JP2009289571A - Photoelectric conversion module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion module to improve photoelectric conversion efficiency. <P>SOLUTION: The photoelectric conversion module 1 includes first and second photoelectric conversion elements having: a first conductive layer 7 in which a sensitized-dye carrying semiconductor layer 5 is formed; a second conductive layer 3 arranged opposed to the semiconductor layer 5; and a photoelectric converter 6 which contains an electrolyte, and is arranged between the first and second conductive layers. The first conductive layer 7 of the first photoelectric conversion element 1a and the second conductive layer 3 of the second photoelectric conversion element 1b are joined by a plurality of conductors 8; and the plurality of conductors 8 are arranged mutually separated via either photoelectric converter 6 of the first and second photoelectric conversion elements. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion module that contributes to an improvement in photoelectric conversion efficiency.

  In recent years, a dye-sensitized solar cell, which is a type of photoelectric conversion device, does not require a vacuum device for its production, and thus is considered to be a low-cost, low-environmental load-type solar cell. Has been done.

As a conventional dye-sensitized solar cell, for example, the periphery of a first substrate provided with a semiconductor and a second substrate on which a conductive film is formed is sealed with glass frit so that the electrolyte does not leak outside. There is something. A solar cell module using such a dye-sensitized solar cell has a plurality of dye-sensitized solar cells arranged in a plane and disposed between the glass frits of adjacent dye-sensitized solar cells. It is configured to be electrically connected using a metal wire (see, for example, Patent Document 1).
JP 2001-185244 A

  However, in the module structure disclosed in Patent Document 1, since adjacent dye-sensitized solar cells are connected by metal wires arranged between adjacent glass frits, the glass frit and the metal wires are arranged. The area that does not contribute to power generation has increased, and the photoelectric conversion efficiency per unit of the dye-sensitized solar cell has decreased. Therefore, in the photoelectric conversion module formed by connecting such a dye-sensitized solar cell, the photoelectric conversion efficiency is similarly reduced.

  The present invention has been completed in view of the above problems in the prior art, and an object thereof is to provide a dye-sensitized photoelectric conversion module with improved photoelectric conversion efficiency.

  The photoelectric conversion module of the present invention includes a first conductive layer on which a semiconductor layer carrying a sensitizing dye is formed, a second conductive layer disposed so as to face the semiconductor layer, and an electrolyte. A photoelectric conversion module comprising first and second photoelectric conversion elements having a photoelectric conversion body disposed between the first and second conductive layers, wherein the first photoelectric conversion The first conductive layer of the element and the second conductive layer of the second photoelectric conversion element are joined by a plurality of conductors, and the plurality of conductors are the first and second photoelectric conversions. The element is disposed so as to be separated from each other through the photoelectric conversion body of any one of the elements.

  Furthermore, in the present invention, it is preferable that the conductor includes at least one conductive particle of aluminum, chromium, nickel, cobalt, molybdenum, copper, and titanium.

  In the present invention, it is preferable that a protective material is formed on a portion of the conductor excluding a joint portion with the first and second conductive layers.

  Furthermore, in the present invention, it is preferable that the protective material is formed of glass having translucency.

  In the present invention, a sealing member that simultaneously seals the photoelectric conversion body of the first photoelectric conversion element and the photoelectric conversion body of the second photoelectric conversion element, and disposed in the sealing member, It is preferable to further include a wall portion that separates the photoelectric converters.

  According to the photoelectric conversion module of the present invention, the first conductive layer of the first photoelectric conversion element and the second conductive layer of the second photoelectric conversion element are joined by a plurality of conductors, By disposing the conductor so as to be separated from each other via the photoelectric conversion body of the first and second photoelectric conversion elements, the contact area between the conductive layer and the conductor is reduced, The contact area of the photoelectric conversion body in contact with the first and second conductive layers can be increased. As a result, according to the present invention, since the power generation area of each photoelectric conversion element can be increased, the photoelectric conversion efficiency can be improved.

  In the present invention, if the conductor contains at least one kind of conductive particles of aluminum, chromium, nickel, cobalt, molybdenum, copper, and titanium, it is resistant to an electrolyte containing iodine. Since the corrosivity can be increased, the corrosion of the conductor due to the electrolyte can be reduced.

  Moreover, in this invention, if a protective material is formed in the site | part except the junction part with the said 1st and 2nd conductive layer of the said conductor, the corrosion resistance with respect to electrolyte can be improved easily.

  Furthermore, in the present invention, if the protective material is formed of a light-transmitting glass, in addition to the above-described corrosion resistance, light can also be transmitted through the protective material portion. can do.

  In the present invention, a sealing member that simultaneously seals the photoelectric conversion body of the first photoelectric conversion element and the photoelectric conversion body of the second photoelectric conversion element, and disposed in the sealing member, If the configuration further includes a wall portion that separates the photoelectric converters, it is possible to reduce leakage to the outside of the photoelectric converter and to prevent water vapor from entering from the outside. By isolating each other, it is possible to prevent a high potential from being applied.

  Embodiments according to the photoelectric conversion module of the present invention will be described below in detail with reference to FIGS. 1 and 2. In the drawings, the same members are denoted by the same reference numerals and description thereof is omitted. FIG. 2 is drawn with the front substrate side and the porous semiconductor layer omitted so that the inside of the photoelectric conversion module can be easily understood.

  FIG. 1 is a cross-sectional view showing a photoelectric conversion module according to an embodiment of the present invention. FIG. 2 is a plan view showing a photoelectric conversion module according to an embodiment of the present invention. 1 is a cross-sectional view taken along line XX in FIG.

  A photoelectric conversion module 1 according to an embodiment of the present invention includes a translucent substrate 2, a second translucent conductive layer 3 (hereinafter simply referred to as a first translucent conductive layer 3) including a transparent conductive layer provided on the translucent substrate 2. 2), the amorphous silicon layer 12, the intermediate layer 13, the catalyst layer 14, the counter electrode side substrate 9, the second translucent conductive layer 3 and the counter electrode provided on the counter electrode side substrate 9. A first conductive layer 7 to be formed, and a semiconductor layer 5 formed on the first conductive layer 7 and adsorbing (supporting) a sensitizing dye (hereinafter also referred to as a dye) 4. In the photoelectric conversion module, the second light-transmitting conductive layer 3 and the first conductive layer 7 are arranged to face each other, and the second light-transmitting conductive layer 3 and the first conductive layer 7 are disposed. Between the transparent substrate 2 and the counter electrode side substrate 9 so as to seal the photoelectric conversion body 6 and the sealing member 10 so as to seal the photoelectric conversion body 6. Is arranged.

