JP2774136B2 - Manufacturing method of amorphous silicon solar cell - Google Patents

Description

The present invention relates to a method for manufacturing an amorphous silicon solar cell in which a photovoltaic layer containing amorphous silicon as a main component and a protective layer are provided on a substrate.

More particularly, the present invention relates to a method for manufacturing an amorphous silicon solar cell in which a solar cell performance is improved by repairing a minute defect and stable and high efficiency is obtained.

[Prior art] Japanese Patent Laid-Open No. 60-1248 discloses an amorphous silicon solar cell.
It is known that the characteristics are improved by annealing in a high-temperature heating atmosphere or a high-temperature and high-humidity atmosphere as known in Japanese Patent Publication No. 82-82.

However, these treatments are very effective when the performance of the solar cell is originally low, but have little effect on the solar cell which already shows good characteristics.

Further, by W. Kruhler et al., Glass / SnO ₂ / p, i, n /
While applying a reverse bias electric field to the metal electrode structure solar cell,
It has been reported that annealing at 150 ° C or higher improves solar cell performance (Inter.PVSEC-
1 (1984) p. 127). This treatment has the effect of further improving good solar cell performance, but the effect was not so much recognized for the originally low solar cell performance. The cause of this performance improvement was attributed to the improvement in the doping effect of the n-layer.

However, these treatments are examples in which the solar cell is not in a practical form, that is, applied without a protective layer, and a defect occurs again through the step of providing a protective layer after the above treatment, The performance of the solar cell often decreases, and there is a problem that the production yield is reduced.

[Object of the Invention] The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a method of manufacturing an amorphous silicon solar cell capable of repairing a defect after laminating the protective layer and stably producing it at a high yield. It was done.

[Constitution and Operation of the Invention] That is, the present invention provides a photovoltaic device having a structure in which a pin-type photovoltaic layer containing amorphous silicon as a main component is sandwiched between transparent electrode layers on at least one of the substrates. In a method for manufacturing an amorphous silicon solar cell in which elements are laminated and a protective layer is laminated thereon, after the protective layer is laminated, 0.94 ×
A method for producing an amorphous silicon solar cell, comprising annealing at 80 ° C. or more while applying a reverse bias electric field of 10 ⁵ V / cm or more.

As a result of intensive studies to improve the above-mentioned conventional annealing method, the present invention described above shows that the polymer film used for the protective layer and the polymer resin used for the adhesion are not hindered by applying a reverse bias from the outside. It has been found that an amorphous silicon solar cell exhibiting good characteristics can be obtained with a good yield by annealing in a relatively low temperature atmosphere at a temperature lower than 80 ° C. at a temperature lower than 80 ° C.

 Hereinafter, the present invention will be described in detail.

The amorphous silicon solar cell to which the present invention can be applied is not particularly limited as long as it is made of a known pin-type photovoltaic layer containing amorphous silicon as a main component. The effect is remarkable in a device having a conductive or semiconductive oxide layer between the electrodes.

The following are specific examples of the amorphous silicon solar cell.

Examples of the substrate include glass, ceramics, a polymer film, or a sheet provided with a low-resistance metal layer or a transparent conductive film as an electrode, or a metal sheet. Among these, a polymer film that is low in cost and that can easily have a large area is preferable.

The photovoltaic layer provided on the substrate is mainly composed of a known amorphous silicon as a main component, particularly preferably a semiconductor film mainly composed of amorphous silicon deposited by a plasma CVD method. For deposition on polymer film substrates
The roll-to-roll method known in JP-A-56-150874, JP-A-61-187377 or JP-A-61-260681 is preferred in terms of productivity. As the polymer film, a heat-resistant film such as a polyethylene terephthalate (PET) film, a polyethylene naphthalate film, a polyimide, and a polyetheretherketone can be used.

The structure of the photovoltaic layer may be a three-layer structure of pins, and a single or tandem structure such as pin, pinpin, and pinpinpin is used.

As the p-layer on which the oxide layer to which the present invention is particularly preferably applied is laminated on the electrode side, either a known amorphous layer or a microcrystalline layer may be used, and carbon (C), germanium ( An alloy with Ge) may be used.

