JP2010020938A - Dye-sensitized solar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar battery that can stably function as a battery, in which a glass electrode substrate and a metal-electrode substrate are disposed so as to face each other and disadvantages such as the cracking of a cell and the peeling of a sealant, caused by a difference between the thermal expansions of the glass electrode substrate and the metal-electrode substrate, are effectively avoided without a larger area for an electrode substrate or reduction in conversion efficiency. <P>SOLUTION: The dye-sensitized solar battery, in which a power generation area X composed of an electrolyte layer 40 and a semiconductor porous layer 25 that is sensitized with a pigment and a sealing area Y composed of the sealant 50 that connects both electrode substrates are formed between the metal-electrode substrate 20 and the glass electrode substrate 30, is characterized in that a spacing between the metal-electrode substrate 20 and the glass electrode substrate 30 in the sealing area Y is set to be greater than a spacing between both electrode substrates in the power generation area X. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention comprises a metal electrode substrate and a glass electrode substrate arranged to face each other, and a power generation region comprising an electrolyte layer and a semiconductor porous layer sensitized with a dye between the electrodes. Relates to a dye-sensitized solar cell in which is formed.

  Currently, there is great expectation for photovoltaic power generation from the viewpoint of global environmental problems and fossil energy resource depletion problems, and single crystal and polycrystalline silicon photoelectric conversion elements are put into practical use as solar cells. However, this type of solar cell is expensive and has a problem of supply of silicon raw materials, and the practical application of solar cells using materials other than silicon is desired.

  From the above viewpoint, recently, dye-sensitized solar cells have attracted attention as solar cells using materials other than silicon. As shown in FIG. 1, a typical dye-sensitized solar cell includes a metal electrode substrate 1 and a transparent electrode substrate 3 sandwiching a dye-sensitized semiconductor porous layer 5 and an electrolyte layer 7 therebetween. The peripheral portions of the metal electrode substrate 1 and the transparent electrode substrate 3 are sealed with a sealing material 9 so that the electrolyte layer 7 does not leak. That is, the region where the metal electrode substrate 1 and the transparent electrode substrate 3 face each other with the dye-sensitized semiconductor porous layer 5 and the electrolyte layer 7 interposed therebetween is the power generation region X. A sealed region is a sealed region Y.

  In such a dye-sensitized solar cell, the dye-sensitized porous layer 5 is obtained by adsorbing and supporting a sensitizing dye (for example, Ru dye) on a porous layer of an oxide semiconductor such as titanium dioxide. It is formed on the metal electrode substrate 1 through a reverse current prevention layer 10 made of a thin oxide layer or the like. A transparent conductive film 11 such as ITO is formed on the surface of the transparent electrode substrate 3, and a vapor deposition film such as platinum or platinum is further formed as an electron reducing conductive layer 13 thereon.

  In the dye-sensitized solar cell having such a structure, when visible light is irradiated from the transparent electrode substrate 3 side, the dye in the dye-sensitized porous layer 5 is excited, transitions from the ground state to the excited state, and is excited. The dye electrons are injected into the conduction band in the porous layer 5 and move to the transparent electrode substrate 3 through an external circuit (not shown). The electrons that have moved to the transparent electrode substrate 3 are carried by the ions in the electrolyte layer 7 and return to the pigment. Electric energy is extracted by repeating such a process. The power generation mechanism of such a dye-sensitized solar cell is different from a pn junction photoelectric conversion element, in which light capture and electronic conduction are performed in different places, and is very similar to a plant photoelectric conversion process. Yes.

  In such a dye-sensitized solar cell, a glass substrate is widely used as the transparent substrate from the viewpoint of high strength.