  In FIG. 1, the photoelectric conversion module 1 includes a first conductive layer 7, an amorphous silicon layer 12, an intermediate layer 13, a photoelectric conversion in the plane direction inside the translucent substrate 2 and the counter electrode side substrate 9. Two photoelectric conversion elements each including the body 6, the porous semiconductor layer 5 and the second conductive layer 3 are provided (first optical conversion element 1a and second optical conversion element 1b). FIG. 1 shows a part of the photoelectric conversion module 1, and a structure in which a plurality of paired optical conversion elements are connected is also included in the present invention.

  Further, in the photoelectric conversion module 1, as shown in FIGS. 1 and 2, the second light-transmissive conductive layer 3 of the first photoelectric conversion element 1a and the first conductive layer 7 of the second photoelectric conversion element 1b are used. Are joined by a plurality of conductors 8, and the plurality of conductors 8 are arranged so as to be separated from each other through a part of the photoelectric conversion body 6. Therefore, in the photoelectric conversion module 1, the contact area between the conductive layer and the conductor 8 can be reduced, and the contact area of the photoelectric converter 6 in contact with the first and second conductive layers can be increased. As a result, according to the present invention, the power generation area of each of the photoelectric conversion elements 1a and 1b can be increased, so that the photoelectric conversion efficiency can be improved.

  Moreover, in the photoelectric conversion module 1, the conductor 8 is formed with a protective material 15 at a portion excluding the junction with the first and second conductive layers, and further, the photoelectric conversion element 1a and the photoelectric conversion element 1b Are separated by a wall 16.

  Next, a method for manufacturing the photoelectric conversion module 1 will be described.

  First, a laminated body in which the second translucent conductive layer 3, the amorphous silicon layer 12, and the intermediate layer 13 are integrally laminated in this order on the translucent substrate 2 is formed. The second light-transmissive conductive layer 3, the amorphous silicon layer 12, and the intermediate layer 13 are formed by, for example, a thermal CVD method, a plasma CVD method, a sputtering method, or the like. Next, the first conductive layer 7 is formed on the counter electrode side substrate 9 by sputtering, for example. Next, after the porous semiconductor layer 5 is sintered, the dye 4 is adsorbed on the semiconductor layer 5, and the second light-transmissive conductive layer 3 and the second photoelectric conversion element 1 b of the first photoelectric conversion element 1 a. The first conductive layer 7 is electrically connected through a plurality of conductors 8. Next, the peripheral portions of the translucent substrate 2 and the counter electrode side substrate 9 are joined and sealed with a sealing member 10 made of resin, glass, or the like, and a protective material 15 is formed around the conductor 8. Finally, a photoelectric conversion module is manufactured by injecting an electrolyte solution that becomes a part of the photoelectric conversion body from the through-hole 11 formed in the sealing member 10 and the like and infiltrating the porous semiconductor layer 5. .

  Next, each element which comprises the photoelectric conversion module 1 mentioned above is demonstrated in detail.

<Translucent substrate>
The translucent substrate 2 has a function of supporting the second translucent conductive layer 3. Examples of the material of the translucent substrate 2 include glass such as white plate glass, soda glass, borosilicate glass, inorganic materials such as ceramics, polyethylene terephthalate (PET), polycarbonate (PC), acrylic, polyethylene naphthalate (PEN), A resin material such as polyimide or an organic-inorganic hybrid material is preferable. Specifically, when the translucent substrate 2 is made of white plate glass having a thickness of 0.7 mm, the light transmittance is preferably 92% or more in a wavelength range of 400 to 1100 nm. The translucent substrate 2 made of polyethylene terephthalate (PET) or polycarbonate (PC) has a light transmittance of about 90% for visible light, and a suitable light transmittance is at least the wavelength range of visible light. It is sufficient if it has a light transmittance of 90% or more.

<Second conductive layer>
As the second conductive layer 3, a transparent conductive layer of metal oxide doped with fluorine or metal can be used. Among these, a fluorine-doped tin dioxide film (SnO ₂ : F film) formed by a thermal CVD method is suitable from the viewpoint of heat resistance. In addition, a tin-doped indium oxide film (ITO film) or an impurity-doped indium oxide film (In ₂ O ₃ film) formed by a low-temperature growth sputtering method or a low-temperature spray pyrolysis method can achieve low resistance. Is preferred. Further, an impurity-doped zinc oxide film (ZnO film) formed by a solution growth method is preferable from the viewpoint that it can be formed without using expensive equipment. Note that the first conductive layer 7 may be formed by stacking the above-described materials in various combinations. Further, when the first conductive layer 7 is a transparent conductive layer, a laminated film with improved adhesion and corrosion resistance can be obtained by sequentially laminating a Ti layer, an ITO layer, and a Ti layer. The thickness of such a transparent conductive layer is 0.001 to 10 [mu] m, preferably 0.05 to 2.0 [mu] m from the viewpoint of maintaining high conductivity and high light transmittance.

  Other film forming methods for the transparent conductive layer include a vacuum deposition method, an ion plating method, a dip coating method, and a sol-gel method. By these film growths, it is preferable to form irregularities in the wavelength order of incident light on the surface of the transparent conductive layer, and a light confinement effect can be imparted.

Further, when the second conductive layer 3 is formed of a thin film made of gold, palladium, titanium, aluminum, stainless steel, silver, copper, nickel or the like, it can be formed by, for example, a vacuum evaporation method or a sputtering method. Further, the second conductive layer 7 is a transparent conductive layer (impurity-doped metal oxide layer) such as a SnO ₂ : F layer on the metal layer as described above for preventing corrosion due to the electrolyte of the photoelectric conversion body 6. Or the like may be formed on the translucent substrate 2 made of metal.

