1000 ° C. or higher is required for crystallization, and the process cost is high. In addition, since there is a limit to the substrate size (approximately 15 cm square) that is a power generation cell, the assembly cost required for modularization (meter size) from the power generation cell is increased.

The thin film amorphous silicon solar cell can solve almost all of the above problems by providing a thin silicon film (about 0.3 μm), a low temperature process (about 300 ° C.), and a substrate having a large free size. However, since amorphous silicon has a large band gap, it can absorb only short-wavelength light of about 700 nm or less, and thus has a problem of low photoelectric conversion efficiency.

  Laminated thin-film silicon solar cells have a structure in which amorphous silicon photoelectric conversion devices and microcrystalline silicon photoelectric conversion devices are stacked in order to increase conversion efficiency. It has been. However, in actuality, the film thickness of the microcrystalline silicon photoelectric conversion device is about 10 times that of the amorphous silicon photoelectric conversion device, and these manufacturing apparatuses use almost the same expensive large-scale vacuum equipment (such as PCVD). In addition, since the manufacturing cost of the microcrystalline silicon photoelectric conversion device tends to be proportional to the film thickness as compared with the amorphous silicon photoelectric conversion device, there is a problem that the cost cannot be reduced.

  The dye-sensitized solar cell is considered to be a solar cell that can be manufactured at the lowest cost because it does not require a 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. In addition, in dye-sensitized solar cells, there is a concern that photodegradation of the dye may occur due to ultraviolet light or short wavelength light. Moreover, 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. In this way, the dye-sensitized solar cell has a problem in weather resistance since the fears of light deterioration and heat deterioration of the dye have not yet been solved.

In the conventional example of the composite type solar cell in which the photoelectric conversion efficiency of the dye-sensitized solar cell is improved, the dye-sensitized solar cell is arranged on the side facing the sunlight, and the dye-sensitized solar cell is disposed after the dye-sensitized solar cell. A crystalline silicon solar cell is arranged on the side to form a composite solar cell. In this composite solar cell, the dye-sensitized solar cell is arranged on the side facing the sunlight, and as described above, the fear of light deterioration and heat deterioration of the dye has not been solved yet, and the problem of weather resistance Is still held. Furthermore, a bulk type crystalline silicon solar cell as described above is arranged behind the light incident side to obtain high photoelectric conversion efficiency. However, as described above, the bulk-type crystalline silicon solar cell has a problem of resources and material cost because the thickness of silicon is about 300 μm. Also,
Crystallization requires a high-temperature treatment of 1000 ° C. or higher, and the process cost is high. In addition, there is a limit to the size of the substrate that is the power generation cell, and the assembly cost required for modularization from the power generation cell is increased.

  The present invention has been made in view of such circumstances, and has an excellent stacked photoelectric conversion device that can improve conversion efficiency, reduce costs, and greatly reduce and eliminate the problem of weather resistance (light deterioration and heat deterioration). Is intended to provide.

In order to achieve the above object, the stacked photoelectric conversion device according to the present invention includes: 1) the first main surface of the translucent substrate on which light is incident from the first main surface side; The transparent conductive layer, the non-single crystal photoelectric conversion layer, the second transparent conductive layer, the catalyst layer, the hole transporter, the dye, and the electron transporter are arranged in this order. Features.

  2) In the above 1), the peak wavelength of the spectral sensitivity of the dye is longer than the peak wavelength of the spectral sensitivity of the non-single-crystal photoelectric conversion layer.

  3) In the above 1), the non-single-crystal photoelectric conversion layer has a pin structure including an i-type amorphous silicon layer.

  The stacked photoelectric conversion device of the present invention includes a thin film photoelectric converter having a first transparent conductive layer, a non-single-crystal photoelectric conversion layer, a second transparent conductive layer, and a catalyst layer, and light transmitted through the thin film photoelectric converter. Since a dye-sensitized photoelectric converter that has a dye that absorbs light and performs photoelectric conversion by the sensitizing action of the dye is laminated in this order, short-wavelength light is often photoelectrically converted by the thin-film photoelectric converter. In the dye-sensitized photoelectric conversion body, long wavelength light (including transmitted short wavelength light) is often photoelectrically converted, and conversion efficiency combining the conversion efficiency of both photoelectric conversion bodies 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, strong light is not directly received, and the temperature increase can be suppressed by cooling the dye-sensitized photoelectric conversion body easily from the back side, and thermal deterioration of the dye can be suppressed.