By the way, as the sealing material 9 which joins the peripheral part (sealing area | region Y) of the above metal electrode substrates 1 and the transparent electrode substrate 3, various synthetic resins, especially the heat-sealable thermoplastic resin and adhesion | attachment An agent resin or the like is used (see Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 01-220380 JP2007-31218A

  By the way, as the transparent electrode substrate, a glass substrate is widely used. However, when the glass substrate is used, there is a problem that the material of the metal electrode substrate, the structure of the battery, and the like are greatly limited. . That is, some metal electrode substrates differ greatly in thermal expansion coefficient from glass substrates, and when such metal electrode substrates are used in combination with glass substrates, this solar cell received a thermal history. At this time, a large shearing stress is generated in the sealing material 9 that joins the two substrates, and as a result, there is a problem that the cell is cracked or the sealing material 9 is peeled off. There is. When such an inconvenience occurs, naturally, the electrolytic solution forming the electrolyte layer leaks, and the function as a battery is impaired. For example, the linear expansion coefficient of an aluminum substrate is about 23 ppm / ° C, Zn is about 33 ppm / ° C, Stainless Steel (SUS304) and copper are about 17 ppm / ° C, Iron is about 12 ppm / ° C, and Nickel is about 11 ppm / ° C. Quartz glass has a linear expansion coefficient of 0.5 ppm / ° C., Pyrex glass has 3.3 ppm / ° C., and blue plate glass with the largest linear expansion coefficient has 9 ppm / ° C., which is particularly lightweight and inexpensive. In view of the above, an aluminum substrate, a stainless steel substrate, and the like that are useful as a metal substrate are greatly different in thermal expansion coefficient from that of a glass substrate, so that the above-described problems are likely to occur.

  In order to solve the problem due to the difference in thermal expansion coefficient, it is conceivable to increase the stress absorbing ability of the sealing material 9. In order to increase the stress absorbing ability of the sealing material 9, the width and thickness (height) of the sealing material 9 may be increased. However, increasing the width of the sealing material 9 may be a transparent electrode substrate or a metal substrate. Therefore, the battery is unnecessarily enlarged, and cannot be employed from the viewpoint of practicality. Further, increasing the thickness (height) of the sealing material 9 can avoid an increase in the area of the battery, but has a problem of reducing the conversion efficiency of the battery.

  The present inventors presume that the problem of a decrease in conversion efficiency caused by increasing the thickness of the sealing material 9 is caused by a change in the thickness of the electrolyte layer 7 formed in the power generation region X. ing. That is, when the thickness of the sealing material 9 is increased, the distance between the metal electrode substrate and the transparent electrode substrate (glass electrode substrate) is increased. As a result, the thickness of the electrolyte layer 7 is increased. However, in the dye-sensitized solar cell having the structure described above, light is irradiated from the transparent electrode substrate side to generate electric power. Therefore, when the thickness of the electrolyte layer 7 increases, the degree of light absorption in the electrolyte layer 7 increases. The light irradiated to the dye in the dye-sensitized semiconductor layer 5 is attenuated, and as a result, the conversion efficiency is lowered.

  Accordingly, an object of the present invention is to provide a dye-sensitized solar cell in which a glass electrode substrate and a metal electrode substrate are arranged to face each other, without increasing the area of the electrode substrate and reducing the conversion efficiency. Disclosed is a dye-sensitized solar cell that can effectively avoid problems such as cell cracking and peeling of a sealing material due to a difference in thermal expansion between an electrode substrate and a metal electrode substrate, and can function stably as a battery. .

According to the present invention, an electrode substrate is provided so as to be opposed to each other, and a power generation region including an electrolyte layer and a semiconductor porous layer sensitized with a dye is provided between the electrode substrates, and the power generation In the dye-sensitized solar cell in which a sealing region made of a sealing material that is located around the region and combines both electrode substrates is formed,
Provided is a dye-sensitized solar cell in which a distance between both electrode substrates in the sealing region is set larger than a distance between both electrode substrates in the power generation region.

In the dye-sensitized solar cell of the present invention,
(1) The interval between both electrode substrates in the sealing region is set to be 10 μm or more larger than the interval between both electrode substrates in the power generation region;
(2) One electrode substrate is a metal electrode substrate and the other is a glass electrode substrate, and a step is formed on the surface of the metal electrode substrate on the glass electrode substrate side. The stop area is partitioned,
(3) As the metal electrode substrate, an aluminum substrate, a stainless steel substrate or a copper substrate is used,
Is preferred.

  In the dye-sensitized solar cell of the present invention, the interval between the metal electrode substrate and the glass electrode substrate in the sealing region is set to be larger than the interval between both electrodes in the power generation region. The thickness of the sealing material can be increased without increasing the distance between the two electrode substrates.