<Amorphous silicon layer>
The amorphous silicon layer 12 is preferably formed of a thin film photoelectric conversion layer such as a thin film type amorphous silicon semiconductor layer. More specifically, a first conductive type amorphous silicon semiconductor layer formed on the second conductive layer 3 and an intrinsic type amorphous silicon formed on the first conductive type amorphous silicon semiconductor layer. The semiconductor layer includes a semiconductor layer and a second conductivity type amorphous silicon semiconductor layer formed on the intrinsic type amorphous silicon semiconductor layer. In this case, the band gap of the amorphous silicon layer 12 is 1.8 eV, and since the amorphous silicon layer 30 does not absorb long wavelength light having a wavelength of 650 nm or more, it can transmit long wavelength light, and dye sensitization. It becomes suitable for the laminated structure (tandem structure) with the type photoelectric converter.

  When the intrinsic type amorphous silicon semiconductor layer is amorphous, at least one of the first conductive type amorphous silicon semiconductor layer and the second conductive type amorphous silicon semiconductor layer has microcrystals, or It may be a hydrogenated amorphous silicon alloy-based layer. For example, the first conductivity type amorphous silicon semiconductor layer on the light incident side is more preferably made of hydrogenated amorphous silicon carbide because it can improve the light-transmitting property and reduce the loss of light.

  Further, the first conductive type amorphous silicon semiconductor layer, the intrinsic type amorphous silicon semiconductor layer, and the second conductive type amorphous silicon semiconductor layer are continuously deposited under the respective film forming conditions by chemical vapor deposition. Can do.

For example, the first conductivity type amorphous silicon semiconductor layer is a p-type a-Si: H (H-doped amorphous silicon) layer, and in the case of film formation, SiH ₄ gas, H ₂ gas, B ₂ H _{6 are used} as source gases. Gases (those diluted to 500 ppm with H ₂ ) are used, and the flow rates of these gases are optimized. The thickness of the p-type a-Si: H layer is preferably in the range of 50 to 200 mm, more preferably 80 to 120 mm. If the thickness is less than 50 mm, an internal electric field cannot be formed in the amorphous silicon layer 12, and if the thickness is more than 200 mm, the optical loss increases.

Further, for example, when the intrinsic type amorphous silicon semiconductor layer is formed as an i-type a-Si: H layer, SiH ₄ gas and H ₂ gas are used as source gases, and the flow rates of these gases are optimized. . The thickness of the i-type a-Si: H layer is preferably in the range of 500 to 10000 (0.05 μm to 1 μm), more preferably 2000 to 8000 (0.2 μm to 0.8 μm). If the thickness is less than 2000 mm, sufficient photocurrent cannot be obtained. If the thickness is more than 8000 mm, it is difficult to transmit light to the dye-sensitized photoelectric conversion body 6 on the rear side.

Further, for example, when the second conductive type amorphous silicon semiconductor layer is formed as an n-type a-Si: H layer, SiH ₄ gas, H ₂ gas, PH ₃ gas (H ₂ to 1000 ppm) is used as a source gas. The flow rate of these gases is optimized respectively. The thickness of the n-type a-Si: H layer is preferably in the range of 50 to 200 mm, more preferably 80 to 120 mm. If the thickness is less than 50 mm, an internal electric field cannot be formed in the amorphous silicon layer 12, and if the thickness is more than 200 mm, the optical loss increases.

  The temperature of the translucent substrate 2 when forming the first conductive type amorphous silicon semiconductor layer, the intrinsic type amorphous silicon semiconductor layer, and the second conductive type amorphous silicon semiconductor layer is the temperature of any layer. Is preferably in the range of 150 ° C to 300 ° C, more preferably 180 ° C to 240 ° C.

  On the other hand, not only the tandem of an amorphous silicon solar cell and a dye-sensitized solar cell, but also an amorphous silicon carbide layer and an amorphous silicon nitride layer may be provided. Since the band gap of the amorphous silicon carbide layer and the amorphous silicon nitride layer is 2.2 eV, the ultraviolet light is sufficiently absorbed even in the thin film, and the ultraviolet light is prevented from entering the dye-sensitized photoelectric conversion element. can do.

<Intermediate layer>
The intermediate layer 13 is formed on the amorphous silicon layer 12. The intermediate layer 13 may include at least one of an indium oxide layer, a tin oxide layer, an indium tin oxide (ITO) layer, and an Nb-doped titanium oxide layer, and more specifically, an ITO layer, a tin oxide layer, and the like. And formed by a CVD method, a sputtering method, a spray method or the like. Further, an organic conductive layer or the like may be laminated on an ITO layer, a tin oxide layer, or the like.

  The intermediate layer 13 has a thickness of about 0.05 to 0.15 μm, preferably 0.08 to 0.12 μm. If the thickness is less than 0.05 μm, the peak of light transmittance improvement by the intermediate layer 13 is close to the wavelength of light absorbed by the amorphous silicon layer 12, so that the length of 700 nm or more that transmits to the dye-sensitized photoelectric converter side The effect of increasing the transmittance of wavelength light is reduced. Further, if it exceeds 0.15 μm, the peak of transmittance improvement by the intermediate layer 13 exceeds the wavelength of about 900 nm of the light absorbed by the dye 14, so that the wavelength region effective for power generation of the dye-sensitized photoelectric conversion element is exceeded. The effect of increasing light is reduced. The range of the thickness of the intermediate layer 13 is particularly effective when the refractive index of the amorphous silicon layer 12 is about 3.5 and the refractive index of the intermediate layer 13 made of ITO or the like is about 1.9. is there.

<Catalyst layer>
The catalyst layer 14 is formed in a plurality of islands on the intermediate layer 13, and the thickness is preferably about 0.5 to 20 nm. If the thickness is less than 0.5 nm, the distance between the island-shaped catalyst layers 14 is too large, and it becomes difficult to obtain a catalytic effect. When the thickness exceeds 20 nm, the amount of transmitted light decreases and the entire surface of the amorphous silicon layer 12 is covered with a catalyst layer (metal layer) 14 made of Pt or the like, so that a short circuit between the electrolyte and the amorphous silicon layer 12 is prevented. The effect to avoid may be reduced. The catalyst layer 14 is formed by a sputtering method or the like. However, in order to form a plurality of islands, it can be realized by performing an operation of forming an extremely thin thickness as described above.

