JPH0519992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to an integrated amorphous solar cell provided on an insulating substrate, in which a plurality of unit cells are electrically connected, and a method for manufacturing the same. More specifically, it is formed by sequentially electrically connecting the first electrodes and second electrodes of adjacent unit cells of a plurality of unit cells formed on an insulating substrate, each consisting of a first electrode layer, an amorphous semiconductor layer, and a second electrode layer. The present invention relates to an integrated solar cell that has a small connection area and a large active area, and a manufacturing method for manufacturing the amorphous solar cell by a dry process using laser light. [Prior art] Amorphous silicon semiconductor films can be deposited uniformly over a wide area at low substrate temperatures by glow discharge decomposition using silane gas, etc., and can be applied to various substrates such as glass, polymer films, ceramic plates, and metal foils. Since it can be selected, it has been widely studied as a semiconductor film for solar cells. As a basic structure of an amorphous silicon solar cell, a laminated structure of a metal electrode layer/amorphous silicon semiconductor layer/transparent electrode layer provided on the above-mentioned various substrates is known. Taking advantage of the characteristics of amorphous silicon layer deposition, it is easy to install solar cells with the above basic structure over a large area, but as it is, the maximum output voltage is around 0.6 to 5 V regardless of the area, making it difficult for power applications. 100V required
It is not possible to obtain a higher output voltage. The integration method to obtain such a practical voltage is as follows.
A method in which solar battery unit cells of a predetermined small area are provided on a small area substrate and then a predetermined number of these unit cells are connected in series. A method in which unit cells of a predetermined small area are deposited on a large-area substrate in the divided state using a mask, etc., and then a predetermined number of unit cells are connected in series. method is known. Among these methods, these methods are not suitable for mass production methods that take advantage of the characteristics of amorphous silicon layer deposition;
Moreover, the process of connecting in series and the process of modularizing becomes complicated. Although this method is possible by combining resist coating and etching, it requires many steps such as resist coating, exposure, cleaning and etching, and is not suitable for manufacturing solar cells in large quantities at low cost. In this method, the solar cell constituent layers are generally deposited one after another by placing a metal mask in close contact with the substrate. However, in the case of large-area substrates, the substrate may have different thermal expansion coefficients during the deposition of each layer. Adhesion between the substrate and the mask deteriorates, often causing the deposited components to wrap around in each layer, making it impossible to obtain a good divided pattern. Furthermore, in the case of division by the mask deposition method, it is difficult to align the mask, and it is difficult to reduce the error to about 0.5 mm or less. In addition, the integrated amorphous solar cell obtained by the above-mentioned conventional method has the problem that the area of the connecting part for connecting the unit cells becomes large, which reduces the overall active area and reduces the area efficiency of the solar cell as a whole. Ta. [Objective of the Invention] The present invention has been made to solve the above-mentioned drawbacks, and provides a large-area integrated amorphous solar cell in which a plurality of unit cells are connected in series on a large-area insulating substrate with good area efficiency. It is an object of the present invention to provide a manufacturing method for integrating and manufacturing a battery and the solar cell by a dry process using laser light with good productivity. [Structure and operation of the invention] The above objects are achieved by the present invention as described below.
That is, the present invention provides a plurality of divided unit cells each consisting of a first electrode layer, an amorphous semiconductor layer, and a second electrode layer that are stacked on an insulating substrate.
