JP4046819B2 - Photovoltaic element manufacturing method - Google Patents

Description

【００２０】
【発明の効果】
以上説明したように、本発明によれば、特性的に全く問題がなく、かつ外観も良好な光起電力素子を容易に製造することができる。
【図面の簡単な説明】
【図１】本発明の被覆層を設けた集電電極の構成を模式的に示す断面図である。
【図２】本発明のアモルファスシリコン系光起電力素子の構成を模式的に示す断面図である。
【図３】本発明の真空加熱装置を模式的に示す断面図である。
【図４】光起電力素子に、コートワイヤー両端を固定した状況を示す模式図である。
【図５】実施例１に係る光起電力素子の製造方法の概略図である。
【図６】比較例１に係る光起電力素子の製造方法の概略図、および集電電極の形成状態を示す概略図である。
【符号の説明】
１００，４０２，５００，５０３ コーティングワイヤー
１０１ 金属ワイヤー
１０２ バリヤ層
１０３ 接着層
２０１ 基板
２０２ 下部電極
２０３，２１３，２２３ ｎ型半導体層
２０４，２１４，２２４ ｉ型半導体層
２０５，２１５，２２５ ｐ型半導体層
２０６ 透明導電膜
２０７ 集電電極
３０１ 加熱板兼下部チャンバー
３０２ ヒーター
３０３，４０１ 光起電力素子
３０４，３０８ 排気口
３０５ 樹脂シート１
３０６ 樹脂シート２
３０７ 上部チャンバー
４０３ 粘着性材料
５０１ エッチングライン
５０２ 両面テープ
５０４ バスバー[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a photovoltaic device.
[0002]
[Prior art]
BACKGROUND ART A photoelectric conversion element (photovoltaic element) that generates an electromotive force by making light incident is used in various fields. In particular, in recent years, it has been used as a solar cell as a source of clean energy because of increasing interest in environmental problems.
As such solar cells, crystalline solar cells using single crystal silicon or polycrystalline silicon, amorphous solar cells using amorphous silicon, and compound semiconductor solar cells are known. .
Among these solar cells, amorphous silicon solar cells, although the conversion efficiency is not as good as that of crystalline solar cells, can be manufactured at low cost, can easily be increased in area, and operate with thin films because of their large light absorption coefficient. It has been noticed, researched, and actually used because it has excellent characteristics not found in crystalline solar cells. However, it has not yet spread. One reason is that the manufacturing cost is relatively high. Solutions to this problem include: (i) efficient use of the power generation area, (ii) reduction of connection member costs by reducing the number of connection points, and reduction of labor costs for connection, and (iii) of the photoelectric conversion layer Reduction of manufacturing costs. In order to achieve these items, it is essential to increase the area of the solar cell.
By the way, as a configuration of an amorphous silicon solar cell, for example, a structure in which a back electrode, a semiconductor layer, and a light receiving surface electrode are deposited in this order on a conductive substrate made of stainless steel or the like is known. It is formed of a transparent conductive oxide. Further, a current collecting electrode for collecting current is formed on the surface of the light receiving surface electrode. Since the current collecting electrode is provided on the light incident surface side of the solar cell, the area of the current collecting electrode becomes a so-called shadow loss, and the effective area contributing to power generation of the solar cell is reduced. For this reason, a current collection electrode is formed in a comparatively thin shape.
[0003]
In particular, as described above, when the area of the solar cell is increased for the purpose of cost reduction, the length of the collecting electrode is also increased. It is required to design the cross-sectional shape.
As a material that satisfies this requirement, for example, as disclosed in US Pat. No. 4,260,429, an electrode in which a metal wire is coated with a polymer containing conductive particles has been proposed. According to the proposal, since a metal wire such as copper having good conductivity is used, even when a long collecting electrode is formed, the electrical resistance loss is small, and the aspect ratio can be 1: 1, so the shadow loss is also small. be able to.
In addition, in the above-mentioned US Patent Publication, it is described that a wire can be bonded by a simple method using a conductive adhesive disposed around a coated wire, for example, a method of bonding by heat or pressure. Is shown, but no specific device or technique is shown.
