JP2007335228A - Solar cell and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell capable of filling an electrolyte without providing any special members, and without forming a part bringing about a decrease in the battery performance such as a hole, or the like for filling an electrolyte. <P>SOLUTION: The solar cell comprises: a transparent negative electrode sheet 1 having a power generation layer on the inner surface; a positive electrode sheet 3 arranged opposite to the negative electrode sheet 1; and a layer of an electrolyte 7 provided between the negative electrode sheet 1 and the positive electrode sheet 3. The peripheries of the negative electrode sheet 1 and the positive electrode sheet are bonded together. One portion of the peripheries is bonded with a biting seal while holding the layer of the electrolyte 7 in between. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solar cell and a manufacturing method thereof, and more particularly to a dye-sensitized solar cell and a manufacturing method thereof.

  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, a dye-sensitized solar cell has been proposed as a solar cell using a material other than silicon. In this type of solar cell (cell), a positive electrode base and a negative electrode base on which a semiconductor layer sensitized with a dye is formed on a transparent conductive base are attached at the periphery, It has a structure in which an electrolytic solution is filled in a gap in the center between the positive electrode base and the negative electrode base.

  In the dye-sensitized solar cell having such a structure, when visible light is irradiated from the negative electrode substrate side, the dye is excited and transitions from the ground state to the excited state, and the excited dye electrons are transferred to the negative electrode substrate. It is injected into the formed semiconductor layer and moves to the positive electrode substrate through a predetermined external circuit. The electrons that have moved to the positive electrode substrate are carried by the ions in the electrolyte and return to the semiconductor layer sensitized with the dye. Electric energy is extracted by repeating such a process.

By the way, in such a solar cell, in order to fill the electrolytic solution, for example, a member for filling the electrolytic solution is provided between the peripheral portions of the positive electrode base and the negative electrode base, and is separate from such a battery. A method of filling an electrolyte solution in a space between a positive electrode base and a negative electrode base from the above member has been proposed (Patent Document 1). Moreover, the peripheral part of a positive electrode base | substrate and a negative electrode base | substrate is sealed by heat sealing with a thermoplastic adhesive, and electrolyte solution is filled through the hole formed in the base material (positive electrode base | substrate or negative electrode base | substrate). A method has also been proposed (Patent Document 2).
JP 2002-280086 JP 2004-319112 A

  However, when a separate member is provided for filling the electrolyte solution as in Patent Document 1, it naturally increases the cost. Moreover, when forming a hole in a base material like patent document 2, the fall of the basic performance of a battery will arise.

Accordingly, an object of the present invention is to provide a solar cell that can be filled with an electrolytic solution without providing a special member and without forming a portion with a decrease in battery performance such as a hole for filling the electrolytic solution. And a manufacturing method thereof.
Another object of the present invention is to provide a method for manufacturing a solar cell that uses a biting seal by heat sealing but can effectively avoid performance degradation due to heat sealing.

According to the present invention, the first electrode substrate provided with the power generation layer on the inner surface, the second electrode substrate disposed opposite to the first electrode substrate, the first electrode substrate and the second electrode substrate. And at least one of the first electrode substrate and the second electrode substrate is transparent, and the peripheral portion between the first electrode substrate and the second electrode substrate is In the pasted solar cell,
A part of the peripheral portion is attached by a biting seal with an electrolyte layer interposed therebetween, and a solar cell is provided.

In the solar cell of the present invention,
(1) Between the first electrode substrate and the second electrode substrate, an adhesive comprising at least a temporary fixing layer and a main seal layer at a portion of the peripheral portion where the biting seal is performed. A temporary fixing layer is bonded and fixed to the first electrode substrate or the second electrode substrate without sandwiching the electrolyte layer, and the sealing layer is bitten by sandwiching the electrolyte layer. It is adhesively fixed to the second electrode substrate or the first electrode substrate by a dip seal.
(2) The temporary fixing layer is formed under a relatively low temperature and / or low pressure condition as compared to a biting seal when the seal layer is bonded and fixed to the second electrode substrate or the first electrode substrate. Be temporarily fixed to the first electrode substrate or the second electrode substrate,
Is preferred.

