JPS61187377A - Dividing method for processing of amorphous solar battery - Google Patents

Abstract

PURPOSE:To prevent a dividing surface from shortcircuiting by forming a pattern made of an electrically insulating polymer resin layer on a boundary between a metal electrode layer and an amorphous Si semiconductor layer or a boundary between the amorphous Si semiconductor layer and a transparent electrode. CONSTITUTION:A polymer film is used as a substrate 1, and a metal electrode layer 2 made of an aluminum layer 2a and a stainless steel layer 2b is provided thereon. An amorphous semiconductor layer 3 by a glow discharge decomposing method is accumulated on the layer 2. Then, an epoxy resin is screen printed in a pattern shape on the layer 3 to form a polymer resin layer 5, and a transparent electrode layer 4 is then accumulated. An obtained cell is scanned by a YAG laser on the layer 5 to form a groove 6, and divided. The layer 5 is interposed to prevent the layer 4, the layers 3, 2 crystallized by a laser light from shortcircuiting to prevent the battery characteristic after dividing from decreasing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a method for dividing an amorphous solar cell into cells having a predetermined shape 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. Various substrates such as glass, polymer films, ceramic plates, and metal foils can be used. Since it can be selected, it is widely studied as a semiconductor film for solar cells. The basic structure of an amorphous silicon solar cell is an 8I metal electrode layer/amorphous silicon semiconductor layer/transparent electrode layer provided on the various substrates mentioned above.
The layered structure is known.

Taking advantage of the characteristics of amorphous silicon layer deposition, it is easy to install a solar cell 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. It is not possible to obtain an output voltage of more than 100V, which is required for this purpose. In order to obtain such a practical voltage, there are two methods: 1. A method in which a predetermined number of small-area solar cells are placed on a small-area substrate, and then a predetermined number of these cells are connected in series; A method of dividing a solar cell into cells with a predetermined small area by etching or the like without damaging the substrate, and then connecting a predetermined number of the cells in series. A method is known in which solar cells of a small area are deposited and then a predetermined number of the cells are connected in series. Among these methods, method (■) is not suitable for large-scale production that takes advantage of the characteristics of amorphous silicon layer deposition;
Moreover, the process of connecting in series and the process of modularizing become complicated. Method (2) is possible by a combination of resist coating and etching, but resist coating, exposure,
It requires many steps such as cleaning and etching, and is not suitable for producing large quantities of solar cells at low cost. With method (2), the solar cell constituent layers are generally deposited one after another by placing a metal mask in close contact with the substrate, but in the case of a large area, due to the difference in thermal expansion coefficient between the substrate and the mask, each layer is deposited on the substrate. If this happens, the adhesion of the mask will deteriorate, and the deposited components will often wrap around in each layer, making it impossible to obtain a good divided pattern. In addition, in the case of division by the mask deposition method, it is difficult to align the mask, and the error is 0.511 II.
It is difficult to reduce the size to less than +.

[Objective of the Invention] The present invention has been made to solve the above-mentioned drawbacks of the conventional method, and is capable of manufacturing a large-area amorphous solar cell on a large-area substrate using a simple process and at high speed without damaging the substrate. An object of the present invention is to provide a method for dividing an amorphous solar cell that can be divided into arbitrary shapes.

[Structure and operation of the invention] That is, the present invention provides a laminated structure of a metal electrode layer, an amorphous silicon semiconductor layer, and a transparent electrode layer, in which an amorphous silicon semiconductor layer is used as a photovoltaic layer, on a substrate. When dividing the amorphous solar cell into predetermined patterns by irradiating laser light onto the surface of the amorphous solar cell and moving the irradiation point along a predetermined pattern, the metal electrode of the pattern is preliminarily cut. The amorphous thick! j!
This is a method for dividing batteries.

The above-mentioned present invention was made as follows.

In the division processing method using laser light, by adjusting the optical system, the width of the division part can be changed freely between several tens of microns to several hundred microns, and by using a computer control method, it is possible to change the width of the division part to a predetermined width by adjusting the optical system. By programming the pattern, it is possible to divide into arbitrary shapes accurately and with good reproducibility. Furthermore, by moving mirrors within the optical system or using optical fiberglass, it is possible to divide solar cells on a continuously running wide substrate film, making it possible to realize a dividing process with high overall productivity.

Therefore, when we irradiated laser light and processed it into parts, we found that simply scanning the laser light along a predetermined pattern and patterning would cause thermal damage to the area around the light irradiated area, especially for amorphous silicon layers. It was revealed by Raman spectroscopy that this phenomenon occurs. When the silicon layer crystallizes, the dark conductivity of that part increases and the pi
It loses its n-junction characteristics and no longer exhibits rectifying action. Therefore, it was found that the electromotive force generated in the solar cell was lost in the crystallized region, resulting in a decrease in the solar cell characteristics after patterning.

