JP2008204881A - Photoelectric conversion module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion module enhancing conversion efficiency and securing reliability. <P>SOLUTION: A photoelectric conversion element is equipped with a first conductive layer 3 which is a porous semiconductor layer 5 carried with sensitized-dye 4 and working as one electrode, a second conductive layer 7 countered to the porous semiconductor layer 5 as a counter electrode, and an electrolyte 6 arranged between the first and second conductors 3, 7. The photoelectric conversion module 1 is formed by arranging a plurality of photoelectric conversion elements, and the electrolyte 6 is continuously arranged over the whole of the plurality of photoelectric conversion elements. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion module in which a plurality of photoelectric conversion elements such as solar cells and light receiving elements excellent in photoelectric conversion efficiency and reliability are formed.

  Conventionally, a dye-sensitized solar cell, which is a type of photoelectric conversion device, does not require a vacuum device for its production, so it is considered to be a low-cost, low-environmental load-type solar cell, and is actively researched and developed. Has been done.

  In Patent Document 1, a photoactive electrode substrate in which a photosensitizer complex in which a ruthenium complex dye or the like is attached as a photosensitizer to titanium dioxide coated on a conductive glass substrate, and conductive glass A counter electrode side substrate in which a counter electrode layer of platinum or carbon is formed on a substrate, a porous titanium oxide layer and a counter electrode layer are opposed to each other, both substrates are bonded together, and an iodine / iodide redox pair is included between these substrates There is described a dye-sensitized solar cell having a structure in which an electrolyte solution is filled and filled from a through-hole formed in a counter electrode side substrate, and the through hole of the counter electrode side substrate is closed.

  Patent Document 2 describes a dye-sensitized solar cell in which the periphery of a first substrate provided with a semiconductor and a second substrate provided with a conductive film are sealed with glass frit. As a result, the leakage of the electrolytic solution or volatilization is reduced by improving the sealing performance, the electrolytic solution can be sufficiently retained, and the photoelectric conversion efficiency (hereinafter also referred to as conversion efficiency) stable for a long period of time. ) Can be obtained.

The large-area dye-sensitized solar cell described in Patent Document 3 is made of titanium, platinum, gold, etc., and uses a metal grid in which an infinite number of openings are formed. The metal grid is made of titanium oxide or the like. This is a structure in which an oxide semiconductor sintered product is integrally bonded to form a photoelectrode. With this configuration, the specific resistance of the metal grid is significantly lower than that of a conductive thin film such as ITO or FTO having a large specific resistance, and a low resistance can be realized.
JP 2002-512729 A JP 2001-185244 A JP 2003-123855 A

  However, as in the configurations of Patent Documents 1 and 2, in the cell structure in which two substrates of the photoactive electrode substrate and the counter electrode side substrate are bonded, the surface of the porous titanium oxide layer adsorbing the sensitizing dye and the surface of the counter electrode It was difficult to manufacture the gap filled with the electrolyte with a narrow and constant gap, and it was difficult to manufacture a product having high conversion efficiency and stability and high reliability.

  Further, when the substrate size is increased as in the large-area dye-sensitized solar cell of Patent Document 3, it is in series even if a low-resistance metal grid is introduced as compared with a conductive thin film such as ITO or FTO having a large specific resistance. Resistance becomes a problem.

  Furthermore, when used outdoors, it is necessary to have a module configuration in which the voltage is increased by connecting them in series, and the conventional technology cannot achieve both improvement in conversion efficiency and ensuring reliability.

  Therefore, the present invention has been completed in view of the above problems in the prior art, and its purpose is to achieve dye-sensitized photoelectric conversion capable of achieving both improvement in conversion efficiency and ensuring high reliability. Is to provide modules.

