JP2011096914A - Solar cell and method of manufacturing the same - Google Patents

Abstract

An organic thin film electromotive force layer and an electrode are formed on a sheet-like conductive substrate, and then the sheet-like conductive substrate is cut to prevent short-circuiting of electrodes in a solar cell.
An organic thin film electromotive force layer 2 and an upper electrode 3 are formed on a sheet-like conductive substrate 1 by a coating method, and an auxiliary electrode 4 is formed on the upper electrode 3. The organic thin film electromotive force layer 2 is formed on the entire surface of the sheet-like conductive substrate 1. The upper electrode 3 is applied so that there is a space between them. In this space portion, the solar cell sheet 7 is cut in the sheet width direction to form individual solar cells.
[Selection] Figure 2

Description

  The present invention relates to a solar cell in which at least an organic thin film electromotive force layer and an upper electrode are formed on a flexible conductive substrate, and a method for manufacturing the solar cell.

  Conventionally, solar cells have been manufactured using a flexible material that is not easily broken, such as a glass substrate and a silicon wafer. On the other hand, Japanese Patent Application Laid-Open No. 11-243224 proposes that a solar battery cell is produced on a flexible base material such as polyester, polyethylene, or polycarbonate. Such a flexible substrate has the advantage that it is difficult to break, the module structure of the solar cell can be reduced in weight, and can be installed at a lower construction cost. In addition, when a conductive substrate is used as the flexible substrate, a desired output voltage can be obtained by connecting cells in series so that the cells are overlapped as disclosed in JP-A-11-186777. It becomes possible. According to this method, as compared with a method in which electrodes and a photoelectric conversion layer are patterned with a laser and serialized on a substrate as in JP-A-5-183177, the manufacturing cost is reduced.

  Japanese Patent Application Laid-Open No. 2008-201819 describes that a photoelectric conversion layer of a solar battery cell is formed by an organic semiconductor material coating method. By forming a photoelectric conversion layer on a flexible substrate by such a coating method, a lightweight solar cell module can be manufactured at low cost. Note that the organic semiconductor material has flexibility and can have a very thin film thickness (several tens to 100 nm), and is suitable for film formation on a flexible substrate.

JP-A-11-243224 JP-A-11-186577 JP 5-183177 JP2008-201819

  In order to produce a solar cell module at a low cost, a method for producing a solar cell by cutting a photoelectric conversion layer and an electrode layer on a conductive substrate having a large area as much as possible is preferable. When the laminated film is cut, there is a problem that the upper electrode and the conductive base material that is the lower electrode are short-circuited. In order to prevent this, for example, as disclosed in JP-A-11-143224, a part of the upper electrode is removed by etching or laser and then cut.

  However, the method of removing the upper electrode by a process such as etching has a problem that the manufacturing cost is high. In addition, since the upper electrode is conventionally formed by a vacuum process such as sputtering, the manufacturing cost is high.

  The organic semiconductor material has characteristics that it can be formed by coating and has excellent flexibility. Such a material is the most suitable manufacturing process to form a film on a flexible substrate by a continuous coating process. In order to reduce the manufacturing cost, the material is continuously rolled out while being rolled out. A method of forming a film is taken. Since the speed of such a continuous coating process is generally faster than the speed of a sputtering process using a vacuum apparatus or a patterning process using a laser, it is difficult to design an efficient production line.

  The present invention reduces the manufacturing cost of a solar cell obtained by forming an organic thin film electromotive force layer and an electrode on a sheet-like conductive substrate and then cutting the sheet-like conductive substrate, and cutting the sheet. It aims at preventing the short circuit of the electrode by.

  The solar cell of the present invention (Claim 1) is a solar cell in which at least an organic thin-film electromotive force layer and a light-transmitting upper electrode are laminated on a flexible conductive substrate, and at least the upper portion In the solar cell in which the electrode is formed by a coating method, the edge of the upper electrode is set back from the edge of the conductive substrate toward the center of the solar cell.

  The solar cell of claim 2 is characterized in that, in claim 1, the edge of the upper electrode is set back from the edge of the conductive base material by 0.1 to 10 mm toward the center of the solar cell. Is.

  A solar cell according to a third aspect is characterized in that, in the first or second aspect, an edge of the organic thin film electromotive force layer and an edge of the conductive base material coincide with each other.