  In addition, the stacked photoelectric conversion device of the present invention is capable of emitting light in different wavelength ranges because the peak wavelength of the spectral sensitivity of the dye is longer than the spectral sensitivity peak wavelength of the semiconductor layer of the thin film photoelectric converter. Photoelectric conversion is possible, and high photoelectric conversion efficiency is obtained.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. A schematic cross-sectional view of the stacked photoelectric conversion device of the present invention is shown in FIG . FIG . 2 is a schematic cross-sectional view of a stacked photoelectric conversion device as a reference . The arrow in the figure indicates the light incident side. Also, the difference between FIG. 1 and FIG. 2 is that the configuration of the porous one-conducting transporter 15 and the reverse porous and reverse-conducting transporter 17 formed so as to fill the porous is different from the light incident direction. This is the opposite direction.

  According to one embodiment shown in FIGS. 1 and 2, a non-single-crystal semiconductor that is produced by thin film formation and photoelectric conversion is performed on the other main surface of a light-transmitting substrate on which light is incident from one main surface side. Non-single crystal photoelectric conversion device 2 which is a thin film photoelectric conversion body having a layer, a dye having a peak sensitivity on a longer wavelength side than this non-single crystal photoelectric conversion device and absorbing light transmitted through non-single crystal photoelectric conversion device 2 The dye-sensitized photoelectric conversion device 3 which is a dye-sensitized photoelectric conversion body that performs photoelectric conversion by the sensitizing action of is laminated.

The non-single-crystal photoelectric conversion device 2 includes a first transparent conductive layer 12, a non-single-crystal photoelectric conversion layer 13, and a second transparent conductive layer 14 that are sequentially formed on a translucent substrate 11. The non-single-crystal photoelectric conversion layer 13 may be a silicon-based non-single-crystal thin film pin junction layer or a compound semiconductor-based 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. Silicon-based non-single crystals include amorphous silicon, amorphous silicon including nano-sized crystals, and microcrystalline silicon. Especially, amorphous silicon with short-wavelength sensitivity and nano-sized crystals with reduced light degradation can be used. Including amorphous silicon is preferable. Here, the amorphous silicon system includes alloy systems such as amorphous silicon carbide and amorphous silicon nitride.

The dye-sensitized photoelectric conversion device 3 is formed on the second transparent conductive layer 14, and includes a porous electron transporter 15, an inverse porous hole transporter 17 formed so as to fill the porous, It consists of a conductive sheet 18 and a structure in which a dye 16 is disposed at the interface between the two transporters.

The first output from the non-single crystal photoelectric conversion layer 2 and the second output from the dye-sensitized photoelectric conversion device 3 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 second 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.

FIG. 3 is a schematic cross-sectional view of a stacked photoelectric conversion device as a reference showing the non-single crystal photoelectric conversion layer 2 in FIG. 2 in more detail. In the structure shown in FIG. 3, a first transparent conductive layer 12, a one-conductivity-type silicon-based semiconductor layer 13a, and a substantially intrinsic amorphous silicon-based layer are sequentially formed on a transparent substrate 11 on which light is incident. Semiconductor layer 13b, reverse conductivity type silicon-based semiconductor layer 13c, second transparent conductive layer 14, porous electron transporter 15, reverse porous hole transporter 17 formed so as to fill this porous, conductive The sheet 18 is laminated, and a dye 16 (having a peak sensitivity on a longer wavelength side than the amorphous silicon semiconductor) is arranged at the interface between the two transporters.

<Translucent substrate>
As the light-transmitting substrate 11, white plate glass with few iron components is the best because of its high transmittance and mechanical strength. In addition, a transparent inorganic substrate such as blue plate glass, borosilicate glass, soda glass, ceramic, sapphire, or a transparent organic resin substrate such as polycarbonate may be used. The translucent 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. The thickness of the translucent substrate is preferably 0.05 mm to 6 mm depending on the material, the size of the substrate, and the use, and is preferably 3 mm to 4 mm in terms of strength and weight if it is used for roofing of glass and metric size.