Japanese Patent Application Laid-Open No. 7-335921 discloses a method using heat and pressure for installing a metal wire covered with at least one layer of a conductive adhesive on a photovoltaic element. According to the method described in the publication, heat / pressure can be uniformly applied to a metal wire that can serve as a collecting electrode, and the adhesion loss can be improved and at the same time the shadow loss can be reduced.
[0004]
[Problems to be solved by the invention]
In the method described in the above-mentioned publication, adhesion is performed by heating / pressurization in a state where the covering wire is placed on the collecting electrode forming position of the photovoltaic element. In this method, both ends are completely fixed. When the coated wire is thermally expanded at the time of heating, there is a problem that the length becomes longer than a desired wire length and a meandering phenomenon of the wire occurs.
Moreover, there is also a problem that the appearance obtained thereby is impaired. In an extreme case, the meandering wire protrudes from the predetermined region and is adhered to the outside of the effective region of the solar cell, which may cause a characteristic problem that the solar cell is short-circuited. is there.
An object of the present invention is to overcome these problems and provide a method for producing a photovoltaic device having a good appearance and excellent production stability.
[0005]
[Means for Solving the Problems]
The present invention, which solves the above-mentioned problems in the prior art and achieves the above object, is a method for producing a photovoltaic device having a current collecting electrode made of a metal wire coated with a conductive resin. Only the both ends of the wire are fixed to a part of the photovoltaic element, and then the whole part of the metal wire is bonded onto the photovoltaic element surface while the metal wire is thermally expanded by heating and pressurization. It is characterized by that. The photovoltaic element has flexibility.
The both ends of the metal wire are fixed to the photovoltaic element using an adhesive material. As the adhesive material, a double-sided tape is preferably used. The heat treatment after fixing the metal wire to the photovoltaic element using the adhesive material is performed in the range of 150 ° C. from the softening temperature of the conductive resin layer covering the metal wire. Moreover, the pressure treatment after fixing as described above is 1 kg / cm. ² To 10kg / cm ² It is performed by pressurization in the range of
[0006]
[Action]
As a result of the examination by the present inventors, as described above in the prior art, the meandering phenomenon of the wire is caused by heating / heating with both ends of the wire of a desired length completely fixed. It has been found that there is a cause in that the wire is thermally expanded and adhered to the photovoltaic element in a state where the length is extended by performing the pressure.
As a result of investigations by the present inventors through experiments to solve these problems, it has been found that the following effects can be obtained according to the present invention having the above-described configuration.
(1) Both ends of a metal wire shorter than the desired length are fixed to the photovoltaic element, and then heated and pressurized to bond the metal wire in a state of being stretched to a desired length by thermal expansion. And the excess of the wire will not come out. As a result, the meandering phenomenon of the wire can be prevented.
(2) Since the photovoltaic element itself is flexible, the photovoltaic element is curved when fixing both ends of a metal wire shorter than the desired length to a part of the photovoltaic element. Therefore, the desired state can be easily fixed.
(3) By fixing both ends of the metal wire with an adhesive material, when fixing a plurality of metal wires, the length variation of the metal wires can be absorbed by the viscosity.
(4) Since the adhesive material is a double-sided tape, the manufacturing process can be simplified.
(5) Since the heat for fixing the metal wire is in the range of the softening temperature of the conductive resin layer to 150 ° C., excessive spreading of the conductive adhesive can be suppressed, and high characteristics with small shadow loss. The photovoltaic element can be obtained.
(6) The pressure for fixing the metal wire is 1 kg / cm ² To 10kg / cm ² By setting it as this range, while being able to suppress the excessive spread of a conductive adhesive material, the stable adhesive strength can be obtained.
[0007]
Embodiment Example
In the following, embodiments of the present invention will be described. The present invention is not limited to these exemplary embodiments.
