JP2011086671A - Solar cell, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell including unit cells having an organic thin film electromotive force layer, ends of adjacent unit cells being overlapped with each other to provide conduction, and capable of reducing resistance between a conductive base material of one unit cell and an upper electrode of the other unit cell in the overlapped portion, and to provide a method for manufacturing the solar cell. <P>SOLUTION: In a solar cell 1, a plurality of solar cell unit cells 2 are connected so that ends of adjacent unit cells are overlapped with each other. Each unit cell 2 includes: a conductive base material 3; an organic thin film electromotive force layer 4 laminated on the conductive base material 3; an upper electrode 5 laminated on the organic thin film electromotive force layer 4; and an auxiliary electrode 7 on the upper electrode. One end side of each unit cell 2 is overlapped on an auxiliary electrode collector 7a on the other side of the adjacent unit cell to be bonded by means of a conductive adhesive. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar cell in which a plurality of unit cells are connected in series, and in particular, a solar cell in which adjacent unit cells are connected in series so that the other end of an adjacent unit cell is superimposed on one end of a unit cell. It relates to batteries. Moreover, this invention relates to the manufacturing method of this solar cell.

  As a connection method of unit cells of solar cells formed by connecting a plurality of solar cell unit cells (hereinafter sometimes simply referred to as unit cells) in series, the other end of the unit cell adjacent to one end of the unit cell is used. Patent Documents 1 and 2 describe superposing and electrically connecting the upper electrode of one unit cell and the lower electrode (conductive substrate) of the other unit cell.

  Patent Document 1 describes that an auxiliary electrode made of aluminum is provided on an upper electrode made of ITO (upper right column on page 3).

  In Patent Documents 1 and 2, the photovoltaic layer is a silicon layer, but in recent years, development of an organic thin-film solar cell in which the photovoltaic layer is formed of an organic thin film has been promoted (for example, Patent Document 3). ).

JP 62-36879 A JP-A-11-186577 JP2009-99805

  In the solar cell in which the end portions of the unit cells are overlapped as described above, it is desirable that the resistance between the conductive base material of one unit cell and the upper electrode of the other unit cell is small.

  The present invention relates to a solar cell in which end portions of unit cells having an organic thin film are superposed and conducted, and a conductive base material of one unit cell and an upper electrode of the other unit cell in the overlapped portion. It aims at providing the solar cell which can make resistance between, and its manufacturing method small.

  The solar cell according to claim 1 is a solar cell in which a plurality of unit cells in which an electromotive force layer and a light transmissive upper electrode are stacked on a conductive base material are connected in series, and adjacent unit cells. In the solar cell in which the other ends of the upper electrode at one end of the conductive substrate of one unit cell are connected by overlapping the end portions of the unit cell, the electromotive force layer is an organic thin film electromotive force layer An auxiliary electrode is provided on the upper electrode, and one end of the auxiliary electrode is interposed in an overlapping portion of the unit cells.

  The solar cell of claim 2 is characterized in that, in claim 1, the auxiliary electrode is provided with a current collector, and the current collector is provided only in a region where unit cells overlap each other. is there.

  According to a third aspect of the present invention, there is provided a solar cell according to the second aspect, wherein the current collector has an opening, and a conductive adhesive is attached to the opening, and the ends of the unit cells are connected to each other by the conductive adhesive. It is characterized by being bonded.

  The method for producing a solar cell according to claim 4 is a method for producing the solar cell according to claim 2 or 3, wherein an organic thin film electromotive force layer and an upper electrode are formed on the raw material of each conductive substrate. Forming a unit cell original having a plurality of unit cell parts by providing a plurality of auxiliary electrodes on the upper electrode, and one unit cell from one end of the unit cell original A step of separating, a step of joining the separated unit cells on the auxiliary electrode on one end side of the remaining unit cell original fabric, and a unit cell connection by separating the unit cell portion on one end side from the unit cell original fabric A step of separating the body and the remaining unit cell raw material, a step of overlapping and joining the unit cell connecting body on the auxiliary electrode on one end side of the remaining unit cell raw material, and one end side from the unit cell raw material Separate the unit cell part of the unit cell unit and the remaining unit cell. And separating the raw city, it is characterized in that it has a.

  In the solar cell of the present invention, the auxiliary electrode is provided on the upper electrode of the unit cell, and one end of the auxiliary electrode is interposed in the overlapping portion of the unit cells. The resistance between the conductive substrate and the upper electrode of the other unit cell is small.

  In particular, a resistance between the conductive substrate of one unit cell and the current collector is provided by providing a current collector on one end of the upper electrode and interposing the current collector in an overlapping portion of the unit cells. Is small.

  An opening may be provided in the current collector, and the unit cells may be joined through the opening. In this way, it is possible to prevent the problem that the conductive adhesive protrudes at the time of joining and the upper electrode and the lower electrode become conductive.