Furthermore, as a result of electron microscopy observation of the split area, it was observed that the lower metal electrode and the upper transparent electrode layer were melted and bonded, which was also found to be a cause of deterioration of the solar cell characteristics. .

An example of this is shown in ◎ in Figure 2. As a result of examining various solutions to this problem, we found that high electrical insulation is required between the amorphous silicon semiconductor layer and the metal electrode layer or between the amorphous silicon semiconductor layer and the transparent electrode layer of the amorphous solar cell. We have discovered that by interposing a molecular resin layer, it is possible to prevent short circuits between the transparent electrode layer and the crystallized amorphous silicon semiconductor layer and the metal electrode layer, and to prevent the deterioration of solar cell characteristics after division,
The present invention has been achieved.

By the way, in the above study, the present inventors made the above polymer resin layer opaque to laser light,
It was discovered that when the power of the laser beam is set to high, the gold layer can be cut, and when the power is set to low, only the layer located on the laser irradiation side of the polymer resin layer can be cut. Therefore, by providing an opaque polymer resin layer, it is possible to selectively cut the surface layer only on the irradiated side and cut the front and back layers including the opposite side by simply changing the power of the laser beam, allowing two types of patterning to be performed in one layer. will be possible.

The present invention will be explained in detail below.

From the above point, the electrically insulating polymer resin layer formed along the pattern needs to be provided with a width slightly wider than during the laser beam division so that short circuits on the dividing surface can be prevented after the laser beam division process. In addition, the thickness of the polymer layer is 1 μm
Below is a metal electrode layer.

Short circuits between the transparent electrodes 1 cannot be prevented, and if the thickness is 50 μm or more, a step will occur, making it difficult to deposit the transparent electrode layer and form the collecting electrode in a subsequent step.

The polymer resin layer is an epoxy resin.

Polyamide resin, polyimide resin, polyester resin, etc. can also be used. In addition, when providing on the interface, a screen printing method or the like can be applied.

Further, the cough polymer resin layer may be transparent or opaque to laser light. When cutting and dividing layers including the polymer resin layer on the side opposite to the laser irradiation side, a transparent material has the advantage that the power of the laser beam required is smaller. On the other hand, when the polymeric resin layer is opaque, there is an advantage that selective cutting can be performed by selecting the power of the laser beam to selectively cut the surface layer only on the laser irradiation side and cut the front and back layers including the opposite side. In the above-mentioned amorphous solar cell, only one polymer resin layer is provided between the transparent electrode layer and the electromotive force layer according to a predetermined pattern, and the pattern is divided up to the metal electrode layer and only the transparent electrode layer is separated. It is possible to divide patterns, which has a very large effect on patterning and modularization.

In any case, when dividing with a laser, it is possible to divide into any shape by selecting the optimum power.

As the laser, light with a wavelength of 0.2 to 2 μm is preferably used as long as it is in a wavelength range that can be absorbed by each of the constituent layers, but YAG laser, which is currently widely used industrially, is preferably used.

Incidentally, the amorphous solar cell to which the present invention can be applied is not particularly limited, and may be one having an amorphous silicon semiconductor layer as an electromotive force layer, but from the viewpoint of productivity, an electrically insulating substrate, more preferably a flexible solar cell may be used. It is preferable that the film be continuously formed on a flexible elongated substrate.

In addition, the divided amorphous solar cells were heated at 120°C to 2°C.
Heat treatment in air at 00° C. has the effect of preventing deterioration in performance of the solar cell after division, and it is preferable to perform the heat treatment after division.

The present invention will be explained below based on examples.

FIG. 1 is a side sectional view of an amorphous silicon solar cell according to an example. In this example, a polymer film suitable for mass production is used as the substrate 1, in which the solar cell constituent layers can be sequentially deposited on a long running substrate by a roll-to-roll method. The polymer film may be any polymer film that has the heat resistance necessary for amorphous silicon deposition, but polyethylene nalphthalate (PET) film, polyimide film, etc. are preferably used. The example shown uses PET film.

A1 layers 2a and 30 with a thickness of about 0.5 μm are used as the gold a electrode layer 2.
An An/stainless steel laminate in which approximately 0 to 10 stainless steel layers 2b were sequentially deposited using a sputtering method was used.

The amorphous silicon semiconductor layer 3 of the photovoltaic layer is a well-known pin
The film was deposited on the metal electrode layer 2 using a glow discharge decomposition method using silane gas, etc., similar to that disclosed in Japanese Patent Application Laid-Open No. 59-34668.