  That is, in the present invention, by increasing the thickness of the encapsulant, the stress absorption capacity of the encapsulant is increased, and various inconveniences caused by the difference in thermal expansion between the metal electrode substrate and the glass electrode substrate, for example, Inconveniences such as cell cracking due to thermal history and peeling of the sealing material can be effectively avoided. Specifically, as shown in an experimental example to be described later, a metal electrode substrate and a glass substrate (linear expansion coefficient: 9 ppm / ° C.) formed using an aluminum substrate (linear expansion coefficient: 23 ppm / ° C.) When the thermal cycle is applied when the difference in linear expansion coefficient between the electrode substrates is very large, the electrolyte due to cell destruction or peeling of the sealing material Liquid leakage and the like are effectively prevented, and the battery function can be maintained stably over a long period of time.

  In addition, since the above-mentioned advantage is not brought about by increasing the width of the sealing material, it is possible not only to effectively increase the area of the electrode substrate, but also between the electrode substrates in the power generation region. Since it is not necessary to increase the interval, it is possible to effectively avoid a decrease in conversion efficiency due to an increase in the thickness of the electrolyte layer.

<Battery structure>
The dye-sensitized solar cell of the present invention has the structure shown in FIG. 2, and the structure of the power generation region has substantially the same structure as the conventional dye-sensitized solar cell shown in FIG. However, it has a novel feature in the structure in the sealing region.

  That is, in the structure of FIG. 2, the dye-sensitized solar cell of the present invention has a metal electrode substrate indicated by 20 as a whole and a glass electrode substrate indicated by 30 as a whole. An electrolyte layer 40 is provided between the substrates 20 and 30, and a region where the electrolyte layer 40 is provided is a power generation region X. Moreover, the peripheral part of this electric power generation area | region X becomes the sealing area | region Y, and the peripheral part of this area | region Y, ie, the metal electrode substrate 30 and the glass electrode substrate 30, is sealed with the sealing material 50, and an electric power generation area | region. The structure prevents leakage of liquid from X (electrolyte layer 40).

  The metal electrode substrate 20 is light-impermeable and includes a metal substrate 21 and, if necessary, a reverse-electricity preventing layer 23 formed on the metal substrate 21.

The metal substrate 21 is not particularly limited as long as it is formed from a metal material having a low electrical resistance. Generally, a metal or alloy having a specific resistance of 6 × 10 ⁻⁶ Ω · m or less, such as aluminum, Iron (steel), copper, nickel, etc. are used. Further, the thickness of the metal substrate 21 is not particularly limited as long as it has a thickness enough to maintain an appropriate mechanical strength. If productivity is not taken into consideration, the metal substrate 21 may be formed on a resin film or the like, for example, by vapor deposition. Of course, the substrate such as the resin film does not need to be transparent. In the present invention, various inconveniences caused by the thermal history can be avoided even when the metal substrate 21 is made of a material having a significantly different linear thermal expansion coefficient from that of a glass substrate such as aluminum, stainless steel (SUS304), or copper. The ability to use an aluminum substrate that is particularly lightweight and inexpensive is a significant advantage of the present invention.

  The reverse current prevention layer 23 appropriately formed on the metal substrate 21 is a layer made of a metal or metal oxide having a higher resistance than that of the metal substrate 21, and prevents reverse current and provides an effective rectifying barrier. In addition, it has corrosion resistance and also has a function of preventing corrosion of the metal substrate 21 due to permeation of liquid from the electrolyte layer 40 described later. Such a reverse current preventing layer 23 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-53165, and has an appropriate composition according to the material of the metal substrate 21 by chemical conversion treatment, plating method, cladding method, or the like. The thickness is usually 1000 nm or less, particularly 5 to 500 nm, and most preferably about 5 to 100 nm.

  A dye-sensitized semiconductor porous layer 25 is formed on a portion (central portion) that becomes the power generation region X of the metal electrode substrate 20 including the metal substrate 21 and the anti-electrostatic layer 23 formed as necessary. The

  The dye-sensitized semiconductor porous layer 25 formed on the metal substrate 21 (or the reverse current prevention layer 23) has been conventionally used in dye-sensitized solar cells, and the oxide semiconductor layer is adsorbed and supported by the dye. It is a thing.