[0008]
[Collector electrode]
FIG. 1 shows a metal wire 100 coated with a conductive resin layer. The metal wire 101 that constitutes the current collecting electrode 100 is preferably one that is industrially stably supplied as a wire, and the material of the metal body that forms the metal wire has a specific resistance of 10 ^-Four It is desirable to use a metal of Ωcm or less. For example, materials such as copper, silver, gold, platinum, aluminum, molybdenum, and tungsten are preferably used because of their low specific resistance. Among these, copper is desirable because it has low electrical resistance and is inexpensive. The metal wire may be an alloy of these metals.
If desired, a thin metal layer may be formed on the surface of the metal wire for the purpose of preventing corrosion, preventing oxidation, improving adhesion with a conductive resin, improving electrical conduction, and the like. As the surface metal layer, for example, silver, palladium, an alloy of silver and palladium, a noble metal that is not easily corroded such as gold, or a metal having good corrosion resistance such as nickel or tin can be used. Especially, since gold, silver, and tin are not easily affected by humidity and the like, they are preferably used as the metal layer. As a method for forming the metal layer, for example, a plating method or a cladding method is preferably used. Moreover, you may coat the conductive resin produced by disperse | distributing the said metal to resin as a filler. The thickness of the coat is determined as desired. For example, in the case of a metal wire having a circular cross section, a thickness of 1% to 10% of the diameter is suitable. The specific resistance of the metal layer is 10 in consideration of the effect of electrical continuity, corrosion resistance, and metal layer thickness. ^-6 Ωcm or more and 100 Ωcm or less is suitable.
The cross-sectional shape of the metal wire is preferably circular, but it may be rectangular and is appropriately selected as desired. The diameter of the metal wire is selected and set so that the sum of the electrical resistance loss and the shadow loss is minimized. Specifically, for example, a copper wire having a diameter of 25 μm to 1 mm is preferably used. It is done. More preferably, an efficient photovoltaic device can be obtained by setting the thickness to 25 μm to 200 μm. If it is thinner than 25 μm, the wire is easily cut and difficult to manufacture, and the electrical loss increases. On the other hand, when the thickness is 200 μm or more, the shadow loss becomes large, or the surface of the photovoltaic element becomes large, so that the filler such as EVA must be thickened when the surface is covered.
The metal wire can be produced by molding to a desired diameter with a known wire drawing machine. The metal wire that has passed through the wire drawing machine is hard, but may be annealed by a known method according to desired properties such as easiness of elongation and easiness of bending, and may be made soft.
[0009]
In the present invention, as the conductive resin for coating the metal wire, one obtained by dispersing conductive particles and a polymer resin is used. The polymer resin is preferably a resin that easily forms a coating on a metal wire, has excellent workability, has flexibility, and has excellent weather resistance. Specifically, a thermosetting resin such as a urethane resin, an epoxy resin, a phenol resin, a polyvinyl formal resin, an alkyd resin, or a resin obtained by modifying these can be used as a suitable material. In particular, urethane resins, epoxy resins, and phenol resins are used as insulating coating materials for enameled wires, and are excellent materials in terms of flexibility and productivity. Moreover, it is also suitably used as a current collecting electrode material for photovoltaic elements in terms of moisture resistance and adhesiveness.
In addition, thermoplastic resins such as butyral resin, phenoxy resin, polyamide resin, polyamideimide resin, melamine resin, butyral resin, acrylic resin, styrene resin, polyester resin, and fluororesin can also be used. Among these, butyral resin, phenoxy resin, polyamide resin, and polyamideimide resin are excellent materials in terms of flexibility, moisture resistance, and adhesiveness, and are suitably used as the material for the collecting electrode of the photovoltaic element.
The conductive particles are pigments for imparting conductivity, and specific materials include carbon black, graphite, and the like. ₂ O _Three , TiO ₂ , SnO ₂ , ITO, ZnO, and oxide semiconductor materials obtained by adding an appropriate dopant to the above materials are preferably used. The particle size of the conductive particles needs to be smaller than the thickness of the coating layer to be formed. However, if the particle size is too small, the resistance at the contact point between the particles increases, and a desired specific resistance cannot be obtained. For these reasons, the average particle size of the conductive particles is preferably 0.02 μm to 15 μm. Further, two or more different kinds of conductive particles may be mixed to adjust the specific resistance and the degree of dispersion in the conductive resin. In addition, ITO, In ₂ O _Three , TiO ₂ , SnO ₂ Translucent property may be imparted by using a material such as ZnO. Among these, particularly high translucency can be achieved by using ITO.