  The catalyst layer 14 is preferably made of platinum, palladium, rhodium, carbon or polythiophene. The catalyst layer 14 made of the above-described material can facilitate the exchange of charges between the electrolyte and the amorphous silicon layer 12, and can further increase the overvoltage (voltage applied at the initial stage of driving the photoelectric conversion device). Can be small. Further, since the intermediate layer 13 has conductivity, even if the amorphous silicon layer 12 is incorporated in the same cell as the dye-sensitized photoelectric conversion element, an extra electric field is generated in the electrolyte, and the catalyst layer 14 is peeled off. Can be suppressed. As a result, according to such an embodiment, the reliability of the catalyst layer 14 can be increased, and the amorphous silicon layer 12 can be incorporated in the same cell as the dye-sensitized photoelectric conversion element.

<Counter electrode substrate>
The counter electrode side substrate 9 functions to support the first conductive layer 7 and the photoelectric conversion body 6 on which the semiconductor layer 5 is formed. The material of the counter electrode side substrate 9 is not particularly limited, but it is preferable to select a material having excellent corrosion resistance to the electrolyte. Examples of the material for the counter electrode side substrate 9 include glass such as white plate glass, soda glass, borosilicate glass, inorganic materials such as ceramics, polyethylene terephthalate (PET), polycarbonate (PC), acrylic resin, polyethylene naphthalate ( PEN), a resin material such as polyimide, and an organic-inorganic hybrid material are preferable. In order to secure electrical connection between the front and back surfaces of the counter electrode side substrate 9, a conductive layer made of titanium, stainless steel, aluminum, silver, copper, nickel, or the like may be coated around the counter electrode side substrate 9.

  Further, if the counter electrode side substrate 9 has translucency, light incident from the counter electrode side substrate 9 side can also contribute to photoelectric conversion, which is preferable from the viewpoint of improving photoelectric conversion efficiency. is there. As the counter electrode side substrate 9 having such translucency, those having high light transmissivity at least in the wavelength range of visible light are preferable, and more preferable light transmissivity is at least 90% or more in the wavelength range of visible light. Those having a light transmittance of Specifically, for example, in the case of a white glass substrate having a thickness of 0.7 mm, the light transmittance is 92% or more in the wavelength range of 400 to 1100 nm, and in the case of a substrate of polyethylene terephthalate (PET) or polycarbonate (PC), It is suitable because it has a light transmittance of about 90% in visible light.

  Further, since the counter electrode side substrate 9 also has a function of holding the photoelectric conversion body 6 having a sufficient amount of electrolyte in the photoelectric conversion module 1, the thickness thereof is 0.5 to 0.5 in terms of mechanical strength and cost. The thickness is 50 mm, preferably 1 to 20 mm.

<First conductive layer>
The first conductive layer 7 has a function of extracting a current generated by the semiconductor layer 5 and the photoelectric conversion body 6, and is formed on the counter electrode side substrate 9.

  The first conductive layer 7 is preferably a very thin film such as platinum or carbon having a catalytic function. In addition, an electrodeposited ultrathin film such as gold (Au), palladium (Pd), and aluminum (Al) can be used. In addition, a porous film made of fine particles of these materials, for example, a porous film of carbon fine particles can increase the surface area of the second conductive layer 3 and can contain an electrolyte solution in the pores, thereby converting the conversion efficiency. Can be increased. Since the catalyst layer can be thin, it can also be made translucent.

  Moreover, the 1st conductive layer 7 can utilize various forms according to a use, without being restricted to non-light-transmitting property and translucency. As a material for the non-light-transmitting conductive layer, titanium, stainless steel, aluminum, silver, copper, gold, nickel, molybdenum, or the like is preferable. Further, a resin or conductive resin impregnated with fine particles or fine wires of carbon or metal may be used. Non-translucent conductive layer material with high light reflectivity is made of a single metallic thin film such as aluminum, silver, copper, nickel, titanium, stainless steel, or to prevent corrosion caused by electrolytes. Further, a film made of a metal oxide doped with impurities is preferably coated on a glossy metal thin film. In addition, as another conductive film, a Ti layer, an Al layer, and a Ti layer are sequentially stacked, and it is preferable that the conductive film is formed of a multilayer stacked body that has improved adhesion, corrosion resistance, and light reflectivity. These conductive films can be formed by a vacuum deposition method, an ion plating method, a sputtering method, an electrolytic deposition method, or the like.

As the light-transmitting conductive layer, a tin-doped indium oxide film (ITO film), an impurity-doped indium oxide film (In ₂ O ₃ film), formed by a sputtering method of a low-temperature film growth method or a low-temperature spray pyrolysis method, An impurity-doped tin oxide film (SnO ₂ film), an impurity-doped zinc oxide film (ZnO film), or the like is preferable. Further, a fluorine-doped tin dioxide film (SnO ₂ : F film) or the like formed by a thermal CVD method may be inexpensive. Moreover, the laminated body which improved the adhesiveness which laminated | stacked Ti layer, ITO layer, and Ti layer one by one may be sufficient. In addition, an impurity-doped zinc oxide film (ZnO film) formed by a simple solution growth method may be used.

  As other film forming methods of these films, there are a vacuum deposition method, an ion plating method, a dip coating method, a sol-gel method, and the like. By forming surface irregularities in the wavelength order of incident light on the conductive layer by these film forming methods, a light confinement effect can be imparted. Further, a thin metal film such as Au, Pd, or Al having translucency formed by a vacuum deposition method or a sputtering method may be used. The thickness of the light-transmitting conductive layer is preferably 0.001 to 10 μm from the viewpoint of ensuring high conductivity and high light transmittance.

  Here, when the second conductive layer 3 and the counter electrode side substrate 9 have translucency, light can be incident from either side of the main surface of the photoelectric conversion module 1, so that light can be incident from both main surface sides. Can increase the conversion efficiency.