The oxide semiconductor porous layer for adsorbing and supporting the dye is, for example, an oxide of a metal such as titanium, zirconium, hafnium, strontium, tantalum, chromium, molybdenum, tungsten, or a composite oxide containing these metals, such as SrTiO _3. And a perovskite type oxide such as CaTiO ₃ , and the thickness is usually about 3 to 15 μm.

  Further, the porous layer of the oxide semiconductor needs to be porous in order to carry the dye, and for example, the relative density by the Archimedes method is 50 to 90%, particularly about 50 to 70%. It is preferable that a large surface area can be secured and an effective amount of the dye can be supported.

Such an oxide semiconductor porous layer is, for example, a paste prepared by dispersing fine particles of the above-described oxide semiconductor in an organic solvent or an organic compound having chelate reactivity, or a titanium alkoxide (for example, tetraisopropoxy titanium). It is easily formed by applying a slurry or paste dispersed in an organic solvent together with a binder component such as) on the metal substrate 21 and baking it at a temperature of 600 ° C. or lower for a time to the above-mentioned relative density. be able to. That is, by firing, the TiO ₂ gel formed by the gelation (dehydration condensation) of the binder component joins the semiconductor fine particles and becomes porous.

  The semiconductor fine particles used for forming the slurry or paste as described above should have a particle size in the range of 5 to 500 nm, particularly 5 to 350 nm from the viewpoint of making them porous. Further, as the chelate-reactive organic compound, β-diketone, β-ketoamine, and β-ketoester are representative and can be used without particular limitation as long as it is easily volatile. However, acetylacetone, which is a β-diketone, can be used. Is particularly suitable, and is preferably used in an amount of 5 to 35% by weight based on the weight of the semiconductor fine particles. Further, the titanium alkoxide as a binder component is preferably used in an amount of 10 to 60 parts by weight, particularly 20 to 50 parts by weight, per 100 parts by weight of titanium dioxide fine particles. In general, lower alcohols having 4 or less carbon atoms such as methanol, ethanol, isopropanol, n-butanol, sec-butanol, t-butanol and the like are suitable, and these organic compounds can be used without limitation. A solvent may be used independently and can also be used in the form of the mixed solvent which combined 2 or more types. The amount of the organic solvent may be used in such an amount that the slurry or paste exhibits an appropriate coating property. In general, the solid content concentration of the slurry or paste is 5 to 50% by weight, particularly 15 to 40% by weight. It is better to use it in an amount that is in the range. If the amount of solvent is too large, the slurry or paste becomes low-viscosity and it becomes difficult to form a coating layer with a stable thickness due to dripping, etc., and if the amount of solvent is small, the viscosity becomes high-viscosity and workability decreases. Because.

  The dye adsorbed on the oxide semiconductor porous layer formed as described above is adsorbed and supported by bringing the dye solution into contact with the porous layer. The contact of the dye solution is usually performed by dipping, and the adsorption treatment time (immersion time) is usually about 30 minutes to 24 hours, and after adsorption, the solvent of the dye solution is removed by drying, A dye-sensitized semiconductor porous layer 23 having a sensitizing dye adsorbed and supported on the surface and inside is formed.

The dye used can function as a sensitizing dye and has a linking group such as a carboxylate group, a cyano group, a phosphate group, an oxime group, a dioxime group, a hydroxyquinoline group, a salicylate group, and an α-keto-enol group. Those known per se are used. For example, a ruthenium complex, an osmium complex, an iron complex, etc. can be used without any limitation. Ruthenium-tris (2,2′-bispyridyl-4,4′-dicarboxylate), ruthenium-cis-diaqua-bis (2,2′-bispyridyl-4,4) in that it has a particularly broad absorption band. Ruthenium-based complexes such as' -dicarboxylate) are preferred. Such a dye solution of a sensitizing dye is prepared using an alcohol-based organic solvent such as ethanol or butanol as a solvent, and the dye concentration is usually about 3 × 10 ^{−4 to} 5 × 10 ⁻⁴ mol / l. It is good to do.

  The glass electrode substrate 30 is a light-transmitting electrode, and power is generated in the power generation region X by being irradiated with light from the substrate side. The glass electrode substrate 30 has a glass substrate 31, and a transparent conductive film 33 and an electron reducing conductive layer 35 are formed on the glass substrate 31 in this order.