The first electrode layer and the second electrode layer of unit cells adjacent to each other
In an amorphous solar cell in which electrode layers are sequentially electrically connected, a second electrode is formed along a cell dividing groove formed by a laser beam irradiation method to divide the cell into unit cells and a cell dividing groove between adjacent unit cells by a laser beam irradiation method. An electrode dividing groove that divides the layer to form a connection part of a predetermined width between the cell dividing groove, a closing resin layer made of electrically insulating resin that closes the cell dividing groove and the electrode dividing groove, and a cell dividing groove. A connecting electrode layer that electrically connects the second electrode layer of one of the adjacent unit cells and the connecting part of the other unit cell, which is provided across the connecting part, and a connecting electrode layer formed by laser welding on the connecting part and the first connecting electrode layer. A first invention is an amorphous solar cell characterized by comprising a welding part for electrically connecting an electrode layer and electrically connecting unit cells, and a method for manufacturing an amorphous solar cell according to the first invention, The second invention is the following manufacturing method in which a large-area solar cell is divided into unit cells, electrically connected, and integrated by laser scribing and laser welding. That is, in the second invention, a plurality of divided unit cells each consisting of a first electrode layer, an amorphous silicon layer, and a second electrode layer provided in a stacked manner on an insulating substrate are connected to one of the adjacent unit cells. In the method for manufacturing an amorphous solar cell in which the first electrode layer of one unit cell and the second electrode layer of the other unit cell are sequentially electrically connected, the first electrode layer, the amorphous silicon layer, and the second electrode layer are formed on the insulating substrate. After forming a continuous cell in which two electrode layers are sequentially laminated, (a) scanning the cell division pattern to be divided into unit cells with a first laser beam to form a unit cell dividing groove for cutting all layers of the continuous cell; , the process of dividing into unit cells. (b) A second laser beam scans an electrode division pattern that forms a connection part along the cell division pattern between unit cells to be connected, and creates an electrode division groove for cutting the second electrode layer to form each unit cell. (c) forming a closing resin layer made of electrically insulating resin to close the cell dividing groove and the electrode dividing groove; (d) straddling the cell dividing groove between adjacent unit cells; (e) forming a connection electrode layer that connects the second electrode layer of one unit cell and the second electrode layer of the connection part of the other unit cell; (e) irradiating the connection part with a third laser beam to form the connection part; A continuous cell is divided into a plurality of units by the steps of laser welding and electrically connecting the first electrode layer and the connecting electrode layer, and then the unit cells are electrically connected and integrated. This is a method for manufacturing an amorphous solar cell. As is clear from the above configuration, the first aspect of the present invention
According to the invention, since the unit cells are connected by laser welding at the connecting portion separated by the cell dividing groove and the electrode dividing groove, sufficient electrical connection can be made in a very small area of the connecting portion, and the active area is large. In other words, an integrated amorphous solar cell with good area efficiency can be obtained. In particular, in the case where a collector electrode is provided, by using the bus bar portion as the connection portion, there is almost no reduction in the active area due to the connection. In addition,
In the above-described invention, it is important to form the connecting portions along the cell dividing grooves between the unit cells to be connected. As described above, the first aspect of the present invention has good area efficiency, and the cell division grooves or electrode division grooves are formed by a laser irradiation method, unlike the conventional mask method, and therefore has the following advantages. In other words, as mentioned above, in the conventional method, each time the various constituent layers of the first electrode, the amorphous semiconductor layer, and the second electrode layer are deposited, it is necessary to perform a process of dividing each layer, which reduces the damage caused when handling each layer. In most cases, when the dividing grooves are formed by a laser beam irradiation method, the various constituent layers can be uniformly deposited and then divided into parts, so there is less damage during handling due to patterning, and the yield is greatly improved. In addition, when dividing the amorphous silicon layer into a predetermined pattern using the laser irradiation method described above, a patterned resin layer made of electrically insulating resin is formed by screen printing or the like in advance on the laser beam irradiation portion, so that the amorphous silicon layer is crystallized. It is possible to avoid an increase in leakage current due to heat dissipation and the occurrence of short circuit points due to scattering of electrode layer components, maintain good battery performance, and easily apply it to long, large-area solar cells, thereby improving productivity. In addition, when connecting the unit cells electrically, forming connection electrodes by screen printing greatly improves productivity and allows the connection electrode layer required for series connection to be stably formed in a narrow width at the connection area, resulting in a reduction in the area of the connection area. , an increase in the active area as a solar cell can be obtained. In addition, in the present invention, since the cell dividing grooves and the electrode dividing grooves are closed with a closing resin layer made of electrically insulating resin prior to forming the connecting electrode layer, when forming the connecting electrode layer by a film forming method such as a screen printing method, It is possible to reliably prevent short-circuit accidents between the connecting electrode layer and the first electrode layer through the dividing grooves, and the yield is improved, which is very advantageous in terms of production. Further, if the resin is filled to the inside of the dividing groove, the width of the connecting portion can be narrowed and the yield can also be improved. Note that it is further advantageous in this respect if the resin of the closing resin layer is opaque to the laser beam used. Hereinafter, the structure and manufacturing method of the amorphous solar cell of the present invention will be explained in detail with reference to FIG. As the electrically insulating substrate 1 of the present invention, any substrate made of an electrically insulating material can be used, and specifically, a polymer film, a ceramic plate, a glass plate, or a metal foil with an insulating layer provided on the surface can be used. However, preferably by a roll-to-roll method, the constituent layers can be deposited one after another on a long running substrate;
A polymer film suitable for mass production is used.