  The photoelectric conversion module of the present invention includes a first conductive layer as one electrode on which a porous semiconductor layer carrying a sensitizing dye is formed, and a counter electrode disposed to face the porous semiconductor layer. A photoelectric conversion module in which a plurality of photoelectric conversion elements each including a second conductive layer and an electrolyte disposed between the first and second conductive layers are arranged, the plurality of photoelectric conversions The electrolyte is arranged to be continuous over the entire element.

  In the photoelectric conversion module of the present invention, preferably, the first conductive layer of the photoelectric conversion element and the second conductive layer of the adjacent photoelectric conversion element are connected by a plurality of conductors separated from each other. It is characterized by being.

  The photoelectric conversion module of the present invention is preferably characterized in that the conductor is covered with a glass layer.

  In the photoelectric conversion module of the present invention, it is preferable that the conductor includes at least one kind of conductive particles of aluminum, chromium, nickel, cobalt, and titanium.

  In the photoelectric conversion module of the present invention, preferably, the entire periphery of the plurality of photoelectric conversion elements is sealed with a sealing member, and the first conductive layer and the second conductive layer are sealed. It is in contact with the stop member through a metal thin film.

  According to the photoelectric conversion module of the present invention, the first conductive layer as one electrode on which the porous semiconductor layer carrying the sensitizing dye is formed, and the counter electrode disposed so as to face the porous semiconductor layer A photoelectric conversion module in which a plurality of photoelectric conversion elements each including a second conductive layer and an electrolyte disposed between the first and second conductive layers are arranged, the plurality of photoelectric conversion elements By arranging the electrolyte so as to be continuous over the entire surface, it becomes unnecessary to provide a through hole for injecting the electrolyte for each photoelectric conversion element, and the injection of the electrolyte becomes easy. It is possible to easily move to the inside of the chamber and achieve high conversion efficiency stably.

  In addition, since a plurality of photoelectric conversion elements are formed side by side on a single conductive substrate or the like, series connection or parallel connection can be freely selected, and a desired voltage and current can be output. Is easy.

  In the photoelectric conversion module of the present invention, preferably, the first conductive layer of the photoelectric conversion element and the second conductive layer of the adjacent photoelectric conversion element are connected by a plurality of conductors separated from each other. Therefore, the electrolyte can be easily spread so that the electrolyte continues throughout the plurality of photoelectric conversion elements through the interval between the plurality of conductors. Further, the first and second conductive layers can be stably connected by the plurality of conductors, and the reliability of the photoelectric conversion module is increased. In addition, since the area of the conductor required for connecting the first and second conductive layers (occupied area in plan view) is reduced, incident light to the photoelectric conversion module can be used effectively, and photoelectric conversion characteristics are improved. Can be made.

  In the photoelectric conversion module of the present invention, preferably, since the conductor is covered with the glass layer, the conductor does not come into contact with the corrosive electrolyte, so that the reliability can be improved. Moreover, when the sealing member that seals the plurality of photoelectric conversion elements is made of a resin, it is possible to suppress deterioration of the conductor due to oxygen or moisture that has passed through the sealing member contacting the conductor, Reliability can be increased.

  In the photoelectric conversion module of the present invention, preferably, the conductor includes at least one kind of conductive particles of aluminum, chromium, nickel, cobalt, and titanium. Therefore, these conductive particles are used for an electrolyte containing iodine. Therefore, the corrosion of the conductor due to the electrolyte can be suppressed.

  In the photoelectric conversion module of the present invention, preferably, the entire periphery of the plurality of photoelectric conversion elements is sealed with a sealing member, and the first conductive layer and the second conductive layer are formed of a sealing member and a metal. Since they are in contact with each other through the thin film, it is possible to prevent the first and second conductive layers from being deteriorated by heating when the sealing member is formed by welding by irradiation with laser light.

  Embodiments of the photoelectric conversion module and the manufacturing method thereof according to the present invention will be described below in detail with reference to FIGS. In addition, in each figure, the same code | symbol is attached | subjected to the same member. Further, the first conductive layer 3 in FIG. 2 is drawn with a half length so that the inside of the photoelectric conversion module can be easily understood.