  The glass substrate 31 is not particularly limited as long as it has high light transmissivity, and a glass substrate made of any glass material such as quartz glass or pyrex glass can be used. The thickness and size are appropriately determined according to the intended use of the dye-sensitized solar cell to be finally formed.

  Typical examples of the transparent conductive film 33 formed on the glass substrate 31 include a film made of an indium oxide-tin oxide alloy (ITO film), a film in which tin oxide is doped with fluorine (FTO film), and the like. An ITO film is preferable because of its high electron-reducing properties and particularly desirable characteristics as a cathode. These are formed on the glass substrate 31 by vapor deposition, and the thickness is usually about 500 nm to 700 nm.

  The electron reduction conductive layer 35 formed on the transparent conductive film 33 is generally made of a thin platinum layer and has a function of quickly transferring electrons flowing into the transparent conductive film 33 to the electrolyte layer 40. is there. Such an electron reduction conductive layer 40 is thinly formed by vapor deposition so that the average thickness thereof is about 0.1 to 1.5 nm so as not to impair the light transmittance.

  The electrolyte layer 40, which is disposed between the metal electrode substrate 20 and the glass electrode substrate 30 described above and forms the power generation region X, is a negative ion such as a cation such as lithium ion or a chlorine ion, as in a known solar cell. It is formed by various electrolyte solutions containing ions. Further, it is preferable that an oxidation-reduction pair capable of reversibly taking an oxidized structure and a reduced structure exists in the electrolyte layer 40. Examples of such an oxidized-reduced pair include an iodine-iodine compound, bromine, and the like. -A bromine compound, quinone-hydroquinone, etc. can be mentioned. Such an electrolyte layer 40 is sealed by the sealing material 50 provided in the sealing region Y located at the periphery of the power generation region X, and leakage of liquid from between the electrodes is prevented. In general, the thickness of the electrolyte layer 40 is about 10 μm or less, although it varies depending on the size of the battery finally formed.

  As the sealing material 50, various heat-sealable thermoplastic resins or thermoplastic elastomers such as low-density polyethylene, high-density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, or ethylene, Polyolefin resins such as random or block copolymers of α-olefins such as propylene, 1-butene and 4-methyl-1-pentene; ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene- Ethylene-vinyl compound copolymer resin such as vinyl chloride copolymer; Styrenic resin such as polystyrene, acrylonitrile-styrene copolymer, ABS, α-methylstyrene-styrene copolymer; polyvinyl alcohol, polyvinyl pyrrolidone, polychlorinated Vinyl, polyvinylidene chloride, vinyl chloride Nyl-vinylidene chloride copolymer, vinyl resins such as polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polymethyl methacrylate; nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, etc. Polyamide resin; Polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; Polycarbonate; Polyphenylene oxide; Cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; Starch such as oxidized starch, etherified starch, dextrin; and mixtures thereof A resin comprising, for example, is used.

  That is, the sealing material 50 is obtained by molding into a ring shape having a width corresponding to the sealing region Y by extrusion molding, injection molding, or the like using the above-described thermoplastic resin. Are heat-sealed (thermocompression bonding) in a state of being sandwiched between the metal electrode substrate 20 and the glass electrode substrate 30 arranged to face each other, whereby the metal electrode substrate 20 and the glass electrode substrate 30 are joined, Next, an injection tube is inserted into the sealing material 50, and an electrolyte solution for forming the electrolyte layer 40 is injected into the space between the metal electrode substrate 20 and the glass electrode substrate 30 through the injection tube. Thus, a dye-sensitized solar cell having the structure shown in FIG. 2 can be obtained.

  When heat-sealing the sealing material 50 formed in a ring shape, an adhesive resin such as anhydrous maleate is previously applied to the joint surface between the sealing material 50 and the metal electrode substrate 20 or the glass electrode substrate 30. The sealing material 50 can be joined by applying an unsaturated carboxylic acid-modified olefin resin graft-modified with an unsaturated carboxylic acid and heat sealing through the adhesive resin.

  In the dye-sensitized solar cell of the present invention having the above-described structure, the interval d between the metal electrode substrate 20 and the glass electrode substrate 30 in the sealing region Y is the interval between both electrode substrates in the power generation region X. It is an important feature that it is set larger than D.