The polymer film may be any polymer film that has the heat resistance necessary for amorphous silicon deposition, but polyethylene terephthalate (PET) film, polyethylene naphthalate film, and polyimide film, which have excellent mechanical properties, are preferably used. etc. are used. Then, as shown in FIG. 1A, a first
The electrode layer 2 and the amorphous semiconductor layer 3 of the photovoltaic layer are deposited uniformly. As this first electrode layer 2, a translucent electrode or a normal metal electrode is used depending on the overall configuration, as is well known. As the light-transmitting electrode, various known metal oxide layers or laminated structures of metal thin layers and dielectric layers are used. As the metal electrode layer, A, Ag, Ti, W, Co, Cr, Ni, nichrome,
Single-layer films or multi-layer films of single metals such as stainless steel or alloy metals are used. Preferably A having high light reflectivity and good bonding characteristics with the amorphous semiconductor layer.
/A laminated structure film of stainless steel layers is used. Note that this film thickness is desirably 0.3 μm or more from the viewpoint of reducing electrical resistance and mechanical strength. The amorphous semiconductor layer 3 uniformly provided on the metal electrode layer 2 is not particularly limited as long as it is an amorphous silicon layer having photovoltaic ability. There are pin-shaped amorphous silicon photovoltaic layers formed using the plasma CVD method using glow discharge decomposition.
The amorphous silicon photovoltaic layer may not only include a multilayer tandem structure such as pin/pin, pin/pin/pin, but also a narrow band gap or amorphous silicon germanium, amorphous silicon carbide, etc. A wide bandgap amorphous silicon semiconductor layer can also be used as appropriate. Next, the obtained continuous film amorphous solar cell is divided into unit cells by a laser beam irradiation method, and patterned resin layers 4a and 4b made of electrically insulating resin to enable electrical connection are formed as shown in FIG. 1B. As shown in FIG. 2, the semiconductor layer 3 is provided on the amorphous semiconductor layer 3 in the following manner. That is, the patterned resin layers 4a and 4b are patterned into a divided pattern on the amorphous semiconductor layer 3 and provided using a screen printing method or the like. In addition, Figure 2 is a 10cm x 10cm large-area continuous cell.
The dividing pattern, that is, the pattern resin layer 4a, when creating an integrated module M in which three unit cells C are formed and connected in series with a size of
4b is shown, and it goes without saying that the present invention is not limited thereto. Further, the patterned resin layers 4a and 4b may be provided between the first and second electrode layers due to their functions, and instead of this example, they may be provided on the first electrode layer 2, and then the amorphous semiconductor layer 3 is provided. It may be provided. By the way, the patterned resin layers 4a and 4b need to be provided with a width slightly wider than the dividing width of the laser beam so as to prevent short circuits on the dividing surfaces after the dividing process using the laser beam. In addition, if the layer thickness is less than 1 μm, short circuit between the first electrode layer 2 and the second electrode layer 5 described below cannot be prevented, and if it is more than 50 μm, a step will occur and the deposition of the second electrode layer 5 and post-processing will be difficult. Difficulty arises in forming connection electrodes and collection electrodes. Epoxy resin, polyamide resin, polyimide resin, polyester resin, etc. can also be used as the electrically insulating resin layer forming the patterned resin layers 4a, 4b. Patterned resin layers 4a and 4b
It is convenient in terms of production if both are made of the same resin. In addition, when providing on the said interface, a screen printing method, a coating method, etc. can be applied. Further, it is preferable that the patterned resin layers 4a and 4b are opaque to the laser beam used for division. When the resin layer is opaque, by selecting the power of the laser beam, it is possible to selectively cut the surface layer only on the laser irradiation side and cut the front and back layers including the opposite side. Next, a second electrode layer 5 is deposited uniformly over the entire surface of the substrate as shown in FIG. 1C. As the second electrode layer 5, a transparent electrode layer is used when the first electrode layer 1 is a metal electrode layer, and a metal electrode layer is used when the first electrode layer is a transparent electrode layer. As such a metal electrode layer and a transparent electrode layer, those described above for the first electrode layer can be applied as they are. Next, in order to convert the obtained continuous film solar cell into a module M and a unit cell C, a predetermined laser beam is scanned over the dividing pattern shown in FIG.