  A cross-sectional view of the photoelectric conversion module of the present invention is shown in FIG. The photoelectric conversion module 1 of FIG. 1 includes a first conductive layer 3 made of a transparent conductive layer or the like on a substrate 2 and a porous semiconductor layer 5 that adsorbs (supports) a sensitizing dye (hereinafter also referred to as a dye) 4. A second conductive layer 7 as a counter electrode layer is formed on the counter electrode side substrate 9, and the substrate 2 and the counter electrode side substrate 9 are disposed so that the porous semiconductor layer 5 and the second conductive layer 7 face each other. The electrolyte 6 is disposed between them, and the outer peripheral portions of the substrate 2 and the counter electrode side substrate 9 are sealed with a glass sealing layer 10.

  Further, inside the substrate 2 and the counter electrode side substrate 9, a set (photoelectric conversion element unit) of the first conductive layer 3, the porous semiconductor layer 5, the electrolyte 6, and the second conductive layer 7 is provided in the plane direction. A plurality of sets are formed, and the electrolyte 6 is disposed so as to be continuous over the whole of the plurality of photoelectric conversion elements.

  The photoelectric conversion module 1 of FIG. 1 forms a laminate in which a first conductive layer 3 and a porous semiconductor layer 5 are integrally laminated in this order on a substrate 2, and then immersed in a dye 4 solution. In addition, the dye 4 is adsorbed on the porous semiconductor layer 5 and the first conductive layer 3 and the second conductive layer 7 are electrically connected to the counter electrode side substrate 9 via the conductor 8. The counter electrode side substrate 9 is arranged on the upper side of the electrolyte 6 region, and the peripheral portions of the substrate 2 and the counter electrode side substrate 9 are then sealed by bonding with a sealing member 10 made of resin, glass or the like, and simultaneously conductive. The sealing member 10 is also formed around the body 8, and the solution of the electrolyte 6 is injected from the through hole formed in the sealing member 10 and the like to infiltrate the porous semiconductor layer 5.

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

<First conductive layer>
The substrate 2 and the first conductive layer 3 may be formed by forming a metal layer or a transparent conductive layer on an insulating substrate. When the substrate 2 has translucency, the porous semiconductor layer 5 can be formed on the substrate 2 which is a light working side electrode substrate, and the porous semiconductor layer 5 can be arranged on the light incident side, so that the conversion efficiency is high. It becomes. Moreover, when the board | substrate 2 and the counter electrode side board | substrate 9 have translucency, since light can enter from any surface of the main surface of the photoelectric conversion module 1, it makes light incident from both main surface sides, and converts Efficiency can be increased.

  The material of the substrate 2 is glass such as white plate glass, soda glass, borosilicate glass, inorganic materials such as ceramics, resin such as polyethylene terephthalate (PET), polycarbonate (PC), acrylic, polyethylene naphthalate (PEN), polyimide, etc. Materials, organic-inorganic hybrid materials, etc. are preferable.

  As the translucent substrate 2, at least in the wavelength range of visible light, for example, in the case of a white glass substrate having a thickness of 0.7 mm, it has a light transmittance of 92% or more in the wavelength range of 400 to 1100 nm. In the case of a polyethylene terephthalate (PET) or polycarbonate (PC) substrate, the light transmittance is about 90% for visible light, and the preferred light transmittance is at least 90% light transmission in the visible light wavelength range. Any substrate having a rate can be used. As the material of the light-transmitting substrate 2, glass such as white plate glass, soda glass, borosilicate glass, inorganic materials such as ceramics, polyethylene terephthalate (PET), polycarbonate (PC), acrylic, polyethylene naphthalate (PEN) , Resin materials such as polyimide, and organic-inorganic hybrid materials are preferable.