  The manufacturing method of the photovoltaic cell of Claim 4 is a method of manufacturing the solar cell of any one of Claim 1 thru | or 3, Comprising: A several unit solar cell is provided on a sheet-like electroconductive base material. A solar cell sheet manufacturing process for manufacturing the solar cell sheet, and a cutting process for cutting the solar cell sheet and separating it into each solar cell. In the solar cell sheet manufacturing process, each unit The upper electrode of the solar cell is provided by a coating method so as to leave a space between each other, and in the cutting step, the solar cell sheet is cut at a space portion between the upper electrodes. is there.

  The method for manufacturing a solar battery cell according to claim 5 is characterized in that, when the upper electrode is formed by a coating method, the upper electrode is applied so that the space is provided between the upper electrodes. To do.

  The solar cell of the present invention is obtained by forming at least an organic thin film electromotive force layer and a light transmissive upper electrode on a base sheet, and then cutting each solar cell. By forming the light-transmitting upper electrode by applying a conductive polymer or the like, the manufacturing cost of the solar cell can be reduced. At the time of film formation by this application, application is performed to a region excluding the peripheral portion of the line to be cut in advance, and in the cutting step, cutting is performed along the line, thereby preventing a short circuit between the upper electrode and the lower electrode. According to this method, the step of removing the upper electrode before cutting can be omitted, and the manufacturing cost can be reduced.

  In the method of the present invention, the upper electrode is formed into a pattern by coating, and patterning with a laser is not performed. Therefore, an efficient production line can be designed.

  Moreover, even if the solar cell module of the present invention is bent, cracks and the like do not occur and the performance does not deteriorate. As a result, various usage forms such as rolling and storing are possible.

It is a typical top view which shows the manufacturing method of the solar cell which concerns on embodiment. It is a longitudinal cross-sectional view (cross-sectional view in the sheet thickness direction) of the II part of FIG. It is a longitudinal cross-sectional view of the III part of FIG.

  Next, an example of a method for producing the solar cell of the present invention will be described.

  First, as shown in FIGS. 1 (a) and 2, an organic thin film electromotive force layer 2 and an upper electrode 3 are formed by a coating method on a sheet-like conductive substrate 1 unwound from a raw roll or the like. The auxiliary electrode 4 is formed on the upper electrode 3 by a coating method. The organic thin film electromotive force layer 2 is formed on the entire surface of the sheet-like conductive substrate 1. The upper electrode 3 is applied in a pattern having a space (space) in the longitudinal direction of the sheet-like conductive substrate 1. The auxiliary electrode 4 is formed on each upper electrode 3. The auxiliary electrode 4 includes a current collecting portion 4a extending in the width direction of the sheet-like conductive base material 1 along one end side of the upper electrode 3, and a comb-like portion 4b extending orthogonally from the current collecting portion 4a. And.

  Thereby, the solar cell sheet 7 in which the unit solar cell portions 5 partitioned by the space between the upper electrodes 3 are arranged in the sheet longitudinal direction is obtained. In FIG. 1 (a), only four unit solar cell parts 5 are shown, but the sheet-like conductive base material 1 extends long in the left-right direction of FIG. A unit solar cell portion 5 is formed.

  Next, as shown in FIGS. 1B and 3, the solar cell sheet 7 is cut in the sheet width direction in the space portion between the upper electrodes 3. C in FIG. 2 shows this cutting position. The cutting position C is preferably in the middle between the upper electrodes 3 and 3. Examples of the cutting means include a cutter blade and laser cutting.

  In this way, each unit solar cell unit 5 is cut and separated to obtain a solar cell 5A. In this solar cell 5A, the upper electrode 2 is separated from the edge (cut end surface) of the solar cell 5A by a predetermined distance L, so that the upper electrode 3 and the conductive substrate 1 are prevented from being short-circuited. Is done. This L is preferably about 0.1 to 10 mm, particularly about 0.5 to 5 mm. Since the organic thin film electromotive force layer 2 is cut together with the sheet-like conductive base material 1, the edge of the organic thin film electromotive force layer 2 matches the edge of the cut conductive base material 1.