to be drilled. As long as the laser has a wavelength range that can be absorbed by each constituent layer, a laser with a wavelength of 0.2 to 2 μm is used, but YAG lasers, which are currently widely used industrially, are preferably used. . In addition, the laser beam power is
Cut all the metal electrode layer/amorphous silicon layer/insulating layer/transparent electrode layer along a to form a unit cell C.
The optimum power is selected depending on the case of forming the cell dividing groove 6 that divides into two, and the case of forming the electrode dividing groove 7 that divides the connection part A by cutting only the transparent electrode layer along the patterned resin layer 4b. , divided into parts. In addition, as is clear from FIG. 2, the electrode dividing groove 7
are provided along the cell division grooves 6 between adjacent unit cells C so as to form therebetween a connecting portion A consisting of each layer of the first electrode layer/amorphous semiconductor layer/divided second electrode layer. The connecting portion A does not need to be provided over the entire length of the cell dividing groove 6; in this case, the electrode dividing groove 7 may be provided along the connecting portion A depending on the shape of the connecting portion A.
is provided so as to be separated from the second electrode layer of the unit cell C. Next, as shown in FIG. 1E, the cell dividing grooves 6 and the electrode dividing grooves 7 formed by laser beam irradiation are filled with electrically insulating resin by screen printing, coating, etc. to form a closing resin layer 8. is formed. As the electrically insulating resin forming the closing resin layer 8, the resin of the patterned resin layers 4a and 4b described above can be applied as is. Next, on the second electrode layer 5, a collecting electrode 9 and a connecting electrode layer 10, 1 having a pattern as shown in FIG.
As shown in FIG.
are provided by a screen printing method to connect them. In this example, the connection electrode layer 10 serves as a bus bar for the collection electrode 9. The collecting electrode 9 and the connecting electrode layers 10 and 10' are made of Ag, Au, Ni,
A metal layer mainly composed of Cu, A, or Cr or a conductive resin layer in which these metals are dispersed in resin is used. Of course, these metals can be patterned and deposited using a vacuum evaporation method, but a conductive resin layer in which a conductive resin in which these metals are dispersed in a resin is formed by a screen printing method is preferable from the viewpoint of productivity. . The connection electrode layers 10 and 10' are shown in FIG.
As shown in FIG. 2, a connecting portion A is provided between a cell dividing groove 6 which has been divided into all layers by laser beam irradiation and an electrode dividing groove 7 which has only divided the second electrode layer 5.
Note that the connection electrode layer 10' serves as a current extraction electrode. Then, the laminate of the first electrode layer/amorphous semiconductor layer/second electrode layer/connection electrode layer of the connection part A is irradiated with laser light to melt and mix the laminate, and then solidified by natural cooling or the like. By laser welding, as shown in FIG. The two electrodes are electrically connected. The laser light may be irradiated from the connection electrode layer side, or if the insulating substrate is transparent to the laser light, it can be irradiated from the substrate side. Note that it is not necessary to weld the entire surface of the joint, as a sufficient electrical connection can be obtained with a suitable number of spot welds. The integrated amorphous solar cell obtained as described above is sealed with a resin or the like, as is well known, and then manufactured into a product. As described above, according to the present invention, an amorphous solar cell with good area efficiency can be obtained, and the amorphous solar cell can be integrated only by a processing process using a laser beam irradiation method after laminating an amorphous semiconductor layer. It can be manufactured with very high yield and productivity. In particular, it is preferable to carry out each of the above-mentioned steps using a long polymer film as a substrate by the Rolls roll method.