As the first conductive layer 3, a transparent conductive layer of metal oxide doped with fluorine or metal can be used. Among them, a fluorine-doped tin dioxide film (SnO ₂ : F film) formed by a thermal CVD method has heat resistance and is particularly good. Further, it is sputtering or low tin-doped was formed by a spray pyrolysis method indium oxide film (ITO film) of indium oxide film or impurities doped (In ₂ O ₃ film) or the like of low temperature growth. In addition, an impurity-doped zinc oxide film (ZnO film) formed by a solution growth method is preferable. Further, these transparent conductive layers may be laminated and used in various combinations. In addition, the transparent conductive layer may be a laminated layer of Ti layer, ITO layer and Ti layer in order, and it becomes a laminated film with improved adhesion and corrosion resistance. The thickness of the transparent conductive layer is high in terms of conductivity and high light transmittance. 0.001-10 micrometers, Preferably 0.05-2.0 micrometers is good. When the thickness is less than 0.001 μm, the resistance of the transparent conductive layer increases. When the thickness exceeds 10 μm, the light transmittance of the transparent conductive layer decreases.

  Other film forming methods for the transparent conductive layer include a vacuum deposition method, an ion plating method, a dip coating method, a sol-gel method, and the like. 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, as the first conductive layer 3, a thin film made of gold, palladium, titanium, aluminum, stainless steel, silver, copper, nickel or the like formed by vacuum deposition or sputtering is formed by vacuum deposition or sputtering. What you did is good. Alternatively, a transparent conductive layer (impurity-doped metal oxide layer) such as a SnO ₂ : F layer or the like may be formed on the substrate 2 made of metal to prevent corrosion by the electrolyte 6.

<Porous semiconductor layer>
As shown in FIG. 1, a porous semiconductor layer 5 is formed on the substrate 2 and the first conductive layer 3. The material and composition of the porous semiconductor layer 5 is optimally titanium oxide (TiO ₂ ), and other materials include titanium (Ti), zinc (Zn), tin (Sn), and niobium (Nb). , Indium (In), yttrium (Y), lanthanum (La), zirconium (Zr), tantalum (Ta), hafnium (Hf), strontium (Sr), barium (Ba), calcium (Ca), vanadium (V) Metal oxide semiconductors of at least one metal element such as tungsten (W) are preferable, and nitrogen (N), carbon (C), fluorine (F), sulfur (S), chlorine (Cl), phosphorus ( One or more non-metallic elements such as 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.

  The porous semiconductor layer 5 is made of titanium dioxide or the like, and has a large number of fine pores (having a pore diameter of preferably about 10 to 40 nm, with a peak conversion efficiency at 22 nm). It may be a porous n-type oxide semiconductor layer or the like. When the pore size of the porous semiconductor layer 5 is less than 10 nm, the penetration and adsorption of the dye 4 are hindered, a sufficient amount of the dye 4 is not absorbed, and the diffusion of the electrolyte 6 is hindered. Increases the conversion efficiency. If the thickness exceeds 40 nm, the specific surface area of the porous semiconductor layer 5 decreases, so that it is necessary to increase the thickness in order to secure the amount of adsorption of the dye 4, and if the thickness is excessively large, light is not easily transmitted. Therefore, the dye 4 cannot absorb light, the movement distance of the charge injected into the porous semiconductor layer 5 becomes long, so that the loss due to the recombination of charges becomes large, and the diffusion distance of the electrolyte 6 also increases. Since the diffusion resistance increases due to the increase, the conversion efficiency also decreases.

  The porous semiconductor layer 5 is a porous body that is a granular body, or a linear body such as a needle-like body, a tubular body, or a columnar body, or a collection of these various linear bodies. By this, the surface area which adsorb | sucks the pigment | dye 4 increases and conversion efficiency can be improved. The porous semiconductor layer 5 is preferably 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 porous semiconductor layer 5 is obtained by obtaining an isothermal adsorption curve of the sample by a nitrogen gas adsorption method using a gas adsorption measuring device, and using a BJH (Barrett-Joyner-Halenda) method or a CI (Chemical Ionization) method. , DH (Dollimore-Heal) method or the like can be used to determine the pore volume and obtain it from the particle density of the sample.