  Further, in this solar cell 5A, the organic semiconductor layer 2, the upper electrode 3 and the like are formed by a coating method, and the upper electrode 3 is formed by pattern coating so that the space is opened, Manufacturing cost is low. In other words, it is possible to reduce the manufacturing cost of the solar cell by forming the upper electrode by applying conductive ink. Further, since the coating is performed on the area excluding the peripheral portion of the line to be cut in advance during the film formation by coating, it is possible to omit the step of removing the upper electrode before cutting, thereby further reducing the manufacturing cost. Can do. In addition, since the upper electrode is also formed by coating, patterning by laser is not used, and pattern coating is performed at the time of film formation, so that an efficient production line can be designed.

  The solar cell 5A thus manufactured is arranged so as to be connected in series on a substrate made of a synthetic resin sheet, a glass plate or the like, and sealed with a translucent synthetic resin or the like so as to cover it. Materials are provided to make solar cell products. In addition, it is preferable to connect the solar cells 5A in series so that the conductive base material 1 of one adjacent solar cell 5A is stacked on the current collecting part 4a of the other solar cell 5A.

  Next, preferred examples and thicknesses of materials constituting each part of the solar cell will be described.

[Conductive substrate]
The material of the conductive substrate is preferably iron, copper, aluminum, zinc, tin, chrome, nickel or an alloy thereof, and particularly preferably an aluminum alloy or stainless steel. The thickness is preferably 10 μm to 300 μm. As the surface roughness, an arithmetic average surface roughness (Ra) of about 0.8 μm to 3.2 μm is usually preferable. The linear thermal expansion coefficient is usually preferably about 5 to 40 ppm / ° C. The conductive substrate may be one in which a conductive film is entirely formed on the surface of the synthetic resin film. Examples of the material for the conductive film include materials for the upper electrode described later.

[Organic thin film electromotive force layer]
The organic thin film electromotive force layer is formed of an organic semiconductor. Organic semiconductors are classified into p-type and n-type depending on semiconductor characteristics. The p-type and n-type indicate whether it is a hole or an electron that contributes to electrical conduction, and depends on the electronic state, doping state, and trap state of the material. Therefore, there are cases where p-type and n-type cannot always be clearly classified, and there are cases where the same substance exhibits both p-type and n-type characteristics.

  Examples of p-type semiconductors include porphyrin compounds such as tetrabenzoporphyrin, tetrabenzocopper porphyrin, tetrabenzozinc porphyrin; phthalocyanine compounds such as phthalocyanine, copper phthalocyanine, zinc phthalocyanine; naphthalocyanine compounds; polyacenes of tetracene and pentacene; Examples thereof include oligothiophene and derivatives containing these compounds as a skeleton. Furthermore, polymers such as polythiophene, polyfluorene, polyphenylene vinylene, polytriallylamine, polyacetylene, polyaniline, polypyrrole and the like including poly (3-alkylthiophene) are exemplified.

  Examples of n-type semiconductors include fullerenes (C60, C70, C76); octaazaporphyrins; perfluoro compounds of the above p-type semiconductors; naphthalenetetracarboxylic acid anhydrides, naphthalenetetracarboxylic acid diimides, perylenetetracarboxylic acid anhydrides, perylenes And aromatic carboxylic acid anhydrides such as tetracarboxylic acid diimide and imidized products thereof; and derivatives containing these compounds as a skeleton.

  The specific configuration of the organic semiconductor layer is arbitrary as long as at least a p-type semiconductor and an n-type semiconductor are contained. It may be constituted only by a single layer film or may be constituted by two or more laminated films. For example, an n-type semiconductor and a p-type semiconductor may be contained in separate films, or an n-type semiconductor and a p-type semiconductor may be contained in the same film. In addition, each of the n-type semiconductor and the p-type semiconductor may be used alone or in combination of two or more in any combination and ratio.

  Specific examples of the structure of the organic semiconductor layer include a bulk heterojunction type having a layer (i layer) in which a p-type semiconductor and an n-type semiconductor are phase-separated in the layer, a layer containing a p-type semiconductor (p layer), and n, respectively. Examples include a stacked type (hetero pn junction type) in which a layer containing a p-type semiconductor (p layer) has an interface, a Schottky type, and a combination thereof. Among these, a bulk heterojunction type and a combination of a bulk heterojunction type and a stacked type (p-i-n junction type) are preferable because they exhibit high performance.