<Semiconductor layer>
As shown in FIG. 1, the semiconductor layer 5 is formed on the first conductive layer 7 and is porous. As the material and composition of the porous semiconductor layer 5, titanium oxide (TiO ₂ ) is optimal, and as other materials, 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), a metal oxide semiconductor of at least one of metal elements such as tungsten (W), and nitrogen (N), carbon (C), fluorine (F), sulfur (S), chlorine (Cl), One or more kinds of nonmetallic elements such as phosphorus (P) may be contained. Titanium oxide or the like is preferable because it has an electron energy band gap in the range of 2 to 5 eV, which is larger than the energy of visible light. The porous semiconductor layer 5 is preferably an n-type semiconductor whose conduction band is lower than that of the dye 4 in the electron energy level.

Moreover, when forming the semiconductor layer 5 with a titanium oxide, it forms as follows. First, acetylacetone is 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 is applied at a constant speed onto the first conductive layer 7 on the substrate 2 by a doctor blade method, a bar coating method, or the like, and is 300 to 600 ° C., preferably 400 to 500 ° C. in the atmosphere. The porous semiconductor layer 5 is formed by heat treatment for 60 minutes, preferably 20 to 40 minutes. This method is simple and preferable.

As a low-temperature growth method for the porous semiconductor layer 5, an electrodeposition method, an electrophoretic electrodeposition method, a hydrothermal synthesis method, etc. are preferable. A UV treatment such as plasma treatment or thermal catalyst treatment is preferable. The porous semiconductor layer 5 formed by the low temperature growth method is preferably composed of a porous ZnO layer formed by the electrodeposition method, a porous TiO ₂ layer formed by the electrophoretic electrodeposition method, and the like.

Further, the surface of the porous body of the semiconductor layer 5 may be treated with TiCl ₄ , that is, immersed in a TiCl ₄ solution for 10 hours, washed with water, and baked at 450 ° C. for 30 minutes to improve electronic conductivity. Conversion efficiency increases.

  As the semiconductor layer 5, a porous n-type oxide semiconductor layer having a large number of fine pores (having a pore diameter of preferably about 10 to 40 nm and showing a peak conversion efficiency at 22 nm) inside And so on. The semiconductor layer 5 is a granular body, or a linear body such as a needle-shaped body, a tube-shaped body, a columnar body, or a collection of these various linear bodies, and is a porous body. The surface area for adsorbing the dye 4 is increased, and the conversion efficiency can be increased. The semiconductor layer 5 may be a porous body having a porosity of 20 to 80%, more preferably 40 to 60%. The surface area as the light working electrode layer can be increased 1000 times or more by making it porous, and light absorption, photoelectric conversion, and electronic conduction can be performed efficiently.

  The porosity of the semiconductor layer 5 is determined by obtaining an isothermal adsorption curve of a sample by a nitrogen gas adsorption method using a gas adsorption measuring device, and using a BJH (Barrett-Joyner-Halenda) method, a CI (Chemical Ionization) method, a DH ( The pore volume can be obtained by the Dollimore-Heal) method and the like and obtained from the particle density of the sample.

  The shape of the semiconductor layer 5 is preferably a shape having a large surface area and a small electric resistance, and is preferably composed of fine particles or fine linear bodies, for example. The average particle diameter or average wire diameter is preferably 5 to 500 nm, and more preferably 10 to 200 nm. Here, if the lower limit of the average particle diameter or the average wire diameter of 5 to 500 nm is less than this, the material cannot be miniaturized, and if the upper limit exceeds this, the junction area is reduced and the photocurrent is significantly reduced. It depends.

  As described above, if the semiconductor layer 5 is a porous body, the surface of the dye-sensitized photoelectric conversion body formed by adsorbing the dye 4 on the semiconductor layer 5 becomes uneven, thereby bringing about a light confinement effect and further improving the conversion efficiency. Can be increased.

  The thickness of the semiconductor layer 5 is preferably 0.1 to 50 μm, and more preferably 1 to 20 μm. Here, the lower limit value at 0.1 to 50 μm is not suitable for practical use when the thickness is smaller than this, and the upper limit value is not suitable for practical use. This is because light is not incident.

  In addition, an ultrathin dense layer of an n-type oxide semiconductor may be inserted between the semiconductor layer 5 and the light-transmitting substrate 2, and the reverse current can be suppressed, so that the conversion efficiency is increased.

  The porous semiconductor layer 5 is preferably composed of a sintered body of oxide semiconductor fine particles, and the average particle diameter of the oxide semiconductor fine particles is preferably gradually increased in the thickness direction from the substrate 2 side. 5 is preferably composed of a two-layer laminate having different average particle diameters of the oxide semiconductor fine particles. Specifically, the oxide semiconductor fine particles having a small average particle diameter are used on the substrate 2 side, and the oxide semiconductor fine particles (scattering particles) having a large average particle diameter are used on the second conductive layer 3 side. The porous semiconductor layer 5 on the side of the second conductive layer 3 having a large thickness produces a light confinement effect due to light scattering and light reflection, and the conversion efficiency can be increased.

  More specifically, as oxide semiconductor fine particles having a small average particle diameter, 100 wt% (wt%) having an average particle diameter of about 20 nm is used, and as the oxide semiconductor fine particles having a large average particle diameter, the average particle diameter is What is necessary is just to use 70 wt% of about 20 nm and 30 wt% of those having an average particle diameter of about 180 nm. By changing these weight ratios, average particle diameters, and respective film thicknesses, an optimum light confinement effect can be obtained. In addition, by increasing the number of layers from two layers to a plurality of layers, or by coating and forming such that these boundaries do not occur, the average particle size gradually increases in the thickness direction from the first conductive layer 7 side. Can be formed.

<Sealing member>
The sealing member 10 has functions such as preventing the electrolyte solution constituting a part of the photoelectric conversion body 6 from leaking to the outside and reinforcing the mechanical strength.

As a material of the sealing member 10, glass, glass frit mainly composed of carbon, etc. are excellent in sealing performance and weather resistance. Specifically, as the material of the sealing member 10, for example, glass (including Bi ₂ O ₃ , ZnO, B ₂ O ₃ , SiO ₂ , MgO, etc.) or glass frit mixed with carbon (Bi ₂ O ₃ , ZnO, B ₂ O ₃ , SiO ₂ , PbO, ZnO, Al ₂ O ₃ , MgO, etc.). The glass frit containing carbon described above may be mixed into the glass material as carbon particles, and the content thereof is preferably 0.1 to 20% by weight.