[0010]
The conductive particles and the polymer resin are mixed at a suitable ratio in order to obtain a desired specific resistance, but when the conductive particles are increased, the specific resistance is lowered, but the ratio of the resin is reduced, so that the coating film is used as a coating film. Stability deteriorates. Further, when the resin is increased, the contact between the conductive particles becomes poor and the resistance is increased. Therefore, a suitable ratio is appropriately selected depending on the polymer resin to be used, conductive particles, and desired physical property values. Specifically, a favorable specific resistance can be obtained by setting the conductive particles to about 5% to 95% by volume. The specific resistance of the conductive resin is a resistance that can be ignored for collecting the current generated by the photovoltaic element, and it is necessary to have an appropriate resistance value so as not to cause a shunt. Specifically, about 0.01 to 100 Ωcm is preferable. This is because the barrier function for preventing shunts decreases when the resistance is 0.01 Ωcm or less, and the electrical resistance loss increases when the resistance is 100 Ωcm or more. When mixing the conductive particles and the polymer resin, an ordinary dispersing device such as a three-roll mill, a paint shaker, or a bead mill can be used. In order to improve the dispersion, a known dispersant may be added as desired. Further, it may be diluted with an appropriate solvent for adjusting the viscosity of the conductive resin during or after dispersion.
[0011]
In the present invention, in the configuration of the current collecting electrode 100 shown in FIG. 1, the first resin layer 102 provided in contact with the metal wire 101 prevents moisture from penetrating into the metal wire and The barrier layer has a function of preventing corrosion and preventing metal ion migration from the metal wire. As the polymer resin contained in the conductive resin constituting the first resin layer, a resin having relatively little moisture permeability among the above-described resins is preferably used. That is, a urethane resin, an epoxy resin, a phenol resin, or a thermosetting resin obtained by modifying these is preferable. These resins are preferably sufficiently cured after coating. The thickness of the first resin layer 102 varies depending on the diameter of the metal wire 101 and desired characteristics. For example, if the metal wire 101 is 100 μm, the first resin layer 102 has no pinhole and functions as a barrier layer. It is preferably about 1 to 15 μm in order to be sufficient and prevent shadow loss from occurring extremely. When the thickness is 1 μm or less, it is difficult to coat uniformly, pinholes are generated, and the function as a barrier layer becomes insufficient. On the other hand, if the thickness is 15 μm or more, the coating layer is easily peeled off or the shadow loss becomes too large, which is not preferable.
The second resin layer 103 is an adhesive layer having a function of adhering and fixing the collecting electrode to the semiconductor layer or the transparent electrode and a function of collecting current. As the polymer resin contained in the conductive resin constituting the second resin layer 103, a resin having good adhesion and good flexibility among the above-described resins is preferably used. That is, a urethane resin, an epoxy resin, a phenol resin, or a thermosetting resin or a thermoplastic resin obtained by modifying these can be used as a suitable material. In particular, a urethane resin is preferably used because it is a resin that easily adjusts the crosslinking density. These resins are preferably left in an uncured state after coating, and are cured after undergoing an adhesion process. Therefore, it is preferable that the curing agent used for the curing is a blocked isocyanate. The blocked isocyanate has a mechanism in which curing proceeds by heating to the dissociation temperature of the isocyanate group of each blocked isocyanate. Therefore, by drying at a temperature lower than the dissociation temperature, the contained solvent is completely removed, and the tackiness and tackiness are lost, so that the coil can be wound on a reel and stored. Moreover, since the curing does not proceed unless heat higher than the dissociation temperature of the isocyanate is applied during storage, a uniform and sufficient adhesive force can be obtained when forming the collecting electrode.