Further, according to the present invention, an opening is formed in the peripheral portion between the first electrode substrate having the power generation layer on the inner surface and the second electrode substrate disposed opposite to the first electrode substrate. So as to prepare a bag-like base material formed by pasting with leaving a part, filling the inside of the bag-like base material through the opening, and then sealing the In a method of manufacturing a solar cell by attaching peripheral edges of a first electrode substrate and a second electrode substrate located in an opening,
Prior to the creation of the bag-like base material, the adhesive film is temporarily fixed and sealed to the peripheral portion located at the opening of the first electrode substrate or the second electrode substrate,
While performing the main seal by biting and sealing the adhesive film into the second electrode substrate or the first electrode substrate,
The temporary fixing seal is provided under a relatively low temperature and / or low pressure condition as compared to the biting seal.

In the production method of the present invention,
(3) The adhesive film is provided with an adhesive layer composed of a temporary fixing layer and a main sealing layer. In the temporary fixing seal, the temporary fixing layer is the first electrode substrate or the second electrode. Affixed to the substrate, and the seal layer is affixed to the second electrode substrate or the first electrode substrate in the biting seal,
Is preferred.

  In the solar cell of the present invention, a part of the peripheral portion of the first electrode substrate and the second electrode substrate is attached by a biting seal with the electrolyte layer interposed therebetween. Filling with the electrolyte to form is done through the opening in the stage before the bite seal. Therefore, it is not necessary to form holes for filling the electrolytic solution in the first electrode substrate or the second electrode substrate, and performance degradation due to the formation of such holes is effectively avoided. Further, no special member for filling the electrolyte solution is provided between the peripheral portions of the first electrode substrate and the second electrode substrate. Therefore, the cost increases due to such a special member. Is also effectively avoided.

  Further, in the manufacturing method of the present invention, the peripheral portions of the first electrode substrate and the second electrode substrate arranged so as to face each other are pasted so that an opening is formed. The bag-like base material formed by attaching is prepared, and the electrolyte solution is filled through the opening of the bag-like base material, and then the main seal is inserted into the opening by a biting seal using an adhesive film. This adhesive film is temporarily fixed and sealed at the peripheral edge of one of the first electrode substrate and the second electrode substrate at the opening portion, and is sandwiched between the electrolyte layers. Sealing is performed only on one side of the adhesive film. Accordingly, it is possible to effectively suppress inconveniences such as poor adhesion and reduced workability due to the biting seal.

  Moreover, in the manufacturing method of the present invention, the temporary fixing seal of the adhesive film to the first electrode substrate or the second electrode substrate is performed under a low temperature and / or low pressure condition as compared with the main seal by the biting seal. Is called. Therefore, it is possible to effectively avoid the performance degradation of the battery due to the thermal history.

Hereinafter, the present invention will be described in detail based on specific examples shown in the accompanying drawings.
FIG. 1 shows a schematic side sectional structure of a solar cell of the present invention,
FIG. 2 shows a manufacturing process of a solar cell in the present invention,
FIG. 3 is an explanatory diagram for explaining a biting seal employed in the manufacturing process of FIG.
FIG. 4 is an explanatory diagram for explaining a comparative example of the biting seal,
FIG. 5 is a diagram showing a layer structure of an adhesive film that is preferably used for biting seals in the present invention;
FIG. 6 is a diagram showing the resistance change of the electrode substrate when the temporary fixing seal and the main seal by the biting seal are performed under the same conditions (Experimental Example 1).

  Referring to FIG. 1, the solar cell of the present invention has, for example, a peripheral portion between a rectangular negative electrode sheet 1 (first electrode substrate) and a positive electrode sheet 3 (second electrode substrate) as an adhesive layer 5. The electrolytic solution layer is formed by filling the electrolytic solution 7 in the central space.

  The negative electrode sheet 1 includes (i) a transparent substrate sheet 11, a transparent electrode layer 13 provided on the surface thereof, a semiconductor layer 15 formed in a central region on the transparent electrode layer 13, or (ii) a metal The sheet is composed of a semiconductor layer 15 formed on the surface thereof, and the surface of the semiconductor layer 15 is sensitized by the dye 17. That is, the semiconductor layer 15 sensitized by such a dye 17 becomes a power generation layer.