As the oxide layer formed on the electrode side surface of the p layer, a metal oxide layer is used, and a transparent and conductive layer such as indium oxide, titanium oxide, and chromium oxide, or a conductive layer thereof is preferably used. A multi-layer film is used, and its thickness only needs to be sufficient to form an interface layer with the p-layer.
Preferably, it should be at least 10 °. In addition, the loss due to the resistance in the oxide layer or the effective use of light is 100 mm.
The following is preferred.

As an electrode formed on the oxide layer on the p-layer,
A transparent electrode or a metal electrode is used, and which one is used is selected depending on the structure of the photovoltaic layer.

For example, in a structure in which a polymer film is used as a substrate, a metal electrode is used as a lower electrode layer, and a microcrystalline n layer, an i layer, and a microcrystalline p layer are deposited thereon, a transparent electrode is used as an upper electrode. As the lower metal electrode, a laminate of a metal layer such as Al, Au, Ag, Ni and the like having low resistance and extensibility, and a metal layer such as stainless steel, Cr, and Mo having good bonding characteristics with the silicon film is preferable. .

As the transparent electrode, a known good conductive oxide film such as indium oxide or tin oxide, or a laminate of a metal film is used.

When the p-layer is located on the upper electrode side, the above-mentioned ultra-thin oxide layer can be shared with a part of the transparent electrode, or may be separately provided between the p-layer and the transparent electrode. On the other hand, when the p-layer is located on the metal electrode side, this extremely thin oxide layer is provided at the interface between the metal electrode and the p-layer.

The solar cell to which the present invention is applied is one in which a protective layer for improving durability is provided on the surface of the photovoltaic element having the above structure facing the substrate. It is preferable to provide a polyester film or a fluororesin-based moisture-proof protective film as the protective layer. An organic polymer resin such as known ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), and ethylene ethyl acrylate (EEA) is used as an adhesive layer for bonding, and a protective layer is formed on the photovoltaic element surface by a lamination method. Provided above.

Incidentally, the application of the reverse bias electric field and the annealing of the present invention are for improving the performance of the solar cell and for repairing defects, and are performed after the completion of the module structure by bonding the protective layer. As the applied bias, the pin of the photovoltaic layer
As is clear from the embodiment, a reverse bias is selected and applied to the junction according to the structure and the film thickness so that an electric field of 0.94 × 10 ⁵ V / cm or more is generated in the structure. The magnitude of the reverse bias electric field is preferably 10 ⁵ V / cm or more in consideration of a film thickness variation due to a variation in manufacturing conditions and the like. This reverse bias electric field is applied through annealing, ie, heating and holding and subsequent cooling.

The annealing temperature is less than 150 ° C, which does not cause thermal damage to the substrate and the protective layer other than the adhesive layer, and is determined in consideration of the heating and holding time. Practically, a temperature of 80 ° C or more is preferable from the viewpoint of processing time and the like. .

[Effects of the Invention] The feature of the above-mentioned effects obtained by the present invention is p /
The junction at the interface between the i and p / oxide layers is improved, the fill factor in the solar cell characteristics is improved, and the open circuit voltage is improved by about 3%. In addition, even in solar cells with poor initial characteristics, the polymer resin layer is locally softened by the heat generated by current concentration at the reduced defect area by applying a reverse bias electric field, and the self-healing function that insulates the defective area is exhibited. By doing so, the performance can be improved. As described above, the performance of the solar cell having poor initial performance and the solar cell having excellent initial performance are improved, and as a result, the effect of improving the productivity of the solar cell is obtained.

 Hereinafter, embodiments of the present invention will be described.

Example 1, Comparative Example 1 FIG. 1 shows a laminated structure of a solar cell of this example. As the solar cell substrate (1), a 100 μm-thick polyester film capable of manufacturing a solar cell by a roll-to-roll method was used.

On this substrate (1), a metal electrode composed of two layers of Al / SS (stainless steel) was formed as a lower electrode (2), respectively.
It was deposited by a sputtering method to a thickness of 0.4 μm and a thickness of 50 mm.

The photovoltaic layer has a pin structure, and each type of amorphous silicon film is formed using a well-known plasma CVD method using a microcrystalline n-layer (3
c) The i-layer (3b) and the micro-crystallized p-layer (3a) were sequentially added to 200Å, 5000
Å, 100Å deposited. A tin-doped indium oxide (ITO) film was deposited to a thickness of 600 ° by sputtering as a transparent electrode (4) on the light incident side, also serving as an oxide layer to be joined to the p-layer.