Next, as the electrically insulating polymer resin layer 5 provided at the interface between the amorphous silicon semiconductor 3 and the transparent electrode layer 4, epoxy resin is divided into parts on the amorphous silicon semiconductor layer 3 using a screen printing method using a laser. 10 in the predetermined pattern shape
It was provided with a thickness of μm.

Next, an indium oxide (ITo) layer is deposited as a transparent electrode layer 4 by electron beam evaporation or sputtering.
PET/An/SU deposited on about 00 people and shown in Figure 1.
An amorphous solar cell having an epoxy resin FM/ITO structure patterned with S/amorphous silico 7p;n7 was obtained.

Note that the amorphous silicon thick i battery is not limited to the above-mentioned structure, and for example, a ceramic plate may be used as the substrate 1.

A glass plate or a metal foil provided with an insulating layer on the surface can be used, and a long flexible substrate that can be used for continuous film formation, division, and processing is particularly advantageous. Moreover, the metal electrode layer 2 provided thereon is also made of Ti, 80 yen.

Single metals and alloy metals such as W, Pt 2 , Ni 2 , Go 2 , chromium, and nichrome can be used. Moreover, as the structure of the amorphous silicon semiconductor layer 3 of the electromotive force layer, in addition to pin, pan
In addition to multilayer tandem structures such as /ptn, pin /Din 7prn, narrow bandgap or wide bandgap amorphous silicon semiconductor layers such as amorphous silicon germanium and amorphous silicon carbide can also be used as appropriate. . Furthermore, transparent electrode I
! As i4, a known transparent monoelectric layer such as tin oxide or cadmium stannate can be used.

Next, the PET/A pattern/SUS/amorphous silicon PTN/patterned epoxy resin layer/I shown in FIG.
A 10aRX101 square cell of an amorphous solar cell with a TO structure is scanned with a YAG laser over the electrically insulating polymer resin layer 5 made of an epoxy resin layer to melt and evaporate the solar cell components to form a metal layer as shown in Figure 1. A groove 6 up to the electrode layer 2 was formed to divide the cell into two 5CrR×10 square cells. Furthermore, Y
The AG laser is a Q-switched pulsed laser with an average laser power of 0.8W and a pulse frequency of 2 K I-I Z
Then, irradiate the surface of the solar cell at a speed of 80cm/5eIC.
I scanned it with

The current-voltage characteristics of the 5cz x 10α square cell after division are as follows:
It was B in the diagram. A in the same figure is 10c before division, Xl 0
C is the characteristic of a cm square cell, where C is a conventional amorphous solar cell with the same configuration as the above example but without a polymer resin layer;
This is the characteristic of a comparative example divided by AG laser.

From the figure, it is clear that according to the present invention, it is possible to divide the cell without substantially degrading the cell performance.

Further, when the divided cell of Example was heat-treated in air at 150° C. for 30 minutes, it had the same characteristics as the cell before dividing as shown in FIG. 3. It was confirmed that almost the same results could be obtained up to 200°C.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the solar cell used in the example. FIG. 2 is a graph of voltage-current characteristics of a solar cell showing the results of an example. 1: Substrate 2: Metal electrode layer 3: Amorphous silicon semiconductor layer 4: Transparent electrode layer 5: Electrically insulating polymer resin layer Figure 2

Claims (6)

[Claims] (1) An amorphous solar cell in which a laminated structure of a metal electrode layer, an amorphous silicon semiconductor layer, and a transparent electrode layer is formed on a substrate, with an amorphous silicon semiconductor layer as a photovoltaic layer, is fixed with a laser beam. When dividing into patterns, an electrically insulating polymer resin layer is formed in advance at the interface between the metal electrode layer and the amorphous silicon semiconductor layer or the interface between the amorphous silicon semiconductor layer and the transparent electrode layer of the pattern. A method for dividing an amorphous solar cell, which is characterized by: (2) The method for dividing an amorphous solar cell according to claim 1, wherein the polymeric resin layer is opaque to laser light. (3) The thickness of the insulating polymer resin layer is 1μ or more and 50μ
A method for dividing an amorphous solar cell according to claim 1 or 2 below. (4) Heat the amorphous solar cell after splitting to 120°C to 200°C.
Claims 1 and 2, in which heat treatment is performed in air at ℃
The method for dividing an amorphous solar cell according to item 1 or 3. (5) The method for dividing an amorphous solar cell according to claim 1, 2, 3, or 4, wherein the amorphous solar cell is formed on an insulating substrate. (6) Claims 1, 2, and 3, wherein the amorphous solar cell is continuously formed on a long flexible substrate.
The method for dividing an amorphous solar cell according to item 4 or 5.