JPH0620149B2 - Method of manufacturing thin film solar cell - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a thin film solar cell using an amorphous silicon layer as a photovoltaic layer. More specifically, it relates to a method for manufacturing a thin film solar cell in which a current extraction electrode is connected to a lower electrode layer of a lower electrode layer / amorphous silicon layer / upper electrode layer laminated on an insulating substrate.

[Prior Art] An amorphous silicon semiconductor film can be uniformly deposited on a wide area at a low substrate temperature by a glow discharge decomposition method using silane gas or the like, and various substrates such as glass, polymer film, ceramic plate and metal foil can be used. 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 various substrates is used.

Taking advantage of the characteristics of amorphous silicon layer deposition, the roll-to-roll method disclosed in Japanese Patent Laid-Open No. 59-34668 and Japan Joarn
al of Applied Physics, Volume 21, Issue 3, Page 413 (198
It is easy to deposit an amorphous silicon layer on a large-area long substrate provided with a metal electrode layer by using the three-chamber separation forming method described in 2).

It is also easy to provide the transparent electrode layer of the other current extraction electrode in a large area. However, it is necessary to attach lead terminals to the metal electrode layer and the transparent electrode layer in order to operate the above-mentioned laminated body as a solar cell. Further, in order to obtain an output voltage of several tens of volts or more required for practical use, the solar cell provided on the large-area substrate is divided by a laser scribing method or the like, and then the adjacent metal electrode layer and transparent electrode layer are formed. It is necessary to connect in series. In such a case, exposing the lowermost metal electrode layer is an essential requirement. This method uses a metal mask when depositing the amorphous silicon layer, removes the silicon layer using a wet or dry etching method after depositing the amorphous silicon layer, and uses laser irradiation after depositing the amorphous silicon layer. Methods such as selectively melting and vaporizing only the silicon layer to remove it have been used.

Among these methods, the method is not suitable for the roll-to-roll method of a long area and a large area, and even in the three-chamber separation formation method, the thermal expansion of the substrate and the mask during the heating process at the time of depositing the amorphous silicon. Due to the deterioration of adhesion due to the difference in rate,
It is difficult to expose the surface of the metal layer where an amorphous silicon component wraps around and a good pattern cannot be obtained and which is electrically good.

Although this method is possible by combining resist coating and etching, it requires a number of steps such as resist coating, exposure, cleaning, and etching, and is not suitable for manufacturing a large number of solar cells at low cost. In the other method, since the high temperature necessary for melting the silicon layer is generated, the metal electrode layer using the high melting point metal is damaged and the electrically good metal layer surface cannot be exposed. In reality, it is not possible to selectively remove only the silicon layer with a low melting point metal.

[Object of the Invention] The present invention has been made in view of the above situation, and a current extraction electrode for allowing lead terminals to be taken out on a large-area substrate or series connection of separated cells to be a lower electrode. It is an object of the present invention to provide a method for manufacturing a thin film solar cell that can be easily connected to a surface.

[Structure and Action of the Invention] The above-mentioned object is achieved by the present invention described below. That is, the present invention provides a lower electrode of a thin film solar cell in which a lower electrode layer, a photovoltaic layer made of an amorphous silicon layer, and an upper electrode layer are sequentially laminated on an electrically insulating substrate, and an electrode for current extraction is provided from above to the lower electrode. At the time of connection, a region electrically insulated from the upper electrode layer is formed on a part of the photovoltaic layer, and V reaches the lower electrode layer from the upper part by machining in the region.
A method for manufacturing a thin-film solar cell, characterized in that a groove or hole having a V-shaped cross section is provided, and the current extraction electrode made of a conductive resin electrically filled in the groove or hole and electrically connected to the lower electrode layer is provided. Is.

The present invention described above, in the region electrically insulated from the upper electrode layer formed in a part on the photovoltaic layer by machining, the photovoltaic layer of the lower electrode layer, and in some cases the upper electrode layer A groove or hole having a V-shaped cross section is formed by drilling to reach the lower electrode layer, and a conductive resin is embedded in the groove or hole to serve as an electrode for current extraction, and the above-described specific patterning is unnecessary. In addition, a desired electrical connection can be easily formed by a combination of machining and screen printing, and a manufacturing process with extremely high productivity and high yield is realized.