The thickness of the second resin layer 103 varies depending on the diameter of the metal wire 101. For example, if the metal wire 101 is 100 μm, the second resin layer 103 has no pinhole, has a sufficient function as an adhesive layer, and is a shadow. A thickness of about 5 to 30 μm is preferable in order not to cause loss extremely.
As a method for coating the metal wire with the conductive resin, a normal enameled wire coating method can be preferably used. Specifically, the conductive resin has an appropriate viscosity. Then, the metal wire is coated with a roll coater or the like, passed through a die for forming a desired thickness, and then dried and thermally cured in a heating furnace.
In FIG. 1, the case where the barrier layer (102) and the adhesive layer (103) made of a conductive resin are formed around the metal wire 101 has been described. However, the present invention is not limited to this. Alternatively, the adhesive layer (103) may be directly formed.
[0012]
[Photovoltaic element]
As the photovoltaic element used in the present invention, a single crystal, polycrystalline or amorphous silicon-based photovoltaic element (solar cell), a photovoltaic element (solar cell) using a semiconductor other than silicon, a Schottky junction type It can be a photovoltaic element (solar cell). However, below, the case of an amorphous silicon photovoltaic element (solar cell) is demonstrated among these photovoltaic elements.
2A to 2C are schematic cross-sectional views of an amorphous silicon-based photovoltaic element (solar cell) in which light is incident from the side opposite to the substrate. In the figure, 201 is a substrate, 202 is a lower electrode, 203, 213 and 223 are n-type semiconductor layers, 204, 214 and 224 are i-type semiconductor layers, 205, 215 and 225 are p-type semiconductor layers, and 206 is a transparent conductive film. , 207 represent current collecting electrodes.
In the case of the amorphous silicon-based photovoltaic element (solar cell) shown in FIG. 2, that is, a thin-film photovoltaic element (solar cell), the substrate 201 is required, and the substrate is an insulating or conductive substrate. Used. A metal substrate such as stainless steel or aluminum is preferably used as the conductive substrate, and also serves as a back electrode. When an insulating substrate such as glass, polymer resin, or ceramic is used, a metal such as chromium, aluminum, or silver is vapor-deposited on the substrate to form a back electrode. The lower electrode 202 is one electrode for taking out the electric power generated in the semiconductor layers 203, 204, 205, 213, 214, 215, 223, 224, and 225, and works to be in ohmic contact with the semiconductor layer 203. It is required to have a function. As the constituent material of the lower electrode, metals such as Al, Ag, Pt, Au, Ni, Ti, Mo, W, Fe, V, Cr and Cu; for example, alloys of these metals such as nichrome; SnO ₂ , In ₂ O _Three , ZnO, ITO and other transparent conductive oxides (TCO). The surface of the lower electrode 202 is preferably smooth, but may be textured when causing irregular reflection of light. Further, when the substrate 201 is conductive, the lower electrode 202 is not necessarily provided. The lower electrode 202 can be formed by a known method such as plating, vapor deposition, or sputtering.
The amorphous silicon semiconductor layer is not only a single structure (see FIG. 2A) having an n layer 203, an i layer 204, and a p layer 205, but also a double structure in which pin junctions or pn junctions are stacked (see FIG. 2B). A triple configuration (see FIG. 2C) is also preferably used.
In particular, as a semiconductor material constituting the i layers 204, 214, and 224, in addition to a-Si, so-called group IV and group IV amorphous silicon semiconductors such as a-SiGe and a-SiC can be cited. As a method for forming the amorphous silicon semiconductor layer, a known method such as an evaporation method, a sputtering method, a high-frequency plasma CVD method, a microwave plasma CVD method, an ECR method, a thermal CVD method, or an LPCVD method is used as desired. As the film forming apparatus, a batch type apparatus or a continuous film forming apparatus can be used as desired.