  Although there is no restriction | limiting in the thickness of p layer of an organic-semiconductor layer, i layer, and n layer, Usually, it is preferable to set it as 3 nm or more, especially 10 nm or more, and usually 200 nm or less, especially 100 nm or less. Increasing the layer thickness tends to increase the uniformity of the film, and decreasing the thickness tends to improve the transmittance and decrease the series resistance.

  A method for forming the organic semiconductor layer is not particularly limited, but a wet process in which an ink containing the semiconductor material is applied is preferable.

[Upper electrode]
The upper electrode can be formed of a conductive material, for example, a metal such as platinum, gold, silver, aluminum, chromium, nickel, copper, titanium, magnesium, calcium, barium, sodium, or an alloy thereof. Metal oxides such as indium oxide and tin oxide, or alloys thereof (ITO); conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyacetylene; acids such as hydrochloric acid, sulfuric acid, and sulfonic acid; A material containing a dopant such as a Lewis acid such as FeCl ₃ , a halogen atom such as iodine, or a metal atom such as sodium or potassium; a matrix such as a metal binder, conductive particles such as carbon black, fullerene, or carbon nanotube. And conductive composite materials dispersed in the material. Especially, the material which has deep work functions, such as Au and ITO, is preferable for the electroconductive base material or electrode which collects a hole. On the other hand, a material having a shallow work function such as Al is preferable for the conductive base material or electrode for collecting electrons. By optimizing the work function, there is an advantage of favorably collecting holes and electrons generated by light absorption.

  The upper electrode on the light receiving surface side is light transmissive for power generation. Examples of the transparent electrode material include oxides such as ITO and indium zinc oxide (IZO). Although there is no restriction | limiting in the specific range of the light transmittance of an upper electrode, when the electric power generation efficiency of a solar cell element is considered, 80% or more is preferable except the loss by the partial reflection in an optical interface.

  In addition, the material of the upper electrode may be used alone or in combination of two or more in any combination and ratio.

  The upper electrode is formed by a coating method, specifically, a wet process using conductive ink or the like. At this time, any conductive ink can be used. For example, a conductive polymer, a metal particle dispersion, or the like can be used.

  Two or more electrodes may be laminated, and characteristics (electric characteristics, wetting characteristics, etc.) may be improved by surface treatment.

[Other layers]
The solar cell of the present invention may include layers other than the above, such as a buffer layer. The buffer layer is a layer provided at the electrode interface facing the organic semiconductor layer for improving electrical characteristics and the like. For example, poly (ethylenedioxythiophene): poly (styrenesulfonic acid) (PEDOT: PSS), molybdenum oxide, lithium fluoride, 2,9dimethyl-4,7-diphenyl-1,10-phenanthroline, and the like can be given.

DESCRIPTION OF SYMBOLS 1 Conductive base material 2 Organic thin film electromotive force layer 3 Upper electrode 4 Auxiliary electrode 4a Current collection part 4b Comb-like part 5 Unit solar cell part 5A Solar cell 7 Solar cell sheet

Claims (5)

In a solar cell in which at least an organic thin film electromotive force layer and a light-transmitting upper electrode are laminated on a flexible conductive substrate, and at least the upper electrode is formed by a coating method. ,
The solar cell, wherein an edge of the upper electrode recedes toward a center side of the solar cell from an edge of the conductive substrate.   2. The solar cell according to claim 1, wherein the edge of the upper electrode recedes 0.1 to 10 mm toward the center of the solar cell with respect to the edge of the conductive substrate.   3. The solar cell according to claim 1, wherein an edge of the organic thin film electromotive force layer and an edge of the conductive substrate are matched. It is a method of manufacturing the solar cell of any one of Claim 1 thru | or 3, Comprising: The solar cell sheet manufacture which manufactures the solar cell sheet which has the several unit solar cell on the sheet-like electroconductive base material. Process,
Cutting the solar cell sheet and cutting each solar cell,
In the solar cell sheet manufacturing process, the upper electrode of each unit solar cell is provided by a coating method so as to leave a space between each other,
In the cutting step, the solar cell sheet is cut at a space portion between the upper electrodes.   5. The method for manufacturing a solar cell according to claim 4, wherein when the upper electrode is formed by a coating method, the upper electrode is applied so that the space is provided between the upper electrodes.

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