  The shape of the porous 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.

  Further, by forming the porous semiconductor layer 5 as a porous body, the surface as a dye-sensitized photoelectric conversion body formed by adsorbing the dye 4 to the porous body becomes uneven, resulting in a light confinement effect, and conversion efficiency. Can be further enhanced.

  The thickness of the porous semiconductor layer 5 is preferably 0.1 to 50 μm, 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.

When the porous semiconductor layer 5 is made of titanium oxide, it is formed 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 3 on the substrate 2 by a doctor blade method, a bar coating method, or the like, and is 300 to 600 ° C. in air, preferably 400 to 500 ° C. 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 of the porous semiconductor layer 5, an electrodeposition method, an electrophoretic electrodeposition method, a hydrothermal synthesis method or the like is preferable. As a post-treatment for improving electron transport properties, a microwave treatment or a CVD method is used. 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 porous semiconductor layer 5 may be treated with TiCl ₄ treatment, that is, immersed in a TiCl ₄ solution for 10 hours, washed with water, and fired at 450 ° C. for 30 minutes. The conversion efficiency is improved.

  In addition, an ultrathin dense layer of an n-type oxide semiconductor may be inserted between the porous semiconductor layer 5 and the 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. The semiconductor layer 5 is preferably composed of a two-layer laminate in which the average particle diameter of the oxide semiconductor fine particles is different. 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 7 side. The porous semiconductor layer 5 on the side of the second conductive layer 7 having a large thickness produces a light confinement effect due to light scattering and light reflection, so that 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. Further, by increasing the number of stacked layers from two layers to a plurality of layers, or by applying and forming so that these boundaries do not occur, the average particle diameter can be gradually increased from the substrate 2 side in the thickness direction. it can.

<Second conductive layer>
A second conductive layer 7 as a counter electrode layer is formed on the counter electrode side substrate 9. The counter electrode side substrate 9 may be non-translucent or translucent. The counter electrode side substrate 9 is preferably an insulator, and in this case, a material excellent in durability against corrosion by the electrolyte 6 and bonding property with the sealing member 10 can be freely selected. Increases nature.

  As a material of the counter electrode side substrate 9, 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), polyimide For example, a resin material such as an organic-inorganic hybrid material is 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, as the translucent counter electrode side substrate 9, at least in the wavelength range of visible light, for example, in the case of a white glass substrate having a thickness of 0.7 mm, light of 92% or more in a wavelength range of 400 to 1100 nm. In the case of a substrate of polyethylene terephthalate (PET) or polycarbonate (PC), the transmittance is about 90% for visible light, and the preferred light transmittance is 90% at least in the wavelength range of visible light. Any substrate having the above light transmittance can be used.

  Since the counter electrode side substrate 9 is installed for the purpose of holding a sufficient amount of the electrolyte 6 in the photoelectric conversion module 1, the thickness thereof is 0.5 to 50 mm, preferably 1 to 20 mm in terms of mechanical strength and cost. . If the thickness of the substrate 9 is less than 0.5 mm, the mechanical strength cannot be secured, and if it exceeds 50 mm, the cost increases. Moreover, when the counter electrode side board | substrate 9 forms the conductive layer around the insulated substrate, the thickness of the conductive layer is 0.001-10 micrometers, Preferably 0.05-2.0 micrometers is good.

  The second 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 7 and can contain the electrolyte 6 solution in the pores. Efficiency can be increased. Since the catalyst layer can be thin, it can also be made translucent.