  The thickness of the sealing member 10 is 10 μm to 100 μm, preferably 30 μm to 60 μm. It also seals heat shield, heat resistance, low contamination, antibacterial, antifungal, design, brazing and abrasion resistance, antistatic, far infrared radiation, acid resistance, corrosion resistance, environmental compatibility, etc. By giving to the stop member 10, reliability and commercial property can be improved more.

<Wall>
The wall portion 16 has a function of separating the photoelectric conversion bodies 6 of the adjacent photoelectric conversion elements 1 a and 1 b in the photoelectric conversion module 1. As the material of the wall portion 16, for example, a resin material such as an epoxy resin, a vinyl acetate resin, an olefin resin, or a glass material can be used. Moreover, since there is only one wall portion 16 between the adjacent photoelectric conversion element 1a and the photoelectric conversion element 1b, the photoelectric conversion element of the photoelectric conversion element can be obtained without excessively narrowing the power generation region of the photoelectric conversion element. The converters can be separated from each other.

<Conductor>
The conductor 8 has a function of electrically connecting the first conductive layer 7 of the first photoelectric conversion element 1a and the second conductive layer 3 of the second photoelectric conversion element 1b.

  The shape of the conductor 8 is, for example, a columnar shape, and may be a columnar shape, a prismatic shape, or the like. Such a conductor 8 is formed by, for example, a screen printing method or a dispenser method.

  As a material of the conductor 8, for example, an organic conductor such as titanium, stainless steel, aluminum, silver, copper, gold, nickel, cobalt, metal having corrosion resistance to an electrolyte containing iodine, molybdenum, or the like, or carbon is preferable. It is. Further, the conductor 8 has corrosion resistance against an electrolyte containing iodine on the surface of an insulator such as a resin material or silicon dioxide, and has conductivity, such as a titanium layer, a stainless steel layer, and a metal oxide layer. You may form with what coat | covered. Moreover, the average particle diameter of the metal particle used as the metal material described above is preferably 0.5 to 15 μm. If the average particle diameter is less than 0.5 μm, the contribution to conductivity is reduced. The desired pattern accuracy of the paste containing conductive particles may be reduced. The width of the conductor 8 (diameter in the case of a cylindrical shape) is preferably 100 μm to 2 mm, and is excellent in the manufacturing process without excessively reducing the power generation region.

  On the other hand, if the conductor 8 contains glass frit (low melting point glass) in the metal material as described above, the sinterability of the conductor 8 can be improved, so that the manufacturing process can be simplified. Is preferred. When the content of the glass frit is 5 to 30% by mass, the conductor 8 containing such a glass frit can easily form a pattern for the printing process of the conductor 8 and improve the sinterability. Can do. As the glass frit as described above, lead borosilicate glass, titanium oxide or the like can be used.

  In the present invention, the first conductive layer 7 of the first photoelectric conversion element 1a and the second conductive layer 3 of the adjacent second photoelectric conversion element 1b are connected by a plurality of conductors 8 spaced apart from each other. Therefore, it is possible to adopt a configuration in which the photoelectric conversion body 6 is spread over almost the whole of the adjacent photoelectric conversion elements through the interval between the plurality of conductors 8. For this reason, the conductor 8 is arranged via the photoelectric converter 6. From such a viewpoint, the gap between the conductors 8 is preferably about 200 μm or more. In addition, the gap between the conductors 8 is preferably about 5 mm or less in terms of reducing resistance loss due to current flowing through the first conductive layer 7 and the second conductive layer 3.

In addition, as shown in FIG. 2, in the photoelectric conversion module 1, the area (occupied area in plan view) of the conductor 8 required for connecting the first and second conductive layers 3 and 7 is reduced. Incident light can be effectively used, and photoelectric conversion characteristics can be improved. From such a viewpoint, the cross-sectional area (corresponding to the occupied area in a plan view) in the cross section of the conductor 8 is preferably about 1 mm ² (upper limit) or less per piece. Moreover, the cross-sectional area in the cross section of the conductor 8 is good about 0.01 mm < ² > (lower limit) or more per piece at the point which forms the column shape stable in strength.

  In the photoelectric conversion module 1, the first and second conductive layers 3 and 7 can be stably connected by providing a plurality of conductors 8, and a plurality of connection points can be provided. Even if the conductor 8 is deteriorated, a significant decrease in conduction characteristics can be suppressed, so that the reliability of the photoelectric conversion module can be improved.

<Protective material>
The protective material 15 has a function of protecting the conductor 8 from the electrolyte of the photoelectric converter 6. Since this protective material 15 should just be coat | covered around the conductor 8 which contacts the photoelectric conversion body 9, narrowing of an electric power generation area | region can be reduced. The protective material 15 should just have the corrosion resistance with respect to electrolyte, for example, can use glass suitably. Such glasses, for example, _{Bi 2 O 3, ZnO, B} 2 O 3, good those containing SiO 2, MgO and the like. Moreover, since the protective material 15 can be baked by laser beam irradiation simultaneously with the sealing member 10 if the sealing member 10 is made of glass, if the sealing member 10 is made of glass, the manufacturing process can be simplified. To preferred. Further, the thickness of the protective material 15 is preferably 100 to 300 μm. If the thickness is less than 100 μm, the conductor 8 may be exposed to the electrolyte in terms of the accuracy of the formation pattern, and if it exceeds 300 μm, the light receiving area is easily reduced. Become.

  Furthermore, if the protective material 15 is made of a light-transmitting material (glass), light can be transmitted through the protective material 15, which is preferable from the viewpoint of increasing the photoelectric conversion efficiency.

<Dye>
Examples of the dye 4 include ruthenium-tris, ruthenium-bis, osmium-tris, osmium-bis type transition metal complexes, polynuclear complexes, or ruthenium-cis-diaqua-bipyridyl complexes, or phthalocyanines, porphyrins, and polycyclic aromatics. A xanthene dye such as a compound or rhodamine B is preferable.

  In order to adsorb the dye 4 to the porous semiconductor layer 5, it is effective that the dye 4 has at least one carboxyl group, sulfonyl group, hydroxamic acid group, alkoxy group, aryl group, phosphoryl group as a substituent. It is. Here, the substituent may be any as long as it can strongly chemisorb the dye 4 itself to the porous semiconductor layer 5 and can easily transfer charges from the excited dye 4 to the porous semiconductor layer 5.

