JPS61214483A - Manufacture of integrated type solar cell - Google Patents

Abstract

PURPOSE:To join electrodes for connecting good conductive materials with a metallic electrode surface by a method wherein the electrodes for connection are formed onto each cell according to predetermined patterns, electrode sections are irradiated by laser beams, the whole layer is melted and a metallic electrode layer and the electrodes for connection are joined in an ohmic manner. CONSTITUTION:When two metallic layers 2 formed while holding an amorphous silicon semiconductor layer 3 are irradiated by laser beams and the metallic layers 2 are melted including the amorphous silicon semiconductor layer 3, the central section of irradiation is evaporated to some extent, but an excellent ohmic junction is shaped between both metallic layers 2. A layer mainly comprising either of gold, silver, copper, Al or nickel or these alloy is applied as a collection electrode or a good conductive electrode for connection as an electrode layer for connecting cells. The electrode for connection is shaped onto a transparent electrode layer patterned by employing a physical method, such as a vacuum deposition method, a sputtering method, etc. It is preferable that the film thickness of a thin film at that time extends over 0.5mum or more. Even beams within a wavelength range which several constitutional layers can absorb may be used as laser beams, and a YAG laser is employed preferably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a method for manufacturing an integrated amorphous silicon thin film solar cell. More specifically, they are stacked on the same substrate,
Multiple compartmentalized metal electrode layers.

The present invention relates to a method for manufacturing an integrated solar cell in which a cell consisting of an amorphous silicon layer and a transparent electrode layer is connected.

[Prior art 1] Amorphous silicon semiconductor films can be deposited uniformly over a wide area at low substrate temperatures by using silane gas or other gas discharge decomposition methods. Because the substrate can be selected, it is widely studied as a semiconductor film for solar cells.

The basic structure of an amorphous silicon solar cell is a laminated structure of metal electrode layer/amorphous silicon semiconductor layer/transparent electrode layer provided on the various substrates mentioned above.

Utilizing the characteristics of amorphous silicon layer deposition, JP-A-59-34
The roll-to-roll method disclosed in 668M publication and Ja
pan Journal of Applied
Physics magazine, Vol. 21, No. 3, page 413 (198
It is easy to deposit an amorphous silicon layer on a large-area elongated substrate provided with a metal electrode layer using the three-chamber separation formation method described in 2).

Further, it is also easy to provide the transparent electrode layer of the other current extraction electrode over a large area. However, in order for the above-mentioned laminate to function as a solar cell, it is necessary to attach lead terminals to the metal electrode layer and the transparent electrode layer. Furthermore, in order to obtain an output voltage of several tens of volts or more, which is necessary for practical use, it is necessary to divide the large-sized battery formed on the large-area substrate using a laser scribing method, etc., and then connect adjacent metal electrode layers. It is necessary to connect the transparent electrode layer in series. In such a case, a method is usually used in which the lowest metal electrode layer is exposed and then connected to the adjacent upper electrode layer or lead extraction electrode. Methods for exposing this metal electrode layer include: ■ using a metal mask during deposition of the amorphous silicon layer; ■ removing the silicon layer using wet or dry etching after depositing the amorphous silicon layer; and ■ removing the silicon layer using a wet or dry etching method after depositing the amorphous silicon layer. A method has been used in which after depositing a silicon layer, only the silicon layer is selectively melted and evaporated by laser irradiation to remove it.

Among these methods, method (2) is not only unsuitable for long, large-area roll-to-roll methods, but also in the three-chamber separation method, the heating process during amorphous silicon deposition causes heat loss between the substrate and mask. Due to poor adhesion due to the difference in expansion rate,
The amorphous silicon component wraps around, making it impossible to obtain a good pattern, and it is difficult to expose the electrically good surface of the metal layer.

Method (2) is possible by combining resist coating and etching, but resist coating and B light.

It requires many steps such as cleaning and etching, and is not suitable for producing large quantities of solar cells at low cost.

In addition, in method (2), the high temperature required to melt the silicon layer damages the metal electrode layer using a high-melting point metal, making it impossible to expose the electrically good surface of the metal layer. The reality is that it is not possible to selectively remove only the silicon layer with low melting point metals such as.

1. Purpose of the Invention] The present invention solves the above-mentioned drawbacks by bonding connection electrodes to the gold 8 electrode surface for taking out lead terminals on a large-area substrate or connecting divided solar cells in series. The purpose of this invention is to provide a simple method for manufacturing an integrated solar cell.

[Structure and operation of the invention] The above objects are achieved by the invention as follows.

That is, the present invention provides an integrated solar cell in which cells are laminated on the same substrate and are composed of a plurality of partitioned metal electrode layers, an amorphous silinco semiconductor layer serving as a photovoltaic layer, and a transparent electrode layer. In the manufacturing method, after forming a connection electrode made of a highly conductive material in a predetermined pattern on each hill, the electrode portion is irradiated with laser light to melt the entire layer, thereby bonding the metal electrode layer and the connection electrode. This is a method for connecting thin film solar cells, which is characterized by ohmic contact.