The transparent conductive film 206 is necessary when the semiconductor layer has a high sheet resistance like amorphous silicon, and needs to be transparent in order to be positioned on the light incident side. The material of the transparent conductive film 206 is SnO ₂ , In ₂ O _Three , ZnO, CdO, CdSnO _Four Metal oxides such as ITO are used.
[0013]
【Production method】
An example of an apparatus suitable for carrying out the method for producing a current collecting electrode of the present invention is shown in FIG.
FIG. 3 is a schematic cross-sectional view of a heating apparatus using a vacuum system. In FIG. 3, 301 is a heating plate and lower chamber, 302 is a heater, 303 is a photovoltaic device, 304 is an exhaust port disposed in the lower chamber 301, 305 is a resin sheet 1, 306 is a resin sheet 2, and 307 is An upper chamber 308 indicates an exhaust port disposed in the upper chamber. In the apparatus of FIG. 3, the photovoltaic element 303 is heated by the heating plate / lower chamber 301, and at the same time, the pressure is applied by the resin sheets 1 and 2 to perform bonding.
The heating plate / lower chamber 301 is for heating the photovoltaic element. A thermocouple (not shown) is installed in the heating plate / lower chamber, and a control system (not shown) for performing temperature control by feeding back the temperature measured by the thermocouple is provided.
A heater 302 is disposed below the heating plate / lower chamber 301, and the heat of the heater 302 is transmitted to the photovoltaic element 303 through the heating plate / lower chamber 301.
The upper chamber 307 can move up and down, and two resin sheets 305 and 306 are installed in the lower part thereof.
At the same time that the photovoltaic element 303 is placed on the heating plate 301, the upper chamber 307 starts to descend, and the periphery is sealed at the descending end, and the photovoltaic element is surrounded by a heating plate and a resin film. A space is formed. At that step, air is drawn from the exhaust port 304 of the heating plate / lower chamber 301 and the sealed space is evacuated, so that the resin sheets 305 and 306 pressurize the collecting electrode of the photovoltaic element in the element direction. The current collecting electrode is adhered on the element.
The resin sheet 305 is for maintaining a vacuum and applying a uniform pressure, and a film having excellent heat resistance and durability is used. Specifically, materials having elasticity such as silicon rubber, fluorine rubber, neoprene rubber, etc. are preferably used. The thickness of the resin sheet 305 is designed as desired, but is preferably about 500 μm to 2 mm.
The resin sheet 306 prevents the conductive adhesive of the collecting electrode from adhering to the resin sheet 305 and prevents oil or the like that comes out when the resin sheet 305 is heated from adhering to the photovoltaic element. For prevention, it is used as desired. Specifically, a known polymer film such as PTFE, ETFE, or PFA having a thickness of about 100 μm is used. Further, in order to improve the strength, these materials may be impregnated with glass fibers.
[0014]
The pressure applied to the collecting electrode is determined by the degree of vacuum around the photovoltaic element and the hardness of the resin film, but the pressure described here is the pressure applied immediately above the collecting electrode, The value is 1.0-5kg / cm ² Is desirable. 1.0 kg / cm ² In the following cases, there is a problem that the conductive adhesive softened by heat is not pressurized so much that the adhesion area with the photovoltaic element is reduced and the series resistance is increased. 5kg / cm ² In the above case, there is a problem that the conductive adhesive softened by heat is excessively crushed and spreads widely, resulting in a large shadow loss.
The heating temperature of the collecting electrode is preferably in the temperature range from the softening temperature of the conductive adhesive to 150 ° C. In this temperature range, the spread of the adhesive is further suppressed, and a high-performance photovoltaic element with small shadow loss can be obtained.
As the length of the metal wire when forming the current collecting electrode, a metal wire having a length shorter than a desired length is used. The degree of shortness is determined by the thermal expansion coefficient of the wire material used, the thermal expansion coefficient of the photovoltaic element material, and the heating temperature, and is designed to have a desired length during thermal expansion.