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

FIG. 1 is a side sectional view of an example of a thin-film solar cell which is the subject of the present invention.

In the figure, is an electrically insulating substrate, is a metal electrode layer of a lower electrode layer, is an amorphous silicon layer of an electromotive force layer, is a transparent electrode layer of an upper electrode layer, and is a well-known amorphous silicon thin film solar cell. Is shown. The present invention is not limited to what is shown in the drawings, and can be applied to a transparent electrode layer for the lower electrode layer and a metal electrode layer for the upper electrode layer, or a transparent electrode layer for both upper and lower electrode layers. .

By the way, as the electrically insulating substrate of the present invention, all substrates made of an electrically insulating material can be applied, and specifically, a polymer film, a ceramic plate, or a foil having an insulating layer on its surface can be used. Preferably, a polymer film is used which is capable of sequentially depositing constituent layers on a long running substrate by a roll-to-roll method and is suitable for mass production. As the polymer film, any polymer film having heat resistance necessary for depositing amorphous silicon may be used, but preferably polyethylene terephthalate (PET) film, polyethylene naphthalate film, polyimide film having excellent mechanical properties. Are used.

As the metal electrode layer used as the lower electrode layer or the upper electrode layer, Al, Ag, Ti, W, Pt, Ni,
A single layer film of a single metal such as Co, Cr, nichrome, stainless steel, or an alloy metal, or a multi-layer film is used, but an electrode layer containing Al or Ag as a main component is preferably used.
Further, the thickness of these metal electrode layers is preferably 0.3 μm or more from the viewpoint of reduction in electric resistance and mechanical strength.

The amorphous silicon layer is not particularly limited as long as it has a photovoltaic ability, but specifically, it is a pin formed by the plasma CVD method using glow discharge decomposition of already known silane gas, disilane gas, etc. Shaped photovoltaic layers and the like. The amorphous silicon photovoltaic layer may have a multi-layer tandem structure such as pin / pin or pin / pin, as well as a narrow bandgap or wide bandgap such as amorphous silicon germanium or amorphous silicon carbide. The semiconductor layer can also be used in a timely manner.

The transparent conductive layer used for the upper electrode layer or the lower electrode layer is not particularly limited, and any known material can be used. For example, an oxide conductor such as indium oxide, tin oxide, or cadmium stannate deposited by electron beam evaporation or sputtering can be used. Further, it can be applied to a thin film solar cell in which a transparent conductive film is bonded to the surface of the above-mentioned metal electrode layer / amorphous silicon layer laminate through a transparent conductive adhesive layer.

The machining may be performed as long as a groove or hole having a V-shaped cross section can be formed, but it is preferable to use a pointed processing member. As such a processing member, a knife, a needle-shaped body or the like can be used. Then, for example, by mechanically moving or striking these processed members on the amorphous Rincon layer, a groove or a hole reaching the lower electrode layer is formed. It is preferable to form a plurality of grooves or holes over the entire surface of a predetermined portion in order to reduce the resistance of electrical connection and increase reliability.

The contact pressure of the processing member during processing is preferably sufficient to remove the amorphous silicon layer and does not reach the electrically insulating substrate, and it is desirable to select the optimum value in each case.

For example, when processing the amorphous silicon layer on the lower metal electrode layer using a pointed processing member such as a knife after processing, the processing member is mechanically repeatedly moved on the amorphous silicon layer under a predetermined contact pressure. Then, as shown in FIG. 2 (A),
A plurality of V-shaped grooves can be formed and the lower metal electrode layer can be exposed on the side surfaces of the grooves. Next, the electrode for extracting electric current from the exposed metal layer portion is provided with a conductive resin layer on the V-shaped groove by a screen printing method or the like so that the lower electrode is provided with a groove through the groove as shown in FIG. 2 (B). Can be formed in a state of being electrically connected. Among them, the method of providing the conductive resin layer by the screen printing method is preferable from the viewpoint of the present invention because the step is performed in the atmosphere and without a mask. Here, since the shape of the groove or hole is the V-shaped cross section as described above, good electrical connection can be obtained in these manufacturing methods. The width of the opening is appropriately selected according to the method of forming the current extraction electrode. Even after the lower metal electrode layer / amorphous silicon layer / transparent electrode layer is deposited, the same method is used as compared with the lower metal electrode layer. Can be deposited.