  When manufacturing the solar cell of the present invention, the individual unit cells may be connected with the end portions being overlapped as described above, and the unit cell is a unit cell portion of the original unit cell. Unit cells may be connected, and the connected unit cell portions may be separated from other portions of the unit cell original. In the latter case, it is possible to easily align the long laminated body by applying tension from both ends without using a work procedure that is difficult to automate, such as handling a flexible unit cell. The effect that work becomes possible is acquired.

It is sectional drawing of the solar cell which concerns on embodiment. It is a typical perspective view which shows the lamination | stacking system of the solar cell which concerns on embodiment. It is a top view of the unit cell which concerns on another embodiment. It is explanatory drawing of the manufacturing method of a solar cell. It is explanatory drawing of the manufacturing method of a solar cell.

  The first embodiment will be described with reference to FIG. 1 and FIG. FIG. 1 is a cross-sectional view in the unit cell thickness direction of a solar battery according to an embodiment, and FIG. 2 is a perspective view schematically showing the overlapping state of unit cells.

  As shown in FIGS. 1 and 2, the solar cell 1 is formed by connecting a plurality of unit cells 2 so that the ends of the unit cells 2 overlap each other. The unit cell 2 includes a conductive base material 3, an organic thin film electromotive force layer 4 laminated on the conductive base material 3, an upper electrode 5 laminated on the organic thin film electromotive force layer 4, and the upper part. And an auxiliary electrode 7 provided on the electrode 5.

  As shown in FIG. 1, the other end (right end side) of the other adjacent unit cell 2 is superimposed on one end (left end side in FIGS. 1 and 2) of one unit cell 2, and The conductive substrate 3 and the upper electrode 5 of the adjacent unit cell 2 are connected and are electrically connected. The end portions of the unit cell 2 are preferably connected by a conductive adhesive.

  The auxiliary electrode 7 includes a current collecting portion 7a along one end of the unit cell 2, and a comb-like portion 7b extending orthogonally from the current collecting portion 7a. The current collector 7 a is interposed in the overlapping portion of the unit cells 2. The current collector 7a is provided only in the overlapping portion.

  In this solar cell 1, the auxiliary electrode 7 is provided on the upper electrode 5, and the current collector 7 a of the auxiliary electrode 7 is interposed in the overlapping portion of the unit cells 2, 2, so that one unit The resistance between the upper electrode of the cell 2 and the conductive substrate 3 of the other unit cell 2 is small. In particular, in this embodiment, the current collector 7a extending along the overlap portion is provided, and the current collector 7a is interposed in the overlap portion between the unit cells 2, so that the auxiliary electrode 7 and the conductive group The contact area with the material 3 is large, and the resistance between them is small.

  From such a thing, the solar cell 1 of this invention has small connection resistance between unit cells, and can take out electric power efficiently.

  Although three unit cells 2 are shown in FIG. 1, two or four or more unit cells 2 may be connected in series. Usually, 10 to 200, especially 20 to 100 unit cells are connected in series. The output terminals are drawn out from the upper electrode 5 of the leftmost unit cell and the conductive base material 3 of the rightmost unit cell in FIG.

  The connection body of the unit cell 2 is disposed on a substrate made of a synthetic resin sheet, a glass plate or the like, and a sealing material made of a light-transmitting synthetic resin or the like is provided so as to cover the substrate, thereby forming a solar cell product. .

[Another shape of auxiliary electrode]
In the present invention, like the auxiliary electrode 7A shown in FIG. 3, the frame-shaped current collector 7c is provided, and the unit cells 2 are joined together by attaching a conductive adhesive to the opening 8 inside the frame-shaped portion. May be. In this way, it is possible to prevent the problem that the conductive adhesive protrudes at the time of joining and the upper electrode and the lower electrode become conductive. In this embodiment, the frame-shaped current collecting portion 7c has a “day” shape having a crossing portion 7d in the middle thereof, but the crossing portion 7d may be omitted. Further, two or more crossing portions may be provided. For example, by providing two crossing portions, an “eye” -shaped current collecting portion may be provided.

[Method for manufacturing solar cell]
An example of the method for producing the solar cell of the present invention is shown in FIG.

  First, an organic thin-film electromotive force layer and an upper electrode are formed on a raw material of a conductive substrate unwound from a raw material roll or the like as shown in FIG. Is deposited. Thereby, the unit cell original fabric 10 in which the plurality of unit cell portions 2A are formed on one original fabric is obtained. Therefore, as shown in FIG. 5B, the unit cell 2 is manufactured by cutting the unit cell original fabric 10 for each unit cell portion 2A. A solar cell 1 is obtained by connecting the obtained unit cells 2 with their end portions overlapped as shown in FIGS.

  In FIG. 4, the unit cell raw fabric 10 is divided into individual unit cells 2 and then the unit cells 2 are sequentially connected. However, as shown in FIG. The cell 2 may be cut out and connected to the unit cell portion 2A on one end side of the remaining unit cell original fabric 10, and a solar cell may be manufactured by repeating this process.