In the case where the photovoltaic element has flexibility, when a metal wire shorter than the desired length is fixed to a part of the photovoltaic element, for example, as shown in FIG. In FIG. 4, 401 is a photovoltaic element, 402 is a metal wire, and 403 is an adhesive material. Since the metal wire shorter than the desired length is fixed, the photovoltaic element is deformed into a concave shape. By applying heat and pressure from this state, the metal wire is bonded in a state of being expanded by thermal expansion, so that a collector electrode having a desired length can be obtained.
[0015]
[Adhesive material]
About the adhesive material used in this invention, the function to fix the current collection electrode which consists of metal wires is required. Examples of the adhesive material include acrylic, rubber, silicone, polyvinyl ether, epoxy, polyurethane, nylon, polyamide, inorganic, and composite adhesives. Among these adhesives, acrylic adhesives and silicone adhesives are suitably used, particularly those having excellent adhesion, tack, holding power, electric resistance, moisture resistance and the like.
Furthermore, in order to improve workability and mass productivity, it is also possible to use a pressure-sensitive adhesive tape or a double-sided pressure-sensitive adhesive tape having a structure in which a base material and the above adhesive are stacked. As the base material at that time, heat resistance when the current collecting electrode is formed by heating is required. For example, polyimide, PET, or the like is used.
[0016]
【Example】
The following examples further illustrate the present invention in detail but are not to be construed to limit the scope thereof.
[0017]
[Example 1]
In this embodiment, the case where the photovoltaic element is an amorphous silicon photovoltaic element (solar cell) using a stainless steel substrate will be specifically described with reference to FIG.
As a substrate for a photovoltaic element, a rolled stainless steel substrate made of a stainless steel foil having a thickness of 0.15 mm with a cleaned surface was prepared. A photovoltaic element having a pin / pin structure was formed on the surface of the stainless steel substrate by the known plasma CVD method under the conditions shown in Table 1. A photovoltaic device 500 (239 cm × 356 cm) was produced by cutting a rolled stainless steel substrate on which a photovoltaic device having a pin / pin structure was formed. The following processing was sequentially performed on the photovoltaic element 500.
(1) An ITO etching material (FeCl _Three ) After the printed paste was screen-printed as in pattern 501 (FIG. 5A) and washed with pure water, a portion of the ITO layer was etched to ensure electrical separation between the upper and lower electrodes. .
(2) A double-sided tape 502 having a thickness of 200 μm (manufactured by Toyo Ink Co., Ltd., base material polyimide / PET composite, adhesive material silicon system) is shown immediately outside the etching region of the photovoltaic device 500 as shown in FIG. Affixed to
(3) Coated wire 503 (copper wire having a diameter of 100 μm, coated with carbon paste having a volume resistivity of 0.5 Ωcm with a thickness of 20 μm and dried), carbon paste is urethane resin (softening temperature Carbon black is dispersed at about 100 ° C. and diluted with IPA and ethyl acetate) is cut to a length of 354.7 cm and pasted on a double-sided tape 502 as shown in FIG. . At the time of pasting, the photovoltaic element 500 was first placed on a jig for fixing in a concave, and pasted while applying a little tension in order to stick the coated wire without sagging.
(4) As a bus bar for further collecting electricity from the coating wire 503, a silver-plated copper 504 (a copper foil having a thickness of 100 μm and a silver plating of about 1 μm on both sides) is fixed to the coating wire 503 Affixed on the double-sided tape 502 (FIG. 5D).
(5) Using the vacuum heating apparatus shown in FIG. 3, heating and pressing were performed, and the coating wire 503 was bonded onto the photovoltaic element 500. In this case, the temperature on the electrode formation surface was set to 200 ° C., and pressing was performed at a pressure of 1 kg / cm for 45 seconds.
Thereby, a solar cell was obtained. Ten solar cells were produced by the above method.
For the 10 solar cells obtained, the initial characteristics are 100 mW / cm in the AM1.5 global solar spectrum. ² When the conversion efficiency was measured using a pseudo solar light source (hereinafter referred to as a simulator) having a light quantity of 9.5% ± 0.03%, the characteristics were good and there was little variation. Series resistance is also 32 Ωcm on average ² It was a good value.