[Example] As a substrate, a polyethylene terephthalate film (PET) having a thickness of 100 μm was used. First, the film substrate was attached to a magnetron sputtering apparatus, and an A of 10 ^-3 torr level was set.
An aluminum layer (Al) 0.4 μm and a stainless layer (SS) 100 Å were successively and successively deposited in an r atmosphere to provide a metal electrode layer on the long film substrate 1. Further, a pin type photovoltaic layer of amorphous silicon is continuously formed on the PET / Al / SS stack by a roll-to-roll method disclosed in Japanese Patent Laid-Open No. 59-34668. Deposited on. The above PET having a large area for forming a solar cell module in which three cells are connected in series on the same substrate.
/ Al / SS Amorphous silicon layer is screen-printed with an electrically insulating layer having a division pattern as shown by a black band B in FIG. 3, and then a metal mask is provided in a shaded area S in FIG. An indium transparent conductive layer was deposited.
Further, by a laser scribing method of irradiating the black belt B with a YAG laser, the cells were divided into three cells C having an area of 24.5 m ² along the division pattern.

The three disassembled cells C were connected in series as follows to obtain a solar cell module having an integrated structure. That is,
A stainless knife is used to expose the metal electrode layer in the region S where the transparent electrode layer shown in FIGS. 3 and 5 is not provided, that is, the region S insulated from the transparent electrode layer. In contrast to this, a V-shaped line having a width of several hundred μm is penetrated through the metal electrode layer / amorphous silicon layer while being vertically pressed and repeatedly moved in the horizontal direction while being pressed with a predetermined contact pressure. The grooves T were formed with a uniform density. Next, a silver paste layer having a pattern shown in FIGS. 4 and 5 was provided as a current extraction electrode P on the transparent conductive layer and the exposed metal electrode layer by screen printing, and the cells C were connected in series. That is, in this example, the current extraction electrode P was used as both the connection between the cells C and the collecting electrode.

The performance of this 3 series module is AM1 (100mW / c
Table 1 shows the results of measurement under m ² ) solar simulator light.

For comparison, the measurement results under the light of the AM1 solar simulator of the three series modules having the same mechanism in which the metal electrode layer, the amorphous silicon layer, and the transparent electrode layer are formed using the metal mask are shown.

The results in Table 1 show that there is no significant difference between the two and that a low resistance metal electrode-transparent conductive layer in series can be obtained by the manufacturing method of the present invention.

[Brief description of drawings]

FIG. 1 is a side sectional view of an example of a thin film solar cell of the present invention, and FIGS. 2 (A) and 2 (B) are side sectional views of the thin film solar cell at each step for explaining the present invention. FIG. 3 is a plan view showing a cell division pattern of the embodiment, FIG. 4 is a plan view showing a pattern of a current extraction electrode of the embodiment, and FIG. 5 is an explanatory view of a structure of the embodiment including a partial cross section. : Substrate ,: metal electrode layer: amorphous silicon layer ,: transparent electrode layer: groove, C: cell

Claims (4)

[Claims] 1. A current extracting electrode is connected from above to a lower electrode layer of a thin-film solar cell in which a lower electrode layer, a photovoltaic layer made of an amorphous silicon layer, and an upper electrode layer are sequentially laminated on an electrically insulating substrate. In this case, a region electrically insulated from the upper electrode layer is formed in a part of the photovoltaic layer, and a groove or a hole having a V-shaped cross section which reaches the lower electrode layer from the upper part by machining in the region. And a current extracting electrode made of a conductive resin electrically connected to the lower electrode layer by filling the groove or hole with the conductive resin, and providing the thin film solar cell. 2. The method for producing a thin film solar cell according to claim 1, wherein a groove or hole having a V-shaped cross section is formed by machining with a pointed processing member. 3. The method for manufacturing a thin-film solar cell according to claim 1, wherein a plurality of the grooves or holes are provided over the entire surface of the region. 4. The method for manufacturing a thin film solar cell according to claim 1, 2, or 3, wherein the current extraction electrode is provided by printing a conductive resin by a screen printing method.