  The conductive film complements the conductivity of the catalyst layer. As the conductive film, either a non-light-transmitting layer or a light-transmitting layer can be used depending on the application. As a material for the non-light-transmitting conductive film, 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. As a material for the light-reflective and non-light-transmitting conductive film, a thin metallic thin film such as aluminum, silver, copper, nickel, titanium, stainless steel or the like, or for preventing corrosion by the electrolyte 6 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 laminated, and it is preferable that the conductive film is formed of a multilayer laminated body having improved adhesion, corrosion resistance, and light reflectivity. These conductive films can be formed by vacuum deposition, ion plating, sputtering, electrolytic deposition, or the like.

As the translucent conductive film, a tin-doped indium oxide film (ITO film), an impurity-doped indium oxide film (In ₂ O ₃ film), an impurity formed by a sputtering method of a low-temperature film growth method or a low-temperature spray pyrolysis method A 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 film by these film forming methods, a light confinement effect can be imparted. Further, a thin metal film such as light-transmitting Au, Pd, or Al formed by vacuum vapor deposition or sputtering may be used. The thickness of the light-transmitting conductive film is preferably 0.001 to 10 μm, more preferably 0.05 to 2.0 μm in terms of high conductivity and high light transmittance. When the thickness is less than 0.001 μm, the resistance of the conductive film increases. When the thickness exceeds 10 μm, the light transmittance of the conductive film decreases.

  Here, when the second conductive layer 7 and the substrate 9 have translucency, light can be incident from either of the main surfaces of the photoelectric conversion module 1, and therefore light is incident from both main surfaces. Conversion efficiency can be increased.

<Sealing member>
In FIG. 1, the sealing member 10 prevents the electrolyte 6 solution from leaking to the outside, reinforces the mechanical strength, protects the laminate, and prevents the photoelectric conversion function from deteriorating directly in contact with the external environment. It is provided for the purpose of.

  As a material of the sealing member 10, glass, a glass frit containing carbon as a main component, and the like are particularly excellent in sealing properties and weather resistance.

Specifically, as the material of the sealing member 10, glass (including Bi ₂ O ₃ , ZnO, B ₂ O ₃ , SiO ₂ , MgO, etc.), glass frit mixed with carbon, or the like is used for sealing and Excellent weather resistance, especially good. Carbon may be mixed in the sealing member 10 as carbon particles, and the content thereof is preferably 0.1 to 20% by weight. If it is less than 0.1% by weight, the absorption of the laser beam is reduced. When it exceeds 20% by weight, the formed sealing member 10 exhibits conductivity. The average particle size of the carbon particles is preferably 0.01 to 20 μm. If it is less than 0.01 μm, the surface of the carbon particles is easily oxidized at a high temperature. If it exceeds 20 μm, the thixotropy of the paste containing carbon particles to be the sealing member 10 becomes high, and screen printing becomes difficult.

  The thickness of the sealing member 10 is 0.1 μm to 6 mm, preferably 1 μm to 4 mm. Also seals heat shielding, heat resistance, low contamination, antibacterial, antifungal, design, rust and abrasion resistance, antistatic, far infrared radiation, acid resistance, corrosion resistance, environmental compatibility, etc. By imparting to the member 10, reliability and merchantability can be further improved.

<Conductor>
In FIG. 1, the conductor 8 is installed to electrically connect the second conductive layer 7 and the first conductive layer 3.

  The shape of the conductor 8 is a columnar body such as a columnar shape as shown in FIGS. 1 and 2, and is formed by a screen printing method, a dispenser method, or the like.

  Examples of the conductive layer 8 include those made of a metal having corrosion resistance to the electrolyte 6 such as titanium, stainless steel, aluminum, silver, copper, gold, nickel, and molybdenum, those made of an organic conductor such as carbon, plastic, It is preferable that the surface of an insulator such as silicon dioxide is coated with a titanium layer, a stainless steel layer, a metal oxide layer (having conductivity), etc. having corrosion resistance to the electrolyte 6.