  Examples of the method for adsorbing the dye 4 to the porous semiconductor layer 5 include a method of immersing the porous semiconductor layer 5 formed on the substrate 2 in a solution in which the dye 4 is dissolved.

In the process of manufacturing the photoelectric conversion module 1 of the present invention, the dye 4 is adsorbed to the porous semiconductor layer 5. Examples of the solvent of the solution for dissolving the dye 4 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. The concentration of the dye 4 in the solution is preferably about 5 × 10 ⁻⁵ to 2 × 10 ⁻³ mol / l (l (liter): 1000 cm ³ ).

  When adsorbing the dye 4 to the porous semiconductor layer 5, the conditions of the temperature of the solution and the atmosphere are not particularly limited, and examples thereof include conditions of atmospheric pressure or in vacuum, room temperature, or heating of the substrate 2. The time required for adsorption of the dye 4 can be appropriately adjusted depending on the kind of the dye 4 and the solution, the concentration of the solution, the circulation amount of the dye solution, and the like. Thereby, the dye 4 can be adsorbed to the porous semiconductor layer 5.

<Photoelectric converter>
The photoelectric conversion body 6 has a function of converting light incident from the outside into electricity, and includes an electrolyte. As the electrolyte, a fixed electrolyte, a liquid electrolyte, and a gel electrolyte can be used. As the fixed electrolyte, a polymer electrolyte, a conductive polymer such as polythiophene / polypyrrole or polyphenylene vinylene, or an organic fixed electrolyte such as a fullerene derivative, a pentacene derivative, a perylene derivative, or a triphenyldiamine derivative can be used.

  Further, as the liquid electrolyte and the gel electrolyte, those in which a quaternary ammonium salt, a Li salt, or the like is dissolved in a solvent are used. Specifically, as the composition of the electrolyte solution, for example, a solution prepared by mixing tetrapropylammonium iodide, lithium iodide, iodine or the like with ethylene carbonate, acetonitrile, methoxypropionitrile, or the like can be used.

  The thickness of the electrolyte is preferably about 0.01 to 500 μm. If the thickness is less than 0.1 μm, the positive electrode side (amorphous silicon layer 12 side) and the counter electrode side (dye-sensitized photoelectric conversion element side) may come into contact with each other to cause a short circuit. When the thickness exceeds 500 μm, the photoelectric conversion efficiency is likely to decrease due to an increase in the electrolyte as a resistance component, and when the electrolyte is a liquid electrolyte, a sealing failure due to an increase in the liquid portion is likely to occur.

  In the present invention, the photoelectric conversion element composed of the first conductive layer 7, the porous semiconductor layer 5 adsorbing the dye 4, the photoelectric conversion body 6, and the second conductive layer 3 is divided into one element in the thickness direction. It is good also as a structure which laminated | stacked not only what was provided but multiple elements in the thickness direction. Furthermore, the use of the photoelectric conversion module 1 of the present invention is not limited to a solar cell, but can be applied as long as it has a photoelectric conversion function, and can be applied to various light receiving elements, optical sensors, and the like. In this embodiment, the tandem type including an amorphous silicon solar cell and a dye-sensitized solar cell is described in detail, but the present invention is not limited to this example.

  Examples of the photoelectric conversion module of the present invention will be described below.

  First, as a translucent substrate 2, a second conductive layer having a thickness of 0.2 μm made of tin-doped indium oxide (ITO) having a sheet resistance of 5Ω / □ (square) as a second conductive layer 3 on one main surface thereof. 3 was used (length 5 cm × width 5 cm × thickness 2 mm). A 0.05 μm thick Nb-doped titanium oxide film was formed on the ITO.

  Next, by applying a resist on the second conductive layer 3 and etching, patterning was performed so that four regions of the strip-shaped second conductive layer 3 were arranged. Of the four strip-shaped regions, one end also serving as an external electrode has a size of 4 cm in length × 1.5 cm in width, and the other three have a size of 4 cm in length × 1 cm in width. The interval between the regions was 3 mm. Thereby, four photoelectric conversion elements connected in series were arranged in a plane.

  Using a plasma CVD apparatus, a p-type a-Si: H layer as the first conductive type amorphous silicon semiconductor layer, an intrinsic type amorphous silicon semiconductor on the second conductive layer 3 of the translucent substrate 2. An i-type a-Si: H layer as a layer and an n-type a-Si: H layer as a second conductivity type amorphous silicon semiconductor layer were successively deposited in a vacuum.

SiH ₄ gas and B ₂ H ₆ gas (diluted with H ₂ ) are used as source gases for forming the p-type a-Si: H layer, and the flow rates of these gases are set to 2.7 sccm and 9 sccm, respectively. , And a thickness of 100 mm (0.01 μm).

Next, SiH ₄ gas and H ₂ gas are used as source gases for forming the i-type a-Si: H layer, and the flow rates of these gases are 5 sccm and 20 sccm, respectively, and the thickness is 6000 mm (0.6 μm). It was deposited with.

Next, SiH ₄ gas, H ₂ gas, and PH ₃ gas (diluted with H ₂ ) are used as source gases for forming the n-type a-Si: H layer, and the flow rates of these gases are 2 respectively. It was deposited at a thickness of 200 cm (0.02 μm) as 0.7 sccm, 37 sccm, and 2.8 sccm.

  Note that the temperature of the glass substrate was 200 ° C. in any of the formation of the p-type a-Si: H layer, the i-type a-Si: H layer, and the n-type a-Si: H layer.

  As described above, the amorphous silicon layer 12 composed of a p-type a-Si: H layer, an i-type a-Si: H layer, and an n-type a-Si: H layer having a thickness of 0.63 μm and a refractive index of 3.5. Formed.

  Next, an ITO layer having a refractive index of 1.9 was formed as the intermediate layer 13 with a thickness of 100 nm. On this, the platinum layer as the catalyst layer 14 was formed with thickness 5nm using the sputtering device and the Pt target. At this time, since the Pt layer was thin, the resistance was high, and the sheet resistance of the Pt layer separately formed on the glass substrate in the same manner could not be measured.