As a result of various studies in order to eliminate the above-mentioned drawbacks of the conventional method, the present invention described above was developed by irradiating a laser beam onto two metal layers sandwiching an amorphous silicon semiconductor layer, thereby forming an amorphous silicon semiconductor layer. This was done based on the discovery that when the metal layers are melted, a good ohmic bond is formed between the two metal layers, although the irradiated center portion evaporates slightly. The present invention
As mentioned above, simply form the connection electrodes at the connection points,
Since it is only necessary to irradiate the laser beam, there is no need for the step of exposing the metal electrode surface as in the conventional method, and electrical connection with the metal electrode surface can be formed very easily and by a dry process.

It is unclear why laser light can electrically connect an amorphous silicon layer and a metal layer with a transparent electrode layer sandwiched therein, but as the amorphous silicon crystallizes by melting, the metal forming the metal layer It is believed that this was mixed in the entire layer, the electrical resistance of the laser beam irradiated cross section was reduced, and a good ohmic junction was formed.

The details of the present invention will be specifically explained below.

As the electrically insulating substrate 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, a metal foil with an insulating layer on the surface, etc. can be used. Preferably, however, a polymeric film is used which allows the constituent layers to be deposited one after another on a long, moving substrate by a roll-to-roll method and is suitable for mass production. The polymer film may be any polymer film that has the heat resistance necessary for amorphous silicon deposition, but preferably polyethylene terephthalate (PET) film, poly, ethylene naphthalate film, etc., which have excellent mechanical properties. A polyimide film or the like is used.

The metal electrode layer provided on the substrate is AU, A(1
The main component is a metal with good electrical conductivity and a melting point of 1000°C or less, such as -ri, w, pt, co, crt.
A laminated layer consisting of a single metal such as nichrome or stainless steel and a five-alloy metal thin film is used.

Further, it is desirable that these metal electrode layers have a thickness of 0.3 μm or more from the viewpoint of reducing electrical resistance and mechanical strength.

The amorphous silicon layer can be formed using any known photovoltaic layer, and is not particularly limited. Specifically, it can be formed using a plasma CVD method using glow discharge decomposition of a known silane gas, disilane gas, etc. There are pin-shaped laminated photovoltaic layers, etc.

In addition, as such an amorphous silicon photovoltaic layer, pi
Not only multilayer tandem structures such as n/pin and pin/pin/pin, but also narrow bandgap or wide bandgap semiconductor layers such as amorphous silicon germanium and amorphous silicon carbide can be used as appropriate.

Further, the transparent electrode layer is not particularly limited, and known ones can be used as they are, and various gold RI! l! compounds are preferably applied. Specifically, a metal oxide layer such as indium oxide, tin oxide, cadmium stannate, indium tin oxide, or a laminate of a metal i film and an oxide dielectric material is used.

Gold, silver, copper, and An are used as the connection electrode with good conductivity, which becomes the collecting electrode or the electrode layer for connecting the battery surface.

A layer based on any of nickel or alloys thereof is applied. This connection electrode is formed on the transparent bridge layer by patterning using a physical method such as a vacuum evaporation method or a sputtering method. Note that the thin film at this time has a thickness of 0.5μ
The above is preferable. Further, the connecting electrode can also be provided by a chemical method such as plating, and the film thickness in this case is the same as described above. Furthermore, a method of providing a conductive resin using fine powder of gold, silver, copper, AN, or nickel by screen printing or the like can be applied. This screen printing method is desirable from the viewpoint of continuous productivity. The printed conductive layer needs to have a thickness of 5 μm or more for electrical resistance.

As the laser beam, 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 constituent layer, but YAG laser, which is currently widely used industrially, is preferably used.

The laser beam is irradiated from above the above-mentioned connection electrode formed according to the connection pattern, but when the substrate is transparent to the laser beam, it can also be irradiated from the back surface of the substrate through the substrate according to the pattern.

The laser power depends on the irradiation direction and also depends on the thickness of the S conductive electrode layer, etc., and must be determined experimentally. , it is necessary to select a range in which all layers of the connection electrode layer are melted. Note that it is not necessary to melt the entire layer of the metal ff144 layer or the connection electrode layer, and it is sufficient to melt at least a portion of the amorphous silicon layer side.

Examples of the present invention are shown below.

[Example] A 100 μm thick polyethylene terephthalate film (PET) was used as the polymer film substrate 1. First, the film substrate 1 is mounted on a DC magnetron sputtering device, and aluminum 1lif (All) 0.4μ milk and stainless steel layer (S
S) Continuously deposit 100 metal electrode layers 2
was provided on the long film substrate 1 (see FIG. 3). Furthermore, a pin-type photovoltaic layer 3 of amorphous silicon is formed on the PET//l/SS deposited body in a long and large area by the roll-to-roll method disclosed in Japanese Patent Application Laid-Open No. 59-34668. Continuously boron (B) doped p1g130
0^, r m o, s μm, phosphorus (P) doped 0 layer 2
008. In order to form a solar cell in which three cells C are connected in series on the same substrate, a large-area PET/All/88/
A black insulating paste is printed on the laminate of amorphous silicon layers using a screen printing method according to the cell division pattern.
Electrical insulation WI4 was formed in accordance with the division pattern shown in the figure to prevent poor insulation between electrodes around the division grooves during division processing. Thereafter, a transparent electrode layer 5 made of indium oxide was uniformly deposited to a thickness of 600 mm by electron beam evaporation.