<First Transparent Conductive Layer> As the first transparent conductive layer 12, a fluorine-doped tin dioxide film (SnO ₂ : F film) produced by a thermal CVD method or a spray pyrolysis method has the lowest cost and the lowest sheet resistance. Good. In addition, a tin-doped indium oxide film (ITO film) produced by a sputtering method, an impurity-doped zinc oxide film (ZnO film) produced by a solution growth method, or the like may be used, or these may be laminated. . 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. In addition, an impurity-doped indium oxide film (In ₂ O ₃ film) or the like can be used. Further, it can be formed by a dip coating method, a sol-gel method, a vacuum deposition method, an ion plating method, or the like.

<Non-single crystal photoelectric conversion layer>
As the non-single-crystal photoelectric conversion layer 13, a pin-junction hydrogenated amorphous silicon-based semiconductor film continuously deposited by a plasma CVD method is preferable . In here, the one conductivity type silicon-based semiconductor layer 13a and the opposite conductivity type silicon-based semiconductor layer 13c refers to p-type semiconductor and the n-type semiconductor or an n-type semiconductor and the p-type semiconductor, respectively. The substantially intrinsic amorphous silicon-based semiconductor layer 13b 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 be microcrystalline. Also, a hydrogenated amorphous silicon alloy film may be used. 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 13a, 13b, and 13c 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 14, a tin-doped indium oxide film (ITO film) produced by a low temperature growth sputtering method or a low temperature spray pyrolysis method is preferable. In addition, an impurity-doped zinc oxide film (ZnO film) manufactured by a solution growth method, a fluorine-doped tin dioxide film (SnO ₂ : F film) formed by a thermal CVD method, or the like is preferable. 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.

<Porous electron transporter>
As the porous electron transporter 15, an n- type metal oxide semiconductor such as porous titanium dioxide is particularly preferable.

In the case of FIG. 1, the porous electron transporter 15 is formed on the conductive sheet 18, but in the case of FIG. 2, it is formed on the second transparent conductive layer 14.

  The electron transporter 15 is usually made of an n-type metal oxide semiconductor, and is preferably composed of a plurality of granular or linear bodies (needle-like bodies, tube-like bodies, columnar bodies, etc.).

  By making the electron transporter 15 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.

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. An oxide semiconductor composed of at least one of the above metal elements is preferable, and nitrogen (N), carbon (C), fluorine (F), sulfur (S), chlorine (Cl
), One or more non-metallic elements such as phosphorus (P) 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 composed of fine particles or fine lines, and the average particle diameter or average wire diameter is 5 nm to 500 nm. More preferably, the thickness is 10 nm to 200 nm. Here, if the average wire diameter is less than 5 nm to 500 nm, the material cannot be refined if the lower limit is less than this, and if the upper limit is more than this, 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 sheet as shown in FIG.

  As shown in FIG. 2, in the case of forming directly on the second transparent conductive layer, the low temperature growth method is advantageous because it does not adversely affect the non-single crystal photoelectric conversion device.

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 a microwave treatment, a CVD / UV treatment, or the like is preferable as a post treatment. As a material of the metal oxide semiconductor, porous ZnO by an electrodeposition method, porous TiO ₂ by an electrophoretic electrodeposition method, or the like is preferable.

<Dye>
The dye 16 may be any dye having a characteristic that the photocurrent efficiency (IPC) so-called sensitivity with respect to incident light is longer than the absorption limit wavelength of the non-single crystal photoelectric conversion device 2. It is valid. In addition, any dye having the characteristic of extending to a longer wavelength side than the substantially intrinsic amorphous silicon semiconductor 13b is effective.