In addition, in the above second invention, each step may be performed separately, or some of them may be combined and performed simultaneously, and the order may be changed if possible. The present invention will be explained below with reference to Examples. [Example] A 100 μm thick polyester film (PET) was used as the electrically insulating substrate 1. First, the film substrate is mounted on a DC magnetron butterfly device,
The ^aluminum layer (A
) 0.4 μm and a stainless steel layer (SS) of 100 Å were successively deposited, and a highly reflective metal electrode layer 2 was provided on the long film substrate 1 as the first electrode layer 2 . Furthermore, a pin-type photovoltaic layer of amorphous silicon is deposited as an amorphous semiconductor layer 3 on this PET/A/SS deposited body by a roll-to-roll method disclosed in Japanese Patent Application Laid-Open No. 59-34668. It was long and deposited continuously over a large area. In order to form an integrated solar cell module in which three are connected in series on the same substrate, black insulating epoxy resin is coated with PET/A/SS/ as patterned resin layers 4a and 4b in the basic pattern shown in Fig. 2.
It was provided on the amorphous semiconductor layer using a screen printing method to have a width of 2 mm and a thickness of 12 μm. Note that the width of the connecting portion A was 2 mm. Next, as the second electrode layer 5, a transparent electrode layer made of indium oxide (ITO) was deposited uniformly to a thickness of about 600 Å using electron beam evaporation to fabricate a continuous cell. Next, a Q-switch type YAG laser beam is scanned over the patterned resin layer 4a shown in Figure 2 to cut the entire continuous cell consisting of A/SS/amorphous silicon/insulating layer/ITO layer, as shown in Figure 1D. Cell dividing grooves 6 as shown were bored. At this time, the Q switch frequency is 2KHz, the peak power of the laser light pulse is 2KW, and the scanning speed is 32
mm/sec. Further, the peak power of the laser beam was reduced to 200 W, and the insulating layer 4b in FIG. 2 was scanned under the same conditions except for the ITO
By cutting only the layer, the electrode dividing groove 7 shown in FIG. 1D is formed.
was drilled to form the connection part A. Then, as shown in FIG. 1E, a closing resin layer 8 made of black epoxy resin was formed thereon by screen printing to fill the cell dividing grooves 6 and electrode dividing grooves 7 with a width of 2 mm and a thickness of 12 μm. Then,
A collecting electrode 9 and connecting electrode layers 10, 10' having the pattern shown in FIG. 3 were formed using a screen printing method as follows. In other words, polyester-based Ag
A collection electrode 9 and a connecting electrode layer 10, 1 with a thickness of 15 μm are formed by screen printing conductive resin and drying it.
I got 0'. Next, on the connection electrode layers 10, 10'
By intermittently irradiating and scanning a YAG laser beam with a peak power of 2KW, an ohmic connection laser weld 11 is formed between the first electrode layer 2 and the connection electrode layers 10 and 10'. A three-series integrated solar cell module was formed. As a result of measuring this module under an AM-1, 100 mW/cm ² solar simulator, good battery characteristics as shown in Table 1 were obtained, confirming the effectiveness of the present invention. 【table】

[Brief explanation of the drawing]

1A to 1G are side sectional views showing the configuration of the embodiment of the present invention and the process of forming the same, and FIG. 1F is the third
FIG. 2 is a plan view illustrating the insulating layer formation pattern for forming the module of this example, and FIG. 3 is a partial side sectional view taken along the line A-B in this example. FIG. 3 is a collector electrode and connection electrode of the module of this example. FIG. 3 is a plan view showing a pattern of layers. DESCRIPTION OF SYMBOLS 1... Substrate, 2... First electrode layer, 3... Amorphous semiconductor, 4... Patterned resin layer, 5... Second electrode layer, 6... Cell dividing groove, 7... Electrode dividing groove, 8...
... Closing resin layer, 9 ... Collection electrode, 10 ... Connection electrode, 11 ... Laser welding part.