As the transparent substrate sheet 11, a transparent glass plate or a transparent resin film is used. Any transparent resin film can be used as long as it is transparent. For example, low-density polyethylene, polypropylene, poly-4-methyl-1-pentene, or ethylene, propylene, 1-butene, 4-methyl-1 -Polyolefin resins such as random or block copolymers of α-olefins such as pentene; ethylene-vinyl compounds such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl chloride copolymer Copolymer resin: Styrene resin such as polystyrene, acrylonitrile-styrene copolymer, ABS, α-methylstyrene-styrene copolymer; polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride Copolymer, polyacrylic acid, polymer Vinyl resins such as tacrylic acid, polymethyl acrylate and polymethyl methacrylate; polyamide resins such as nylon 6, nylon 6-6, nylon 6-10, nylon 11 and nylon 12; polyethylene terephthalate (PET), polybutylene terephthalate Polyester resin such as polyethylene naphthalate (PEN); polycarbonate; polyphenylene oxide; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; and resins made of a mixture thereof; In general, a PET film or a PEN film is preferably used from the viewpoint of strength, heat resistance, and the like. Further, the thickness and size of the transparent base sheet 11 are not particularly limited and are appropriately determined according to the use of the dye-sensitized solar cell to be finally used. In general, the thickness is It is about 10 to 500 μm.
On the other hand, the metal sheet is not particularly limited as long as it is formed from a metal material having low electrical resistance, but in general, it is preferably formed from iron such as aluminum, copper, or stainless steel. Further, the thickness is not particularly limited as long as it has a thickness that can maintain an appropriate mechanical strength. Moreover, such a metal sheet 19 may be formed in a resin film etc. by vapor deposition etc., for example.

The transparent electrode layer 13 is typically a film made of an indium oxide-tin oxide alloy (ITO film), a film in which tin oxide is doped with fluorine (FTO film), a zinc oxide film, etc., but has a low electrical resistance. Therefore, an ITO film is particularly suitable. These are formed on said transparent base material sheet 11 by vapor deposition, The thickness is about 0.5 thru | or 0.7 micrometer normally.
When a metal sheet is used, it is necessary to provide a conductive layer for preventing contact with the electrolyte solution between the metal substrate and the semiconductor layer 15 instead of the transparent electrode layer. What has a barrier property is good. The conductive layer is preferably nickel or titanium, and is made of a material having a higher resistance than that of the metal substrate. Therefore, the thickness should be as thin as possible, as long as adequate electrolytic corrosion resistance and rectifying barrier properties are ensured, and usually 5 mm to 100 μm. Degree.

The semiconductor layer 15 is a metal oxide semiconductor, 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 or CaTiO _3. In order to secure a high conversion rate, it is preferably formed of titanium dioxide. The semiconductor layer 15 is formed to be porous by applying and baking a paste prepared by dispersing the metal oxide semiconductor particles in an appropriate solvent. The metal oxide semiconductor particles to be used are preferably fine particles in view of making them porous, and the particle size is usually in the range of 5 to 500 nm, particularly 5 to 350 nm. The formed semiconductor layer 15 preferably has a thickness of about 5 to 20 μm and a semiconductor weight of about 0.001 to 0.005 g / cm ² .

  The semiconductor layer 15 is sensitized by the dye 17. For example, the dye 17 is adsorbed by applying a solution of the sensitizing dye to the surface of the semiconductor layer 15 by dipping or the like and drying it. Such sensitizing dyes are known per se, and include, for example, 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. Various dyes, specifically, acridine, azo, indigo, quinone, coumarin, merocyanine, phenylxanthene, and other organic dyes, ruthenium, osmium, and other metal complexes System dyes and the like are preferably used.

  On the other hand, the positive electrode sheet 3 (second electrode substrate) provided facing the negative electrode sheet 1 (first electrode substrate) described above faces the surface of the base sheet 21 (facing the negative electrode sheet 1). The electrode layer 23 made of platinum or the like is formed on the side).

Said base material sheet 21 may be formed with the same material as the transparent base material sheet of the negative electrode sheet 1 mentioned above, and it is preferable that it is especially formed with polyester resin films, such as PET and PEN. Moreover, the thickness of this base material sheet 21 should just have an appropriate thickness according to the use etc. of a solar cell, but generally it is a thickness of about 20 to 500 μm.
In addition, when the negative electrode sheet has the structure of the metal sheet of (ii), the base material sheet 21 must be transparent and transmit light, but in the case of the transparent electrode of (i), it needs to be transparent. There is no.