The absorption limit wavelength of a substantially intrinsic amorphous silicon-based semiconductor is about 700 nm. In this case, any dye that exhibits IPCE above about 700 nm is effective. Therefore, preferably, a dye having a long wavelength sensitivity as much as possible, a dye having a peak sensitivity longer than the peak sensitivity of the non-single-crystal photoelectric conversion device 2, and the peak sensitivity of the substantially intrinsic amorphous silicon semiconductor. A dye having a peak sensitivity on the longer wavelength side and a dye having a peak sensitivity on the longer wavelength side than the absorption limit wavelength of about 700 nm of the substantially intrinsic amorphous silicon semiconductor are effective. As such a dye, bis-type squarylium cyanine dye has an IPCE peak wavelength of 800
It is near nm and effective. In addition, azurenium salt compounds, squalinic acid derivatives, triallylpyrazoline, hydrazone derivatives, biphenyldiamine derivatives, tri-p-tolylamine (TPTA), trisazo pigments, τ-type non-metals having high sensitivity (IPCE) at wavelengths of 700 nm or more Dyes such as phthalocyanine, titanyl phthalocyanine, squarylium cyanine, black dye, coumarin, β-diketonate, Re complex, Os complex, Ni complex, Pd complex, and Pt complex are effective.

  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, 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.

As other examples of color materials, in addition to metal complex dyes, organic dyes and organic pigments, inorganic dyes, inorganic pigments, inorganic semiconductors, etc. may be used, and the shape of the dye may be molecules, ultrathin films, fine particles, ultrafine particles, It may consist of at least one kind of quantum dot. In particular, in the case of ultrafine particle semiconductors, the band gap is no longer a value specific to the material, but depends on the size. Even with a material with a very small band gap (1 eV or less), the band gap can be increased by nano-sizing, so the absorption wavelength Can be selected and it is easy to increase the wavelength of sensitivity. CdS, Cd as ultrafine particle semiconductors
Examples include Se, PbS, PbSe, CdTe, Bi ₂ S ₃ , InP, Si, and the like.

< Hole transporter>
As the reverse porous hole transporter 17, a hole transporter such as a gel electrolyte (p-type semiconductor, liquid electrolyte, solid electrolyte, electrolytic salt, etc.) is particularly preferable. The reverse porous body is formed so as to fill the porous body, and the electrolytic solution exhibits the best carrier movement, but gelation and solidification are preferred because of problems such as liquid leakage.

  In the case of FIG. 1, the non-single crystal photoelectric conversion device 2 and the porous metal oxide semiconductor 15 supporting the dye 16 on the conductive sheet 18 are laminated. In the case of FIG. The transparent conductive layer 14 and the porous metal oxide semiconductor 15 supporting the dye 16 are directly formed.

Examples of the material for the hole transport layer 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. As compound semiconductors suitable for the present invention, CuI, CuInSe ₂ , Cu ₂ O, CuSCN, CuS, CuInS ₂ , CuAlSe _{2 and the} like are preferable, and among these, CuI and CuSCN are preferable, 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, one 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. As a gel electrolyte, acetonitrile, ethylene carbonate, propylene carbonate, or a mixture thereof was mixed with a host polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polyacrylic acid, polyacrylamide, and polymerized. A gel 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 sulfoimidazolium salt, tetracyanoquinodimethane salt or 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 organic hole transporting agent include triphenyldiamine (TPD1, TPD2, TPD3) and OMeTAD.

<Conductive sheet>
In the case of FIGS. 1 and 2, the conductive sheet 18 may be a thin metal sheet alone, such as titanium, stainless steel, aluminum, silver, or copper. A resin sheet impregnated with fine particles or fine wires of carbon or metal is preferable. Also, a thin metal film such as titanium, stainless steel, aluminum, silver, copper, transparent conductive film ITO, SnO ₂ : F, ZnO: Al, etc., laminated Ti / ITO / Ti conductive film 18b with conductive film 18b, etc. are preferable. . As the insulating sheet 18a, resin sheets such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), polyimide, and polycarbonate, inorganic sheets such as soda glass, borosilicate glass, and ceramics, and organic-inorganic hybrid sheets are preferable.