  That is, as shown in FIG. 5A, one unit cell 2 is separated from the left end side of the unit cell original fabric 10 having a plurality of unit cell portions 2A. The right end side of the unit cell 2 is overlaid on the current collecting portion 7a of the unit cell portion 2A on the left end side of the remaining unit cell original fabric 10 as shown in FIG. 5 (b), and is joined with a conductive adhesive. . Next, as shown in FIG. 5C, the unit cell portion 2A on the left end side is separated from the unit cell original fabric 10.

  As a result, a connecting body in which two unit cells 2 are connected and a remaining unit cell original fabric are obtained, so that the right end side of this connecting body is a collection of unit cell portions 2A on the left end side of the remaining unit cell original fabric 10. The unit cell part 2 </ b> A on the left end side of the unit cell original fabric 10 is separated from the unit cell original fabric 10. As a result, as shown in FIG. 5 (d), a connecting body in which the three unit cells 2 are connected and the remaining unit cell original fabric.

  Thereafter, by repeating the same procedure, a solar cell to which a required number of unit cells 2 are connected is obtained.

  According to the method of FIG. 5, it is possible to easily position a long laminate by applying tension from both ends without using a work procedure that is difficult to automate such as handling a flexible unit cell. The effect that it becomes possible to work together is obtained.

  In the above description, the unit cells 2 are bonded to each other with a conductive adhesive, but may be bonded by ultrasonic welding or the like.

  Although illustration is omitted, an electrode made of a film similar to that of the current collector may be provided between the auxiliary electrode current collector 7a and the edge of the upper electrode 5 along the edge.

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

[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 holes or electrons contribute to electrical conduction, and depend 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 some of the same substances exhibit 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 of 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.

[Conductive substrate and upper electrode]
The conductive substrate and the upper electrode can be formed of a conductive material, such as platinum, gold, silver, aluminum, chromium, nickel, copper, titanium, magnesium, calcium, barium, sodium, etc. Metals or their alloys; metal oxides such as indium oxide and tin oxide or their alloys (ITO); conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene; hydrochloric acid, sulfuric acid, sulfone Acids such as acids, Lewis acids such as FeCl ₃ , halogen atoms such as iodine, metal atoms such as sodium and potassium, and the like; conductive particles such as metal particles, carbon black, fullerene, and carbon nanotubes Conductive composite material dispersed in matrix such as polymer binder Is mentioned. 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.

  At least the upper electrode on the light receiving surface side is preferably light transmissive for power generation. However, even if the electrode is not transparent, it does not necessarily have to be transparent if the power generation performance is not significantly adversely affected. Examples of transparent electrode materials include oxides such as ITO and indium zinc oxide (IZO); and metal thin films. At this time, the specific range of the light transmittance is not limited, but considering the power generation efficiency of the solar cell element, 80% or more is preferable except for the loss due to partial reflection at the optical interface.

  In addition, the material of a conductive base material and an upper electrode may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  In addition, there is no restriction | limiting in the formation method of an upper electrode. For example, it can be formed by a dry process such as vacuum deposition or sputtering. For example, it can also be formed by 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.

  Furthermore, two or more electrodes may be laminated, and characteristics (electric characteristics, wetting characteristics, etc.) due to surface treatment may be improved.

[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 Solar cell 2 Unit cell 2A Unit cell part 3 Conductive base material 4 Organic thin-film electromotive force layer 5 Upper electrode 7 Auxiliary electrode 7a, 7c Current collection part 7b Comb part 8 Opening part 10 Unit cell original fabric

Claims (4)

A solar cell in which a plurality of unit cells in which an electromotive force layer and a light transmissive upper electrode are stacked on a conductive base material are connected in series,
In the solar cell in which one end of the conductive substrate of one unit cell and the other end of the upper electrode are connected by overlapping the ends of adjacent unit cells,
The electromotive force layer is an organic thin film electromotive force layer, an auxiliary electrode is provided on the upper electrode, and one end of the auxiliary electrode is interposed in an overlapping portion of the unit cells. battery.   The solar cell according to claim 1, wherein the auxiliary electrode includes a current collector, and the current collector is provided only in a region where the unit cells overlap each other.   3. The current collector according to claim 2, wherein the current collector has an opening, a conductive adhesive is attached to the opening, and the ends of the unit cells are bonded to each other by the conductive adhesive. Solar cell. 4. The method of manufacturing a solar cell according to claim 2, wherein an organic thin film electromotive force layer and an upper electrode are formed on the raw material of each conductive base material, and a plurality of the organic thin film electromotive force layers are formed on the upper electrode. A step of producing a unit cell raw material having a plurality of unit cell parts by providing the auxiliary electrode,
Separating one unit cell from one end of the unit cell original fabric,
A step of overlapping and joining the separated unit cell on the auxiliary electrode on one end side of the remaining unit cell original fabric,
Separating the unit cell portion on one end side from the unit cell original fabric and separating it into a unit cell connector and the remaining unit cell original fabric;
A step of overlapping and joining the unit cell connection body on the auxiliary electrode on one end side of the remaining unit cell original fabric,
Separating the unit cell portion on one end side from the unit cell original fabric and separating it into a unit cell connector and the remaining unit cell original fabric;
A method for producing a solar cell, comprising:

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