Claims (1)

[Scope of Claims] 1 A plurality of divided unit cells each consisting of a first electrode layer, an amorphous semiconductor layer, and a second electrode layer provided in a stacked manner on an insulating substrate are separated into adjacent unit cells. In an amorphous solar cell in which a first electrode layer and a second electrode layer are sequentially electrically connected, a laser beam is applied along a cell dividing groove formed by a laser beam irradiation method to divide the cell into unit cells and a cell dividing groove between adjacent unit cells. An electrode dividing groove that divides the second electrode layer by a light irradiation method and forms a connection part between the second electrode layer and the cell dividing groove; and a closing resin layer made of an electrically insulating resin that closes the cell dividing groove and the electrode dividing groove. , a connecting electrode layer that electrically connects the second electrode layer of one unit cell of the adjacent unit cells and the connecting part of the other unit cell provided across the cell dividing groove, and a connection formed at the connecting part by laser welding. What is claimed is: 1. An amorphous solar cell comprising: a welding portion electrically connecting an electrode layer and a first electrode layer and electrically connecting unit cells. 2 along the cell dividing groove and the electrode dividing groove.
The amorphous solar cell according to claim 1, wherein a patterned resin layer made of an electrically insulating resin is formed between the electrode layer and the second electrode layer. 3. The amorphous solar cell according to claim 2, wherein the patterned resin layer is opaque to the laser beam used for forming the dividing grooves. 4. The amorphous solar cell according to claim 1, 2, or 3, wherein the closing resin layer is opaque to laser light for laser welding. 5 A plurality of divided unit cells each consisting of a first electrode layer, an amorphous silicon layer, and a second electrode layer provided in a stacked manner on an insulating substrate are connected to the first electrode of one of the adjacent unit cells. In the method for manufacturing an amorphous solar cell in which a cell and a second electrode layer of the other unit cell are sequentially electrically connected, a first electrode layer, an amorphous silicon layer, and a second electrode cell are sequentially laminated on the insulating substrate. After forming a continuous cell, the amorphous solar cell is divided into unit cells according to the steps (a) to (e) below, and then the divided unit cells are electrically connected and integrated. Production method. (a) A step of scanning the cell division pattern to be divided into unit cells with a first laser beam to form cell division grooves that cut all layers of continuous cells, and dividing the cells into unit cells. (b) A second laser beam is used to scan an electrode division pattern that forms a connection part along the cell division pattern between unit cells to be connected, and an electrode division groove is formed to cut the second electrode layer to form each unit cell. The process of forming a connection part. (c) A step of forming a closing resin layer made of electrically insulating resin to close the cell dividing groove and the electrode dividing groove. (d) Step of forming a connection electrode layer that connects the second electrode layer of one unit cell and the second electrode layer of the connection portion of the other unit cell by straddling the cell dividing groove between adjacent unit cells. (e) A step of electrically connecting the first electrode layer and the connection electrode layer of the connection part by laser welding the connection part by irradiating the third laser light to the connection part. 6. Claim 5, wherein a patterned resin layer made of electrically insulating resin is formed between the first electrode layer and the second electrode layer in accordance with the division pattern and the electrode division pattern when forming continuous cells. The method for manufacturing the amorphous solar cell described above. 7. The method of manufacturing an amorphous solar cell according to claim 6, wherein the patterned resin layer is opaque to the first and second laser beams. 8. Claim 6 or 7, wherein the patterned resin layer is formed by a screen printing method.
1. Method for manufacturing an amorphous solar cell as described in Section 1. 9. The method for manufacturing an amorphous solar cell according to claim 5, 6, 7, or 8, wherein the closing resin layer is formed by a screen printing method. 10. The method of manufacturing an amorphous solar cell according to claim 9, wherein the closing resin layer is opaque to the third laser beam. 11 The connection electrode layer is Ag, Au, Cu, Ni, Al,
11. The method of manufacturing an amorphous solar cell according to claim 5, wherein the layer is mainly composed of Cr and is formed by a screen printing method. 12. The method for manufacturing an amorphous solar cell according to any one of claims 5 to 11, wherein the insulating substrate is a polymer film.