In any of the solar cells, the coated wire was adhered in a straight line, and no distortion was observed, and the appearance was good. Moreover, when the length of the coating wire was measured, it was about 355.0 cm, and it was found that the coating wire was bonded in an extended state from the initial length. Moreover, the desired length of 355.0 cm could be achieved.
[0018]
[Comparative Example 1]
This example is different from Example 1 in that a coated wire having a length of 355 cm is used instead of using a coated wire having a length of 354.7 cm.
The same procedure as in Example 1 was performed until the double-sided tape was applied, and then the same coating wire as used in Example 1 was cut to a length of 355.0 cm, as shown in FIG. 6 (a). Affixed on tape. At the time of pasting, unlike Example 1, the pasting was performed on a plane without making the photovoltaic element concave. However, in order to eliminate sagging, it was applied with some tension applied. Next, after attaching silver-plated copper as a bus bar in the same manner as in Example 1, 200 ° C., 1 kg / cm ² Then, pressing was performed for 45 seconds, and the coating wire was bonded onto the photovoltaic element. Thereby, a solar cell was obtained.
Ten solar cells were produced by the above method.
For the 10 solar cells obtained, the initial characteristics were measured using a simulator and the conversion efficiency was determined to be 9.5% ± 0.03%, which was as good as in Example 1. There was little variation. Series resistance is also 32 Ωcm on average ² It was a good value.
However, with respect to the appearance, most of the coated wires of the solar cell have been meandered and bonded as shown in FIG.
By comparing Example 1 with Comparative Example 1, it can be seen that the effect of the present invention is clear.
[0019]
[Table 1]

[0020]
【The invention's effect】
As described above, according to the present invention, it is possible to easily manufacture a photovoltaic device having no problem in characteristics and having a good appearance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a configuration of a collecting electrode provided with a coating layer of the present invention.
FIG. 2 is a cross-sectional view schematically showing a configuration of an amorphous silicon-based photovoltaic element of the present invention.
FIG. 3 is a cross-sectional view schematically showing a vacuum heating apparatus of the present invention.
FIG. 4 is a schematic view showing a situation where both ends of a coated wire are fixed to a photovoltaic element.
5 is a schematic view of a method for producing a photovoltaic element according to Example 1. FIG.
6 is a schematic view of a method for producing a photovoltaic element according to Comparative Example 1 and a schematic view showing a state of forming a collecting electrode. FIG.
[Explanation of symbols]
100, 402, 500, 503 Coating wire
101 metal wire
102 Barrier layer
103 Adhesive layer
201 substrate
202 Lower electrode
203, 213, 223 n-type semiconductor layer
204, 214, 224 i-type semiconductor layer
205, 215, 225 p-type semiconductor layer
206 Transparent conductive film
207 Current collecting electrode
301 Heating plate and lower chamber
302 heater
303,401 Photovoltaic element
304,308 Exhaust port
305 Resin sheet 1
306 Resin sheet 2
307 Upper chamber
403 Adhesive material
501 Etching line
502 Double-sided tape
504 Busbar

Claims (6)

In the method for manufacturing a photovoltaic element having a current collecting electrode made of a metal wire coated with a conductive resin layer, a step of fixing only both ends of the metal wire shorter than a desired length to a part of the photovoltaic element; And a step of adhering the metal wire on the surface of the photovoltaic device while thermally expanding the metal wire by heating and pressurizing. The method for manufacturing a photovoltaic element according to claim 1, wherein the photovoltaic element is flexible. The method for manufacturing a photovoltaic element according to claim 1, wherein the both ends are fixed using an adhesive material. The method for manufacturing a photovoltaic element according to claim 3, wherein the adhesive material is a double-sided tape. The method for manufacturing a photovoltaic element according to any one of claims 1 to 4, wherein heat for fixing the metal wire is within a range of 150 ° C or less from a softening temperature of the conductive resin layer. The method for manufacturing a photovoltaic element according to any one of claims 1 to 4, wherein a pressure for fixing the metal wire is 1 kg / cm ² or more and 10 kg / cm ² or less.

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