  If the conductive sheet 18 has light reflectivity, the transmitted light can be reflected and reused. In the case of a metal sheet, silver or aluminum is preferable. Further, in the case of the conductive film 18b, silver (Ag), a Ti / Ag / Ti laminated film with an adhesion layer, etc. are preferable, and it is formed by a vacuum deposition method, an ion plating method, a sputtering method, an electrolytic deposition method, or the like. Good. The thickness of the conductive sheet is 0.01 mm to 5 mm, preferably 0.01 mm to 0.5 mm.

<Underlayer>
Although not shown as an underlayer, in the case of FIG. 1, if a thin dense layer of a porous electron transporter is inserted between the conductive sheet 18 and the porous electron transporter 15, no reverse current flows. Good.

In the case of FIG. 2, although not shown, if a thin dense layer of a porous electron transporter is inserted between the second transparent conductive layer 14 and the porous electron transporter 15, the reverse current does not flow. Good.

<Catalyst layer>
Although not shown as a catalyst layer, in the case of FIG. 1, when an ultrathin film such as platinum or carbon is inserted between the second transparent conductive layer 14 and the reverse porous and hole transporter 17, the movement of holes Is in good condition.

In the case of FIG. 2, although not shown, if an ultrathin film such as platinum or carbon is inserted between the conductive sheet 18 and the reverse porous and hole transporter 17, the movement of holes is good.

  A collector electrode may be provided on the first transparent conductive layer, the second transparent conductive layer, and the conductive sheet to reduce the electrical resistance.

  Thus, the stacked photoelectric conversion device of the present invention has a thin film photoelectric conversion body having a non-single-crystal semiconductor layer for performing photoelectric conversion on a light-transmitting substrate on which light is incident, and light transmitted through the semiconductor layer. Since the dye-sensitized photoelectric converter that performs photoelectric conversion by the sensitizing action of the absorbing dye is laminated in this order, short-wavelength light is often photoelectrically converted by the thin-film photoelectric converter, and the dye-sensitized photoelectric converter Long wavelength light (including transmitted short wavelength light) is often photoelectrically converted by the converter, and conversion efficiency combining the conversion efficiencies of both photoelectric converters 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 do 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, strong light is not directly received, and the temperature increase can be suppressed by cooling the dye-sensitized photoelectric conversion body easily from the back side, and thermal deterioration of the dye can be suppressed.

  In addition, the stacked photoelectric conversion device of the present invention is capable of emitting light in different wavelength ranges because the peak wavelength of the spectral sensitivity of the dye is longer than the spectral sensitivity peak wavelength of the semiconductor layer of the thin film photoelectric converter. Photoelectric conversion is possible, and high photoelectric conversion efficiency is obtained.

The stacked photoelectric conversion device of the present invention, when Ru an amorphous silicon-based semiconductor which is substantive intrinsic absorbs and generator short wavelength light of less than about 700nm, more than about 700nm long-wavelength light Therefore, light in a sufficient wavelength region can be transmitted to the rear side and can be used for power generation. The wavelength range of sunlight is 310 nm to 2000 nm, and the wavelength range with high intensity is 400 nm to 1200 nm. Therefore, sufficient photoelectric conversion efficiency can be obtained by using a dye having sensitivity at 700 nm to 1200 nm or 700 nm to 2000 nm in the dye sensitized photoelectric conversion device on the rear side. For this reason, it is preferable that the dye has sensitivity in a sufficiently wide wavelength range, but it is preferable that the peak wavelength of spectral sensitivity is on the longer wavelength side than at least the non-single crystal thin film.

In addition, the multilayer photoelectric conversion device of the present invention is effective in using a dye-sensitized photoelectric converter for long-wavelength light that has passed through a thin film photoelectric converter because the peak wavelength of the spectral sensitivity of the dye is 700 nm or more. Can be photoelectrically converted.

In the stacked photoelectric conversion device of the present invention, the color material of the dye-sensitized photoelectric conversion body is composed of at least one of a metal complex dye, an organic dye, an inorganic dye, an organic pigment, an inorganic pigment, and an inorganic semiconductor, and When the shape of the dye is at least one of molecules, ultrathin films, fine particles, ultrafine particles, and quantum dots, long wavelength light that has passed through the thin film photoelectric converter can be well photoelectrically converted. In addition, since the shape of the dye becomes ultrafine particles and quantum dots, a semiconductor material having a smaller band gap can be used, and the selectivity of the material is improved.