  The base sheet 21 may have a multilayer structure. For example, the above-described polyester resin film is used, and the inner surface or the outer surface is made of a barrier resin such as an ethylene-vinyl alcohol copolymer resin. A layer can be formed, or a laminated structure in which such a barrier resin is used as an intermediate layer and a polyester resin layer is used as an outer layer and an inner layer can be used.

  Moreover, you may provide the electrode layer 25 between the base material sheet 21 and the electrode layer 23 as needed. The electrode layers 23 and 25 are each formed by vapor deposition, and for example, both have a thickness of about 0.5 to 0.7 μm. In particular, when the electrode layer 23 is formed through the electrode layer 25, There is an advantage that the electrode layer 23 can be densely formed with good adhesion.

  Although the adhesive layer 5 for attaching and sealing the peripheral portions of the negative electrode sheet 1 and the positive electrode sheet 3 shown in FIG. 1 will be described later, the negative adhesive layer 5 attached by such an adhesive layer 5 is used. The distance between the electrodes of the electrode sheet 1 and the positive electrode sheet 3 (the distance between the electrode layers 13 and 23) is usually set in the range of 10 to 100 μm.

  In addition, an electrolytic solution layer is formed by filling the electrolytic solution 7 in the gap (region sealed with the adhesive layer 5) in the center between the negative electrode sheet 1 and the positive electrode sheet 3 by a process described later. Has been. As the electrolytic solution 7, various known electrolytic solutions containing a cation such as lithium ion and an anion such as chlorine ion can be used. Further, in this electrolyte solution, it is preferable that an oxidation-reduction pair capable of reversibly taking an oxidized structure and a reduced structure exists, and examples of such an oxidized-reduced pair include iodine-iodine compounds, bromine- Examples thereof include bromine compounds and quinone-hydroquinone.

  Further, the electrolytic solution 7 may be impregnated in a mesh-like electrical insulating sheet (not shown) such as paper or non-woven fabric. By such an electrical insulating sheet, the negative electrode sheet 1 and the positive electrode are provided. Electrical leakage with the sheet 3 can be reliably prevented.

  In the solar cell having the structure as described above, in the case of the structure (i), the dye 17 is excited by irradiation of visible light from the negative electrode sheet 1 side, and the electrons of the excited dye 17 enter the semiconductor layer 15. Injected. Therefore, by making the electrode layer 13 and the electrode layer 23 conductive through an external circuit, the electrons injected into the semiconductor layer 15 flow into the electrode layer 23 and are carried by the ions in the electrolytic solution 7 and again. Returning to the semiconductor layer 15 sensitized with the dye 17, electrical energy is extracted by repeating such a process and functions as a battery. In the case of the structure as shown in (i), light is irradiated from the positive electrode sheet 3 side, the dye 17 is excited through the electrolyte layer 7, and functions as a battery through the same process as described above.

  In the present invention, the solar cell having the above-described structure is manufactured by the process shown in FIG.

  That is, referring to FIG. 2, first, the negative electrode sheet 1 and the positive electrode sheet 3 described above are faced to each other and heat-sealed in three directions, thereby producing a bag-like base material indicated by 30 as a whole. 2 (a)]. In this bag-like base material 30, naturally, the power generation part (transparent electrode layer 13 and semiconductor layer 15) side formed on the negative electrode sheet 1 is the inner surface, and this power generation part is connected to the electrode side of the positive electrode sheet 3. It has come to meet.

  In the bag-shaped base material 30, the three-way seal portion is indicated by 31, and the opening portion that is not three-way sealed becomes the filling port 33. Further, from the bag-like base material 30, the electrode layer 23 of the positive electrode sheet 3 usually protrudes from the three-way seal portion 31 as the extraction electrode 35.