  The conductor 8 may include glass frit (low melting point glass) covered with a glass layer, and more preferably, the conductor 8 is made of aluminum, chromium, nickel, cobalt, or titanium. The thing containing at least 1 sort (s) of electroconductive particle is good. These conductive particles have an effect of reducing corrosion of the conductor 8 by the electrolyte 6 containing iodine.

  For example, the conductor 8 is a columnar body made of low-melting glass and containing about 70 to 95% by weight of conductive particles such as aluminum and nickel. In this case, when the content of the conductive particles is less than 70% by weight, an organic residue tends to be generated. When it exceeds 95% by weight, it becomes difficult to form a print pattern of a paste containing conductive particles to be the conductor 8. Moreover, the average particle diameter of the conductive particles is preferably 0.5 to 15 μm, and if it is less than 0.5 μm, the contribution to imparting conductivity is small. If it exceeds 15 μm, the desired pattern accuracy of the paste containing conductive particles to be the conductor 8 is insufficient.

  The width of the conductor 8 (diameter in the case of a columnar shape) is preferably 100 μm to 2 mm. If the width is less than 100 μm, printing accuracy (shape accuracy) is insufficient with general printing means such as screen printing. The effective area for photoelectric conversion is reduced.

  The glass frit contained in the conductor 8 includes lead borosilicate glass, titanium oxide, or the like as a glass component.

The glass layer covering the conductor 8 is made of glass containing Bi ₂ O ₃ , ZnO, B ₂ O ₃ , SiO ₂ , MgO, etc., and when the sealing member 10 is made of glass, it is made of the same glass component. It may be. In that case, the glass layer can be fired by laser beam irradiation simultaneously with the sealing member 10.

  The thickness of the glass layer covering the conductor 8 is preferably 100 to 300 μm. If the thickness is less than 100 μm, the conductor 8 may be exposed to the electrolyte 6 in terms of the accuracy of the formation pattern, and if it exceeds 300 μm, the light receiving area is reduced. It becomes easy to do.

  In the present invention, since the first conductive layer 3 of the photoelectric conversion element and the second conductive layer 7 of the adjacent photoelectric conversion element are connected by a plurality of conductors 8 spaced apart from each other, The electrolyte 6 can be easily distributed so that the electrolyte 6 continues throughout the plurality of photoelectric conversion elements through the interval between the conductors 8. Further, the dye 4 can be easily distributed in the photoelectric conversion module 1. 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 conductive layer 3 and the conductive layer 7.

  Moreover, the 1st and 2nd conductive layers 3 and 7 can be stably connected by the some conductor 8, and the reliability of a photoelectric conversion module increases. By having a plurality of connection points, even if one conductor 8 is deteriorated, it is not affected in terms of characteristics.

Moreover, since 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 to the photoelectric conversion module can be used effectively, and the 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.

<Metal thin film>
The metal thin film 12 may be made of a metal made of platinum or the like that does not corrode by the electrolyte 6 such as iodine. The metal thin film 12 is formed by sputtering, vapor deposition, or CVD. The patterning of the metal thin film 12 may be performed by forming a film using a metal mask, or may be performed by etching after the film formation. Alternatively, a metal paste may be applied and fired.

  The thickness of the metal thin film 12 is preferably about 0.01 to 1 [mu] m. If the thickness is less than 0.01 [mu] m, the metal thin film 12 has an island shape and the sheet resistance increases, and if it exceeds 1 [mu] m, the cost becomes high.

  It is possible to prevent the first and second conductive layers 3 and 7 from being deteriorated by heating when the sealing member 10 is formed by welding by irradiation with laser light. Further, even if the first and second conductive layers 3 and 7 deteriorate and become high resistance, the metal thin film 12 can ensure low resistance connection to the terminal portion for external connection.

<Dye>
Examples of the dye 4 include ruthenium-tris, ruthenium-bis, osmium-tris, osmium-bis transition metal complexes, polynuclear complexes, ruthenium-cis-diaqua-bipyridyl complexes, 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.