  Next, a glass substrate (length 5 cm × width 5 cm × thickness 2 mm) in which a fluorine-doped tin oxide film of 1 μm was formed as the first conductive layer 3 on the counter electrode side substrate 9 was used. The first conductive layer 3 was patterned so as to be configured in series in combination with the strip-shaped pattern formed on the second conductive layer 7.

Next, a porous semiconductor layer 5 made of titanium dioxide was formed on each region of the first conductive layer 7. This porous semiconductor layer 5 was formed as follows. First, acetylacetone was added to a TiO ₂ anatase powder (average particle size 20 nm), and then kneaded with deionized water to prepare a titanium oxide paste stabilized with a surfactant. The prepared paste was applied onto each region of the first conductive layer 7 at a constant speed by a doctor blade method, and baked at 450 ° C. for 30 minutes in the atmosphere.

  Next, as a paste for forming the conductor body 8, the conductive material is mainly composed of molybdenum particles, mixed with glass frit (glass components: lead borosilicate glass, titanium oxide, etc.), epoxy resin binder and butyl acetate solvent. In order to connect the first conductive layer 7 and the second conductive layer 3 by using a paste, the end portion of the first conductive layer 3 on one main surface of the counter electrode side substrate 9, A plurality of conductive pastes were formed side by side in a circular shape in plan view in a region where the layer 7 and the second conductive layer 3 overlap in plan view.

  In the conductive paste, the molybdenum particle content was 90% by weight, the glass frit content was 3% by weight, the epoxy resin binder content was 3% by weight, and the butyl acetate solvent content was 4% by weight. It was. The average particle diameter of the molybdenum particles was 2 μm.

Next, a glass paste which contains Bi ₂ O ₃ , ZnO, B ₂ O ₃ , SiO ₂ and MgO as glass components, and further becomes a sealing member 10 made of carbon particles, an epoxy resin binder, and a butyl acetate solvent is dispensed by a dispenser. It apply | coated to the peripheral part of the counter electrode side board | substrate 9, and it applied so that the conductor 8 might be covered. In the glass paste, the glass component content was 86% by weight, the carbon particle content was 7% by weight, the epoxy resin binder content was 3% by weight, and the butyl acetate solvent content was 4% by weight. The average particle size of the carbon particles was 4 μm.

  At this time, in order to form the through-hole 11 in a part of the sealing member 10, a through-hole having a square opening size of about 50 × 500 μm is applied to two places of the applied glass paste layer by a dispenser method. Formed.

  The wall 16 was made of DuPont's admissible resin and cured at 200 ° C. to form a separation wall.

  The translucent substrate 2 and the counter electrode side substrate 9 are arranged facing each other so that the first conductive layer 7 and the second conductive layer 3 face each other, and the conductive paste layer and the glass paste layer are irradiated with carbon dioxide laser light. Then, the conductor 8 was fired and sealed with the sealing member 10.

  Next, the dye 4 solution is injected into the photoelectric conversion module 1 through the through-hole 11 using a tubing pump, and the dye 4 solution is circulated in the photoelectric conversion module 1 for 5 hours at a flow rate of 5 ml per minute at room temperature. The dye 4 was adsorbed on the semiconductor layer 5. Dye 4 solution (Dye 4 content is 0.3 mmol / l) is prepared by dissolving Dye 4 (Solaronics SA “N719”) in solvent acetonitrile and t-butanol (1: 1 by volume). Was used.

Next, the electrolyte solution was infiltrated into the porous semiconductor layer 5 through the through hole 11. In this example, iodine (I ₂ ), lithium iodide (LiI), and an acetonitrile solution, which are liquid electrolytes, were prepared and used as the electrolyte.

  Next, the sheet | seat which consists of olefin resin was covered so that the through-hole 11 might be plugged from the outside, and it heated and formed the through-hole sealing part.

When the photoelectric conversion characteristics of the photoelectric conversion module 1 obtained in this way were evaluated, the conversion efficiency was 7.0% at AM 1.5 and 100 mW / cm ² . When this photoelectric conversion module 1 was subjected to a high temperature standing test in the dark at 85 ° C., the photoelectric conversion efficiency exceeding 75% before the test was maintained even after 100 hours.

  As described above, it was confirmed that the photoelectric conversion module 1 of the present example has high conversion efficiency and exhibits higher durability.

It is sectional drawing which shows an example of embodiment about the photoelectric conversion module of this invention. It is a top view which shows an example of embodiment about the photoelectric conversion module of this invention.

Explanation of symbols

1: Photoelectric conversion module 1a, 1b: Photoelectric conversion element 2: Translucent substrate 3: Second conductive layer 4: Sensitizing dye 5: Semiconductor layer
6: photoelectric conversion body 7: first conductive layer 8: conductor 9: counter electrode side substrate 10: sealing member 11: through hole 12: amorphous silicon layer 13: intermediate layer 14: catalyst layer 15: protective material 16 : Wall

Claims (5)

A first conductive layer on which a semiconductor layer carrying a sensitizing dye is formed; a second conductive layer disposed so as to face the semiconductor layer; and an electrolyte. A photoelectric conversion module comprising a first and a second photoelectric conversion element having a photoelectric conversion body disposed between the conductive layers,
The first conductive layer of the first photoelectric conversion element and the second conductive layer of the second photoelectric conversion element are joined by a plurality of conductors,
The photoelectric conversion module, wherein the plurality of conductors are arranged so as to be separated from each other via the photoelectric conversion body of any of the first and second photoelectric conversion elements.   2. The photoelectric conversion module according to claim 1, wherein the conductor includes at least one kind of conductive particles of aluminum, chromium, nickel, cobalt, molybdenum, copper, and titanium.   2. The photoelectric conversion module according to claim 1, wherein a protective material is formed on a portion of the conductor excluding a joint portion with the first and second conductive layers.   The said protective material is formed with the glass which has translucency, The photoelectric conversion module in any one of Claims 1-3 characterized by the above-mentioned.   A sealing member that simultaneously seals the photoelectric conversion body of the first photoelectric conversion element and the photoelectric conversion body of the second photoelectric conversion element; and disposed within the sealing member; The photoelectric conversion module according to claim 1, further comprising a wall portion to be separated.