Further, a comb-shaped silver electrode was provided as a take-out electrode (5) by a screen printing method in the same manner as a known electrode.

On the surface of the above photovoltaic element, a protective layer (7) of 100 μm was formed via an adhesive layer (6) made of EVA resin having a thickness of 100 μm.
A thick PET film was laminated and bonded to obtain a solar cell module of the example.

The solar cell performance of this solar cell module is AM = 1 (10
0mW / cm ² ) As a result of measurement under a solar simulator,
Conversion efficiency 8.8%, open circuit voltage (Voc) = 0.88V, short circuit current (Js
c) = 15.5 mA / cm ² , fill factor (FF) = 0.64.

Applying ⁵ V (reverse bias electric field: 0.94 × 10 ⁵ V / cm) between the lower electrode (2) and the extraction electrode (5) as a reverse bias electric field to the solar cell module while applying a reverse bias electric field in a 120 ° C. hot air dryer Heat treatment was performed for a time. It was taken out of the dryer and cooled naturally. The reverse bias electric field was continuously applied during cooling.

Table 1 shows the change of the solar cell characteristics together with the comparative example. In the comparative example, a solar cell module produced exactly as in Example 1 was subjected to only annealing without application of a reverse bias electric field under exactly the same conditions as in Example 1. The effect obtained by the present invention is characterized by an increase in FF, but an increase in Voc. 0.93 V was obtained by the treatment for 3 hours, and the conversion efficiency was improved to 10.2%.

Example 2 In the same manner as in the above-mentioned JP-A-61-187377 and JP-A-61-260681, a 100 cm ²
A publicly-known integrated solar cell module having a large area, divided into three cells and having three cells connected in series was prepared.
The protective layer and the adhesive layer were the same as in Example 1. As shown in Table 2, the initial values of this solar cell module were as low as 4.1%, Voc = 2.4V, FF = 0.43, and the performance of each cell stage was examined. This cell was particularly poor in performance and was expected to have some defects in the photovoltaic layer of this cell.

As a result of applying heat treatment at 120 ° C. for 3 hours while applying a reverse bias of 15 V to the solar cell module, both Voc and FF of cells in each stage were improved as shown in Table 2. In particular, the defect point was repaired in the first-stage cell, and almost the same performance was obtained as in the other-stage cells.

Thus, it is apparent that the present invention has the effect of improving the performance of the solar cell without damaging the adhesive layer, the protective layer, and the organic polymer resin layer of the substrate, and contributes to the improvement of the product yield. is there.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a laminated structure of an amorphous silicon solar cell module of an embodiment. (1) substrate, (2) lower electrode (3) photovoltaic layer, (4) upper electrode (5) extraction electrode, (6) adhesive layer (7) protective layer

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Claims (5)

(57) [Claims] A pi containing amorphous silicon as a main component is formed on a substrate.
An amorphous structure in which a photovoltaic element having a structure in which at least one of n-type photovoltaic layers is sandwiched between transparent electrode layers is laminated, and a protective layer is laminated thereon via an adhesive layer made of an organic polymer resin. In the method for manufacturing a porous silicon solar cell, after laminating the protective layer, annealing at a temperature of less than 150 ° C. and 80 ° C. or more is performed while applying a reverse bias electric field of 0.94 × 10 ⁵ V / cm or more between both electrodes. Of manufacturing an amorphous silicon solar cell. 2. The method of manufacturing an amorphous silicon solar cell according to claim 1, wherein the protective layer side of the amorphous silicon solar cell is a light incident surface. 3. The amorphous material according to claim 1, wherein the photovoltaic element has a semiconductive or conductive oxide layer between the p-layer of the photovoltaic layer and the electrode. Manufacturing method of silicon solar cell. 4. The semiconductor device according to claim 1, wherein the oxide layer is a semiconductive or conductive oxide layer of at least one metal selected from the group consisting of Sn, In, Ti, and Cr having a thickness of 10 ° or more and 100 ° or less. The method for producing an amorphous silicon solar cell according to any one of claims 1 to 3, comprising a single layer or a laminate. 5. The method for manufacturing an amorphous silicon solar cell according to claim 1, wherein said substrate is a flexible polymer film.