<Electrolyte>
As the electrolyte 6, a quaternary ammonium salt, a Li salt, or the like is used. As the composition of the electrolyte 6 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.

  In the present invention, the electrolyte 6 may be in a liquid form, but may be composed of a chemical gel that changes phase to a gel body. The phase change from the liquid phase body of the chemical gel to the gel body can be performed by heating.

  In the photoelectric conversion module 1 of the present invention, the photoelectric conversion element composed of the first conductive layer 3, the porous semiconductor layer 5 that adsorbs the dye 4, the electrolyte 6, and the second conductive layer 7 is arranged in the thickness direction. The configuration is not limited to that provided for one element, and may be configured by stacking a plurality of elements in the thickness direction.

  Moreover, the use of the photoelectric conversion module 1 of the present invention is not limited to the solar battery, 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.

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

  First, as a substrate 2, a glass substrate in which a first conductive layer 3 having a thickness of 1 μm made of fluorine-doped tin oxide having a sheet resistance of 5Ω / □ (square) as a first conductive layer 3 is formed on one main surface. (Length 5 cm × width 5 cm × thickness 2 mm) was used.

  Next, by applying a resist on the first conductive layer 3 and etching, patterning was performed so that four regions of the strip-shaped first 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.

Next, a porous semiconductor layer 5 made of titanium dioxide was formed on each region of the first conductive layer 3. 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 3 at a constant speed by a doctor blade method, and baked at 450 ° C. for 30 minutes in the atmosphere.

  Next, a glass substrate (length 5 cm × width 5 cm × thickness 2 mm) is used as the counter electrode-side substrate 9, and a sputtering apparatus and a Pt target are used on one main surface thereof as the second conductive layer 7 as a counter electrode layer. The platinum layer was formed with a thickness of about 200 nm so that the sheet resistance was 0.6 Ω / □. At this time, by forming the second conductive layer 7 using a metal mask, four strip-shaped regions were formed in the same manner as the first conductive layer 3.

  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 3 and the second conductive layer 7 by using a paste, the end portion of the second conductive layer 7 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 3 and the second conductive layer 7 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 that 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 coat | covered so that the conductor body 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.

  Arrange the substrate 2 and the counter electrode side substrate 9 so that the porous semiconductor layer 5 and the second conductive layer 7 face each other, and irradiate the conductive paste layer and the glass paste layer with a carbon dioxide laser beam, The conductor body 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 solution of the electrolyte 6 was permeated 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 6.

  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 5.6% 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 70% before the test was maintained even after 100 hours had elapsed.

  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 2: Substrate 3: First conductive layer 4: Sensitizing dye 5: Porous semiconductor layer
6: Electrolyte 7: Second conductive layer 8: Conductor 9: Counter electrode substrate 10: Sealing member 11: Through hole 12: Metal thin film

Claims (5)

  A first conductive layer as one electrode on which a porous semiconductor layer carrying a sensitizing dye is formed, and a second conductive layer as a counter electrode arranged to face the porous semiconductor layer; A photoelectric conversion module in which a plurality of photoelectric conversion elements each having an electrolyte disposed between the first and second conductive layers are arranged, wherein the electrolyte is continuous over the plurality of photoelectric conversion elements. The photoelectric conversion module is arranged so as to perform.   2. The first conductive layer of the photoelectric conversion element and the second conductive layer of the photoelectric conversion element adjacent to each other are connected by a plurality of conductors spaced apart from each other. Photoelectric conversion module.   The photoelectric conversion module according to claim 2, wherein the conductor is covered with a glass layer.   4. The photoelectric conversion module according to claim 2, wherein the conductor includes at least one kind of conductive particles of aluminum, chromium, nickel, cobalt, and titanium.   The entire periphery of the plurality of photoelectric conversion elements is sealed with a sealing member, and the first conductive layer and the second conductive layer are in contact with the sealing member through a metal thin film. The photoelectric conversion module according to claim 1, wherein:

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