  That is, as understood from FIG. 2, an annular step 27 is formed at the peripheral edge of the metal electrode substrate 20, and the surface portion in the sealing region Y is lower than the surface portion in the power generation region X. The distance d between the metal electrode substrate 20 and the glass electrode substrate 30 in the sealing region Y is the distance D between the two electrode substrates in the power generation region X by the height h of the step 27. (H = d−D).

  As understood from the above description, in the present invention, by forming the step 27 as described above, the thickness of the sealing material 50 (as compared to the case where such a step 27 is not formed) ( (corresponding to d) is formed thicker by the height h of the step, and as a result, the stress absorbing ability of the sealing material 50 is enhanced. As already described, the coefficient of thermal expansion differs between the metal electrode substrate 20 and the glass electrode substrate 30. For example, depending on the material of the metal substrate 21 or the glass substrate 31, the difference in linear expansion coefficient is extremely high. For this reason, when a thermal history is applied, thermal stress is generated between the metal electrode substrate 20 and the glass electrode substrate 30, causing cell destruction, peeling of the sealing material 50, and the like. The electrolyte solution leaks from the layer 40 and the function as a battery is impaired. However, in the present invention, since the step 27 as described above is formed and the thickness of the sealing material 50 is increased to increase the stress absorption capability, the thermal stress caused by the thermal history is effectively relaxed, Such inconvenience can be effectively prevented.

  What is important here is that the thickness t of the electrolyte layer 40 does not need to be increased when the stress absorbing ability of the sealing material 50 is increased by forming the step 27 as described above. That is, if the thickness of the sealing material 50 is simply increased without forming the step 27, the thickness t of the electrolyte layer 40 increases accordingly. However, when the thickness of the electrolyte layer 40 is increased, the light that is irradiated to the power generation region X and reaches the dye-sensitized semiconductor layer 25 is attenuated corresponding to the increase in the thickness of the electrolyte layer 40, and as a result, This leads to a decrease in conversion efficiency. In the present invention, since the stress absorbing ability of the sealing material 50 is enhanced by the formation of the step 27, the thickness of the electrolyte layer 40 is constant and does not increase, so that a reduction in conversion efficiency can be effectively avoided. Become.

  In order to increase the stress absorption capacity 50 of the sealing material 50, it is conceivable to increase the width of the sealing material 50 (corresponding to the width of the sealing region Y). In order to relieve the thermal stress caused by the coefficient difference, it is necessary to considerably increase the width, resulting in an increase in the area of the electrode. In the present invention, the area of the electrode is not increased.

  In the present invention, as means for forming the step 27 on the metal electrode substrate 20 as described above, means for removing the peripheral portion of the metal substrate 21 by etching or the like can be considered. The means of pressing the center part with a punch or the like and deforming it while holding the peripheral edge of 21 with an appropriate jig is most suitable and can be easily performed. As shown in FIG. 3, the metal substrate 21 formed in this way is such that the central portion corresponding to the power generation region X has a height of the step 27 compared to the peripheral portion corresponding to the sealing region Y. The shape is deformed so as to increase by an amount corresponding to h. In the case where the step 27 is formed by such a pressing process, when the reverse current prevention layer 23 is provided, the reverse current prevention layer 23 may be formed at any point before or after the processing.

  In the above-described example, the step 27 is formed on the metal electrode substrate 20, but a step can be formed on the glass electrode substrate 30, and further, the metal electrode substrate 20 and the glass electrode 30 A step can be formed on both. However, in order to form a step in the glass electrode substrate 30, it is necessary to cut the peripheral edge of the glass substrate 31, and therefore, the aspect in which the step 27 is formed in the metal electrode substrate 20 is most advantageous.

  In the present invention described above, the height h of the step 27 is preferably at least 0.01 mm. If this length is too short, the stress absorbing ability of the sealing material 50 cannot be sufficiently increased, and inconvenience due to the difference in thermal expansion between the metal electrode substrate 20 and the glass electrode 30 can be sufficiently prevented. It will be difficult. In this case, the upper limit value of the height h of the step 27 may be set to a value that ensures sufficient strength according to the thickness of the metal substrate 21 to be used. The width of the sealing material 50 (that is, the width of the sealing region Y) is set to an appropriate size so as not to increase the area more than necessary according to the size of the target dye-sensitized solar cell. do it.