  The three-sided seal for producing the bag-like base material 30 is a heat seal in which a film-like frame is sandwiched between the peripheral parts of the negative electrode sheet 1 and the positive electrode sheet 3 (part corresponding to the three-way seal part 31). Is done by. The resin for forming such a frame is not particularly limited, and any adhesive resin exhibiting heat sealability can be used. For example, the various types of materials exemplified for the transparent resin film described above can be used. A thermoplastic resin or the like can be used. Usually, in order to avoid heat sealing by heating to an excessively high temperature, a softening point of about 50 to 150 ° C. is good and adhesiveness is good. Therefore, a thermoplastic resin having a functional group such as a carbonyl group such as an ethylene-vinyl acetate copolymer resin and a (meth) acrylate resin is preferable. The above-described adhesive layer 5 shown in FIG. 1 is formed from the above-described adhesive resin in the three-side seal portion 31.

  The three-way seal using such a film-like frame body uses a heat seal bar, and is generally in the range of 100 to 250 ° C. and the heat seal time is preferably about 1 to 10 seconds. Alternatively, sealing may be performed using high frequency. However, when a metal is used for the substrate, the substrate may be sealed by high frequency induction heating in addition to heat sealing by a hot plate. This is because if heat sealing is performed at a very high temperature for a long time, there is a risk that problems such as an increase in resistance of the electrodes formed on the negative electrode sheet 1 and the positive electrode sheet 3 may occur. In addition, even if the heat seal pressure is too high, cracks may occur in the electrode, so the heat seal pressure is preferably low, and a pressure of about 0.01 to 0.3 MPa is good.

  In addition, it is conceivable that the three-side seal is not performed by heat sealing using the film-like frame body as described above, for example, by using a liquid adhesive, but in this case, it takes a long time for curing. High temperature heating is required, which may cause inconveniences such as an increase in electrode resistance. In addition, the work such as coating on the three-side seal portion is troublesome and the productivity is also lowered. Therefore, it is preferable to perform three-way sealing by the heat sealing described above.

  In the present invention, the bag-like base material 30 produced as described above is filled with the electrolyte solution 7 through the filling port 33 [FIG. 2 (b)].

In the present invention, the opening of the bag-like base material 30 filled with the electrolyte solution 7 in this way, that is, the filling port 30 is sealed with the main seal by the biting seal, and the electrolyte solution 7 is enclosed. Thus, a solar cell having a structure as shown in FIG. 1 is obtained [FIG. 2 (c)]. In FIG. 2 (c), the biting seal portion closed by the biting seal is indicated by 36.
The biting seal is performed by heat sealing with the electrolyte 7 layer sandwiched therebetween, and the electrolyte sandwiched between the layers is discharged to the outside by the pressure at the time of heat sealing. Become.

  In the solar cell of the present invention obtained as described above, since the electrolytic solution 7 is sealed by the biting seal in a state filled with the electrolytic solution 7 in advance, the negative electrode sheet 1 and the positive electrode sheet 3 are electrolyzed. It is not necessary to provide a hole for filling the liquid 7, and therefore it is possible to effectively avoid a decrease in battery performance due to such a hole. Moreover, since it is not necessary to provide a special member for filling the electrolyte solution 7 between the peripheral portions of the negative electrode sheet 1 and the positive electrode sheet 3, an increase in cost due to such a member can be effectively avoided. it can. Furthermore, since the peripheral edges of the negative electrode sheet 1 and the positive electrode sheet 3 are all heat-sealed, including the bite seal, and do not employ troublesome means such as application of an adhesive, it is extremely high. It becomes possible to manufacture a solar cell with production efficiency.

  In the present invention, the biting seal is performed as shown in FIG. That is, the adhesive film 37 is fixed by heat sealing on the transparent electrode layer 13 at the peripheral edge to be the filling port 33 of the negative electrode sheet 1, and the adhesive film 37 fixed in this way is used to bite. Inclusive sealing is performed.

  As a biting seal method, for example, as shown in FIG. 4, an adhesive film 37 is inserted into a predetermined position on the periphery of the negative electrode sheet 1 and the positive electrode sheet 3, and heat sealing is performed in this state. There is a way. However, in this case, as is clear from FIG. 4, heat sealing is performed in a state where the layers of the electrolyte solution 7 are present on both sides of the adhesive film 37. That is, both the adhesive fixation between the adhesive film 37 and the negative electrode sheet 1 (transparent electrode layer 13) and the adhesive fixation between the adhesive film 37 and the positive electrode sheet 3 (electrode layer 23 or transparent electrode layer 25) are in between. It is performed by heat sealing in a state where the layer of the electrolytic solution 7 is interposed.