Next, by a laser scribing method using a YAG laser, three cells C of 3.3c IRX10α shown in FIG.
It was divided as follows. That is, the YAG laser has a Q-switch frequency of 2KH2 and a power (peak value output) of I.
KW, beam diameter 100μm, scanning speed 3.2α/5
e (i) to form a cell dividing groove 6 along the electrical insulating layer 4 in which all layers except the substrate 1 are evaporated for dividing the cell C, and a YAG laser is emitted along the electrical insulating layer 4a. Only the power was set to 150 W, and other conditions were the same as above, and only the transparent electrode layer 5 was evaporated to form an electrode division iR7 that separates the connection electrode part 5a, and the cells were divided.

After the division, silver conductive resin was deposited to a thickness of 13 μm in the following pattern shown in FIG. 2 using a screen printing method, and the collecting electrode 8 was
And a lead extraction electrode 9 was formed.

That is, the busbar part 8a of the collecting electrode 8 is located on the connection electrode part 5a so as to serve as a connection electrode, and the busbar part 8a is located on the connection electrode part 5a.
The finger portions 8b are arranged in a pattern starting from a at predetermined intervals in a direction perpendicular thereto.

Note that the bus bar portion 8a of the cell C on the right side in the figure serves as an electrode for lead extraction.

Next, in order to connect the three cells C in series, a YAG radar beam with a power of 2 KW and the same conditions as above was irradiated onto the buspar 8a of the collecting electrode 8 as shown in FIG. 3, and scanned over its entire length. did. By irradiating the laser beam, all the layers except the substrate were melted and mixed as shown in FIG. 3, and a good ohmic connection was formed between the metal electrode layer 2, the bus bar portion 8a, and the lead extraction electrode 9. This is a solar cell module in which the three cells C obtained above are connected in series.
This is clear from the results in Table 1, which were measured under a solar simulator of 00 mW/cd and AM 1.

For comparison, a solar cell module with the same configuration was made using the mask method in all steps, and the measurement results are also shown in Table 1.

(Hereinafter blank) Table 1 (Hereafter blank) As is clear from Table 1, the module using the manufacturing method of the present invention shows the same efficiency and fill factor as the mask method. This shows that a good ohmic connection is formed using this method.

Note that similar results were obtained when the same configuration as this example was used and the connection was made by irradiating laser light from the PET film side of the substrate. In this case, since it was not necessary to melt the entire silver layer of the bus bar portion 8a of the connection electrode, the power of the laser beam of 500 W was sufficient.

Note that other conditions for the laser beam in this case are the same as described above.

[Brief explanation of drawings]

FIG. 1 is a surface view showing the cell division pattern of the thick wAw1 cell used in the example, FIG. 2 is a plan view showing the collecting electrode pattern of the solar cell, and FIG. 3 is the solar cell taken along line A8 in FIG. FIG. 2 is a partial side sectional view showing the structure of FIG. 1: Substrate 2: Metal electrode layer 3: Amorphous silicon 5: Transparent electrode layer 8: Collection electrode 8a: Bus bar part of connection electrode

Claims (1)

[Claims] 1. An integrated solar cell in which cells are stacked on the same substrate and are made up of a plurality of partitioned metal electrode layers, an amorphous silicon layer serving as a photovoltaic layer, and a transparent electrode layer. In the manufacturing method, a connecting electrode made of a highly conductive material is formed in a predetermined pattern on each cell, and then laser light is irradiated to the electrode part to melt the entire layer, thereby forming a metal electrode layer and a connecting electrode. A method for manufacturing an integrated solar cell, characterized by making an ohmic contact between the two. 2. The method for manufacturing an integrated solar cell according to claim 1, wherein the connection electrode is a busbar portion of a collecting electrode. 3. The method for manufacturing an integrated solar cell according to claim 1 or 2, wherein the connection electrode is made of gold, silver, copper, aluminum, nickel, or an alloy thereof. 4. The metal electrode layer is a layer mainly composed of a highly conductive metal having a melting point of 1000°C or less, or a layer containing the highly conductive metal.
A method for manufacturing an integrated solar cell according to claim 1, 2, or 3, which comprises a laminate with a metal thin film having a melting point of 00° C. or higher. 5. The method for manufacturing an integrated solar cell according to claim 1, 2, 3, or 4, wherein the substrate is an electrically insulating material. 6. The method for manufacturing an integrated solar cell according to claim 5, wherein the substrate is a long polymer film.