Hereinafter, examples showing the present invention more specifically will be described. On a glass substrate (size 1 cm × 2 cm) with a transparent conductive film (SnO ₂ : F, sheet resistance 10 Ω / □), a p-type a-Si: H film and an i-type a-Si: H are first formed by a plasma CVD apparatus. A film and an n-type a-Si: H film were successively deposited in vacuum.

p-type a-Si: 500pp as the source gas of H film _SiH 4, _{H 2 gas,} with B ₂ H 6 _{(H 2}
1), and the flow rates of these gases were 3 sccm, 10 sccm, and 2 sccm, respectively, and the film thickness was 90 mm (0.009 μm).

Subsequently, SiH ₄ and H ₂ gases were used as the source gas for the i-type a-Si: H film, and the flow rates of these gases were 30 sccm and 80 sccm, respectively, and the film thickness was 1700 Å.

Subsequently, SiH ₄ , H ₂ gas, and PH ₃ (those diluted to 1000 ppm with H ₂ ) were used as source gases for the n-type a-Si: H film, and the flow rates of these gases were 3 sccm, 30 sccm, and 6 sccm, respectively. The film was deposited with a thickness of 100 mm. The substrate temperature was 220 ° C. for all pin films.

  Next, an ITO film having a thickness of 0.3 μm was deposited by a sputtering apparatus.

On the other hand, as a conductive sheet, a titanium sheet having a thickness of 0.1 mm (size 1 cm × 2 cm)
Porous titanium dioxide was formed. 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 the surface on which the translucent conductive film was formed by the doctor blade method, and baked at 450 ° C. for 20 minutes in the air.

N719 dye is used as the dye, acetonitrile and t-butanol (1: 1 by volume) are used as the solvent used to dissolve the dye, and the support substrate on which the metal oxide semiconductor layer is formed is dissolved in the dye. The dye was supported on the metal oxide semiconductor by immersion in the solution.

  The following electrolytic solution is added to a titanium sheet of a porous titanium dioxide film carrying a dye on a substrate obtained by laminating a first transparent conductive layer, a pin-type amorphous silicon layer, and a second transparent conductive layer on the glass substrate with FTO. And lightly bonded together to evaluate the characteristics.

Here, a gel electrolyte or a solid electrolyte is preferable as the hole transporter, but in this example, iodine (I ₂ ), lithium iodide (LiI) and acetonitrile solutions as liquid electrolytes were prepared and used.

The stacked photoelectric conversion device thus obtained showed high conversion efficiency (10.1%) at 100 mW / cm ² under AM 1.5.

  As described above, in this example, the stacked 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 an example of embodiment of the laminated photoelectric conversion apparatus of this invention. It is sectional drawing which shows the other example of embodiment of the laminated photoelectric conversion apparatus as a reference . It is sectional drawing which shows the further another example of embodiment of the laminated photoelectric conversion apparatus as reference .

1: Stacked photoelectric conversion device 2: Non-single crystal photoelectric conversion device (thin film photoelectric conversion body)
3: Dye-sensitized photoelectric conversion device (dye-sensitized photoelectric converter)
11: Translucent substrate
12: First transparent conductive layer
13: Non-single-crystal photoelectric conversion layer
14: Transparent conductive layer
15: Metal oxide semiconductor
16: Dye
17: Reverse conductivity type transporter
18: Conductive sheet

Claims (3)

The first transparent conductive layer, the non-single-crystal photoelectric conversion layer, and the second transparent conductive layer are formed on the other main surface of the translucent substrate on which light is incident from the one main surface side, from the translucent substrate side. And a catalyst layer, a hole transporter, a dye, and an electron transporter are arranged in this order.   2. The stacked photoelectric conversion device according to claim 1, wherein a peak wavelength of spectral sensitivity of the dye is longer than a spectral sensitivity peak wavelength of the non-single-crystal photoelectric conversion layer.   The stacked photoelectric conversion device according to claim 1, wherein the non-single-crystal photoelectric conversion layer has a pin structure including an i-type amorphous silicon layer.

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