  Furthermore, as shown in FIG. 3, if the adhesive film 37 is bonded and fixed in advance to a predetermined position on the peripheral edge of the negative electrode sheet 1, the layer of the electrolyte solution 7 is formed on the adhesive film 37 at the time of bite sealing. It exists only on one surface, and as a result, it is possible to effectively reduce the incidence of adhesion failure.

  In the example of FIG. 3, the adhesive film 37 is fixed to the negative electrode sheet 1 side, but it is of course possible to fix the adhesive film 37 to the positive electrode sheet 3 side.

  Further, in the present invention, the adhesive fixing of the adhesive film 37 to the negative electrode sheet 1 side (or the positive electrode sheet 3 side) as shown in FIG. 3 is performed by a temporary fixing seal. This temporary fixing seal is a heat seal performed under relatively low temperature and / or low pressure conditions as compared with the main seal such as a biting seal or a three-way seal, and the adhesive film 37 is removed by such a temporary fixing seal. By temporarily fixing to the negative electrode sheet 1 (or positive electrode sheet 3) side, it is possible to effectively avoid performance degradation due to the occurrence of cracks due to the thermal history and pressure of the solar cell.

  See FIG. In FIG. 6, in Experimental Example 1 to be described later, the adhesive film 37 is inserted into the periphery of the negative electrode sheet 1 and the positive electrode sheet 3 (between the transparent electrode layer 13 and the electrode layer 23), and heat sealing is performed twice. FIG. 6 is a diagram showing changes in resistance values of the negative electrode sheet 1 (transparent electrode layer 13) and the positive electrode sheet 3 (electrode layer 23) in comparison with the resistance values before heat sealing is performed, The heat seal conditions are set to the same conditions as the main seal (temperature: 190 ° C., pressure: 0.3 MPa, time: 10 seconds) such as a bite seal. According to the experimental result of FIG. 6, when the number of times of heat sealing is one for the same part, the resistance values of the transparent electrode layer 13 and the electrode layer 23 are not increased so much, but the heat sealing is performed twice. Then, it can be seen that these resistance values increase rapidly. That is, when the adhesive film 37 is adhered and fixed to the negative electrode sheet 1 side or the positive electrode sheet 3 side by heat sealing, and further the main sealing such as the biting seal is performed, the heat sealing is performed twice. From the experimental results shown in FIG. 6, the resistance value is increased and the performance of the solar cell is sometimes lowered.

  In such a case, in the present invention, as described above, the adhesive fixing of the adhesive film 37 to the negative electrode sheet 1 side or the positive electrode sheet 3 side is performed at a lower temperature than the present seal such as a biting seal. By performing temporary fixing by heat sealing under low pressure conditions, it is possible to effectively avoid the increase in resistance value as described above.

  In the present invention, the temporary fixing seal and the biting seal as described above are preferably performed under the following conditions.

  For example, the bite seal avoids thermal degradation of the transparent electrode layer 13 and the electrode layer 23, and has the same heat seal temperature (100 to 250 ° C.) and heat seal time (about 1 to 10 seconds) as the three-way seal described above. ). In this case, it is preferable that the heat seal pressure is as small as possible, as in the case of the three-way seal. However, in the case of the biting seal, it is necessary to discharge the layer of the electrolyte solution 7 sandwiched between them. Therefore, it is preferable that the heat seal pressure is slightly higher than that of the three-way seal, and it is usually preferable to set the pressure to about 0.3 to 2.5 MPa. The adhesive film 37 is firmly fixed to the negative electrode sheet 1 (transparent electrode layer 13) and the positive electrode sheet (electrode layer 23) by the biting seal under such conditions, and the electrolytic solution 7 is enclosed.

  On the other hand, the temporary fixing seal that is performed prior to the above-described biting seal is performed under a low temperature condition as compared with the above-mentioned biting seal, but if the temperature condition of the biting seal is close, the resistance increase suppressing effect is reduced. Therefore, it is usually preferable to set the heat seal temperature in the range of 50 to 150 ° C. Further, the heat sealing time and the heat sealing pressure are determined depending on the material of the adhesive film 37 to be used. The layer 13) or the positive electrode sheet (electrode layer 23) may be selected temporarily. Generally, it is set to the same heat seal time and heat seal pressure as the three-way seal.