The invention is illustrated by the following experimental example.
(Experimental example 1)
A commercially available aluminum plate (width 20 mm, length 70 mm, thickness 0.3 mm) is prepared as a metal substrate, and the aluminum plate is pressed by a punch with a width of 10 mm × length 60 mm × thickness 0.03 mm. The step was processed.
After the stepped metal substrate thus obtained was sufficiently washed and dried, the titanium oxide paste was applied to the center of the metal substrate by a screen printing method with an area of 10 mm × 60 mm, and heat-treated in an electric furnace at 420 ° C. for 30 minutes. The titanium oxide porous membrane was formed. The obtained titanium oxide porous membrane had a thickness of about 10 μm.

The titanium oxide paste has two types of commercially available TiO ₂ particles having a spherical particle size of 30 nm and a polyhedral particle size of 15 nm as a main agent, terpineol as a solvent, 60 wt% in the paste, ethyl cellulose as a binder agent, viscosity Was adjusted so as to be 5 to 15 cP.
The oxide semiconductor layer was dipped in a solution containing D149 dye manufactured by Mitsubishi Paper Industries, Ltd., which is an organic dye, for about 4 hours, and then dried to modify titanium oxide fine particles to form a negative electrode.

On the other hand, FTO having platinum formed by sputtering on a glass substrate was used as a counter electrode (positive electrode) and sealed with a sealing material made of polypropylene resin having a thickness of 50 μm.
A dye-sensitized solar cell was fabricated by sandwiching an electrolyte solution between the prepared metal electrode substrate and glass electrode substrate. As the electrolyte _solution, used was added 4-tert-butylpyridine LiI / I 2 a (0.5M / 0.025 M) to that dissolved in methoxypropionitrile.
When the conversion efficiency of the obtained solar cell was measured, the measurement area was 10 mm × 60 mm, and the following results were obtained.
Conversion efficiency: 4.0%
FF: 0.58
JSC: 10.7
VOC: 0.64

(Experimental example 2)
A commercially available aluminum plate (width 20 mm, length 70 mm, thickness 0.3 mm) was prepared as a metal substrate, and a dye-sensitized solar cell was manufactured under the same conditions as in Experimental Example 1 except that the step processing was not performed. When the conversion efficiency of the obtained solar cell was measured, it was as follows with a measurement area of 10 mm × 60 mm, which was lower than that of Experimental Example 1.
Conversion efficiency: 3.1%
FF: 0.54
JSC: 9.3
VOC: 0.62

The figure which shows the structure of a conventionally well-known dye-sensitized solar cell. The figure which shows the structure of the dye-sensitized solar cell of this invention. The figure which shows the representative example of the shape of the metal substrate used for the dye-sensitized solar cell of this invention.

Explanation of symbols

20: Metal electrode substrate 21: Metal substrate 25: Dye-sensitized porous semiconductor layer 27: Step 30: Glass electrode 31: Glass substrate 33: Transparent conductive film 35: Electron reducing conductive layer 40: Electrolyte layer 50: Sealing Material X: Power generation area Y: Sealing area

Claims (4)

An electrode substrate is provided so as to be opposed to each other, and a power generation region composed of an electrolyte layer and a semiconductor porous layer sensitized with a dye is disposed between both electrode substrates, and is positioned around the power generation region. And in the dye-sensitized solar cell in which a sealing region made of a sealing material binding both electrode substrates is formed,
The dye-sensitized solar cell, wherein an interval between the two electrode substrates in the sealing region is set larger than an interval between the two electrode substrates in the power generation region.   2. The dye-sensitized solar cell according to claim 1, wherein an interval between both electrode substrates in the sealing region is set to be 10 μm or more larger than an interval between both electrode substrates in the power generation region. One electrode substrate is a metal electrode substrate, the other is a glass electrode substrate,
The dye-sensitized solar cell according to claim 1 or 2, wherein a step is formed on the surface of the metal electrode substrate on the glass electrode substrate side, and the power generation region and the sealing region are partitioned by the step. .   The solar cell according to claim 3, wherein an aluminum substrate, a stainless steel substrate, or a copper substrate is used as the metal electrode substrate.

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