  The adhesive film 37 used in the present invention may basically be formed from the same heat-sealable adhesive resin as the frame used for three-way sealing, but heat sealing under low temperature conditions. The adhesive resin has a relatively low softening point and preferably has a softening point of 50 to 150 ° C., and is particularly suitable for metals such as the transparent electrode 13 and the electrode layer 23. Highly ethylene-vinyl acetate copolymer resin and (meth) acrylate resin are preferable.

  In addition, as shown in FIG. 5, the adhesive film 37 has a multilayer structure having a laminated film having a two-layer structure of the temporary fixing layer 50 and the main seal layer 51 or a resin having excellent film forming properties. Also good. That is, the temporary fixing layer 50 side may be temporarily fixed to the negative electrode sheet 1 or the positive electrode sheet 3 by the temporary fixing seal described above, and the main seal layer 51 may be the main seal side by the biting seal. As described above, by separating the function of the adhesive film 37, it is possible to ensure good adhesive strength by the temporary fixing seal or the biting seal.

  In such a multi-layered adhesive film 37, the heat-sealable thermoplastic resin constituting the seal layer 51 is such that it melts and softens when heated during biting and seals, and discharges the electrolyte in the middle. It is preferable to have a softening point in the range of 50 to 150 ° C., like the adhesive resin that constitutes the frame used for the three-way seal described above. In addition, as the adhesive resin constituting the temporary fixing layer 50, the electrolyte solution is not sandwiched therebetween, so that it is not necessary to discharge the electrolyte solution as in the present seal layer 51, and heat sealing at a low temperature of 50 to 150 ° C. Resins that can be temporarily fixed are suitable.

In addition, it is preferable that the seal layer 51 and the temporary fixing layer 50 are formed of the same kind of heat-sealable thermoplastic resin in order to avoid peeling between the main seal layer 51 and the temporary fixing layer 50. . Further, when the seal layer 51 and the temporary fixing layer 50 are formed of different types of thermoplastic resins, at least one of them is ethylene-vinyl acetate in order to avoid peeling of both layers and ensure high adhesive strength. A functional group-containing thermoplastic resin such as a copolymer resin or a (meth) acrylate resin is suitable. In this case, the temporary fixing layer 50 is most preferably formed of a functional group-containing thermoplastic resin. Is preferable in that it can be satisfactorily bonded and fixed to the negative electrode sheet 1 (transparent electrode layer 13) or the positive electrode sheet (electrode layer 23) by heat sealing (temporary fixing) at a low temperature. Further, the temporary fixing layer 50 may be blended with a resin having a low softening point, an adhesive, or the like, thereby enabling temporary bonding at a low temperature. These laminated adhesive films 37 can be easily obtained by a known method such as co-extrusion or sandwich lamination.

  The thickness of the thermoplastic resin frame used for the adhesive film 37 and the three-sided seal described above is the distance between the electrodes (electrodes) of the negative electrode sheet 1 and the positive electrode sheet 3 after heat sealing as described for the adhesive layer 5. The distance between the layers 13 and 23 may be in the range of 10 to 100 μm. In addition, regarding the laminated adhesive film 37, the temporary fixing layer 50 may be thinner than the main seal layer 51, and may be, for example, about 1 to 30 μm thick before heat sealing.

  The solar cell of the present invention obtained by the method as described above effectively avoids inconveniences such as increased resistance due to the biting seal, and is manufactured with extremely high productivity.

  The invention is illustrated by the following experimental example.

<Experimental example 1>
Two ITO films (those using PEN as the base material, 125 μm thick, manufactured by Tobi Co., Ltd.) are stacked, and a sample with a 50 μm thick adhesive (Nucrel N1525, manufactured by Mitsui DuPont) is prepared between them. did.
This sample was pressed at a pressure of 0.3 MPa for 10 seconds in order to see the change in surface resistivity with the number of heat seals.
Before applying pressure, what was pressed once, what was pressed twice, and the surface resistivity measured at the same place for each were shown in FIG.

<Experimental example 2>
The adhesive was put on an ITO film (same as that used in Experimental Example 1), and temporarily placed on a heat plate set at 70 ° C., thereby temporarily fixing the adhesive. Thereafter, another ITO film was stacked and pressed at a pressure of 0.3 MPa for 10 seconds.
The adhesive used here has a two-layer structure of Nucrel (N1525) as the sealing layer and Admer (NE058, manufactured by Mitsui Chemicals) as the temporary fixing layer. (N1525) is blended.
The surface resistivity at the same place was measured before the adhesive was temporarily fixed and after the pressure was applied. It was found that the surface resistivity of both the lower substrate and the upper substrate was 1.001, showing almost no change (the initial surface resistivity was 1). Thus, it was found that the electrolytic solution can be sealed without affecting the base material by the method of temporary fixing and main sealing.

The figure which shows the general | schematic side cross-section of the solar cell of this invention. The figure which shows the manufacturing process of the solar cell in this invention. Explanatory drawing for demonstrating the biting seal employ | adopted as the manufacturing process of FIG. Explanatory drawing for demonstrating the comparative example of a biting seal. The figure which shows the laminated constitution of the adhesive film used suitably for a biting seal in this invention. The diagram (experimental example 1) which shows the resistance change of an electrode substrate when performing a temporary fixing seal and this seal | sticker by a biting seal on the same conditions.

Explanation of symbols

1: Negative electrode sheet 3: Positive electrode sheet 7: Electrolytic solution 13: Transparent electrode layer 23: Opaque electrode 30: Bag-shaped base material 31: Three-way seal part 33: Filling port 35: Extraction electrode 36: Biting seal part 37: Adhesive film 50: Temporary fixing layer 51: Main seal layer

Claims (5)

Provided between the first electrode substrate having the power generation layer on the inner surface, the second electrode substrate disposed opposite to the first electrode substrate, and the first electrode substrate and the second electrode substrate. The electrolyte layer is formed, and at least one of the first electrode substrate and the second electrode substrate is transparent, and the periphery of the first electrode substrate and the second electrode substrate is attached to the sun. In batteries,
A part of said peripheral part is affixed by the biting seal on both sides of an electrolyte solution layer.   Between the first electrode substrate and the second electrode substrate, an adhesive layer composed of at least a temporary fixing layer and a main seal layer is provided in a portion of the peripheral portion where the biting seal is performed. The temporary fixing layer is bonded and fixed to the first electrode substrate or the second electrode substrate without sandwiching the electrolyte layer, and the seal layer is formed by a biting seal sandwiching the electrolyte layer. The solar cell according to claim 1, wherein the solar cell is bonded and fixed to the second electrode substrate or the first electrode substrate.   The temporary fixing layer is formed on the first electrode under relatively low temperature and / or low pressure conditions as compared to the biting seal when the seal layer is bonded and fixed to the second electrode substrate or the first electrode substrate. The solar cell according to claim 2, which is temporarily fixed to the substrate or the second electrode substrate. Leave a part of the periphery of the first electrode substrate having the power generation layer on the inner surface and the second electrode substrate disposed opposite to the first electrode substrate so that an opening is formed. A bag-like base material formed by pasting and filling the inside of the bag-like base material with the electrolyte through the opening, and then the first seal located in the opening by the seal. In the method of manufacturing a solar cell by pasting the periphery of the electrode substrate and the second electrode substrate,
Prior to the creation of the bag-like base material, the adhesive film is temporarily fixed and sealed to the peripheral portion located at the opening of the first electrode substrate or the second electrode substrate,
While performing the main seal by biting and sealing the adhesive film into the second electrode substrate or the first electrode substrate,
The method of manufacturing a solar cell, wherein the temporary fixing seal is performed under a relatively low temperature and / or low pressure condition as compared with the biting seal.   The adhesive film is provided with an adhesive layer composed of a temporary fixing layer and a main sealing layer, and the temporary fixing layer is attached to the first electrode substrate or the second electrode substrate in the temporary fixing seal. The method for manufacturing a solar cell according to claim 4, wherein the main sealing layer is attached to the second electrode substrate or the first electrode substrate when the biting seal is applied.

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