JPH02164077A - amorphous silicon solar cell - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an amorphous silicon solar cell with high photoelectric conversion efficiency.

[Conventional technology]

Conventional high-efficiency amorphous silicon solar cells were published in Japanese Patent Application Publication No. 6
As described in Japanese Patent No. 1-251177, a thick transparent electrode (tin oxide) with large irregularities is formed on a glass substrate, and p-type a-S i C:H, i-type a- 8i
:H, n-type μc (microcrystal)-3i:H, In the structure where metal electrodes are sequentially formed, the incident light is trapped between the uneven transparent electrode and the metal electrode, effectively blocking the light. It has the feature of being able to be converted into generated carriers.

On the other hand, Japanese Patent Application Laid-Open No. 57-49275 discloses a method in which, instead of making the transparent electrode uneven, unevenness is formed on the surface of a glass substrate and used for a solar cell substrate.

[Problem to be solved by the invention]

In the former conventional technology above, the transparent electrode is 8 because of the uneven surface.
It is formed to be as thick as 000 to 9000 mm, and impurities are added to lower the resistance. Therefore, there was a problem that the light transmittance (75 to 85%) of the transparent electrode was low.

Furthermore, since the unevenness of the transparent electrode is caused by a chemical reaction during the formation of the transparent electrode, controllability is poor, and the shape of the unevenness is irregular, resulting in poor reproducibility.

Furthermore, both of the above conventional techniques have a problem in that a reaction occurs between the transparent electrode and the amorphous silicon film, and this reaction limits the efficiency of the amorphous silicon solar cell. In particular, in the latter conventional technique, ITO is used as the transparent electrode.
(Indium tin oxide) was used, so the problem of deterioration of the characteristics of the solar cell due to the above reaction was serious.

Therefore, an object of the present invention is to solve the above problems.

The purpose of the present invention is to provide an amorphous silicon solar cell with high photoelectric conversion efficiency.

[Means to solve the problem]

In order to achieve the above objective, a textured glass substrate and a patterned metal electrode share the roles of the textured shape for effective use of light and the role of a current extraction electrode, which the textured transparent electrode had in conventional solar cells. It is.

In order to achieve the above object, a patterned metal electrode is formed on the uneven surface of a glass substrate (abbreviated as an uneven glass substrate) having an uneven surface, and a pin type amorphous silicon solar cell is formed on this.

Furthermore, in order to achieve the above object, an insulating light-transmitting film with a refractive index of 1.7 to 2.5, a patterned metal electrode, p-type mechanocrystalline silicon, and i- and n-type amorphous silicon materials are coated on the uneven glass substrate. The layers are sequentially formed to form an amorphous silicon solar cell.

In addition, in order to achieve the above object, a patterned metal electrode and a transparent electrode with a film thickness of 4000 Å or less or a sheet resistance of 30Ω/□ or more are formed on the uneven glass substrate, and
An amorphous silicon solar cell was obtained by sequentially forming layers of pH 11 n-type amorphous silicon material.

[Effect]

The unevenness of the surface of the glass substrate can be achieved by machining, embossing, photoresist patterning, chemical etching, etc., so it is much more controllable and homogeneous than the unevenness of transparent electrodes. Therefore, the uneven glass substrate is suitable for increasing the area of solar cells. Furthermore, by using only a patterned metal electrode or a combination with a high-resistance thin-film transparent electrode for the light incident side electrode, light absorption loss and reaction with amorphous silicon can be reduced, and the efficiency of amorphous silicon solar cells can be increased. realizable. The uneven transparent electrode for conventional solar cells has a film thickness of 8,000 to 90
00 people, sheet resistance 5-15Ω/□, light transmittance 75-8
It was 5% 5n02.

There is a relationship between sheet resistance and light transmittance as shown in FIG. 5, and by setting the sheet resistance to 30Ω/□ or more, the light transmittance can be made to be 90% or more.

At this time, the film thickness is 4000 Å or less. When only patterned metal electrodes are used, the refractive index of the glass substrate is 1.4.
5 and the refractive index of the amorphous silicon material 3.5 to 4.
Since the difference between 0 and 0 is large, a light transmitting film with a refractive index of around 2.1, that is, 1.7 to 2.5, is formed between the two to improve optical matching and reduce interface reflection loss of incident light. Can be done.

In addition, by microcrystallizing the amorphous silicon material on the side of the patterned metal electrode or the high-resistance thin-film transparent electrode, the series resistance of the solar cell can be lowered, reducing the deterioration of characteristics due to series resistance under sunlight irradiation. It is possible to achieve high efficiency.

〔Example〕

The present invention will be explained in detail below.

Example 1゜ This will be explained using FIGS. 1 and 2.

A chevron-shaped groove was formed on one surface of the glass substrate 1 using a mechanical grinding method. Here, the distance between the peaks was 50 μm, and the height of the peaks was 40 μm. A patterned Cr electrode 2 is formed on the uneven surface.
was formed. An example of this electrode pattern is shown in FIG.

Next, as the 5p type half layer 3, a 150-layer thick microcrystalline SiC:H film containing B as a dopant was formed by microwave plasma CVD. Subsequently, 500 amorphous Si:H was used as the n-type semiconductor layer 4, and 3 containing P as a dopant was further added as the n-type semiconductor N5.
00 microcrystalline Si:H was formed by RF plasma CVD method. Thereafter, AQ was deposited as a back electrode 6 to obtain a solar cell. The short-circuit current density of this solar cell was 5% higher than that of a conventional solar cell in which p-type amorphous SiC:H was formed on a concavo-convex transparent electrode, and the open-circuit voltage was low because a microcrystalline layer was used as the p-type semiconductor layer. It showed a 5% larger value. In addition, in a solar cell in which p-type mechanocrystalline SiC:H is directly formed on a concave-convex transparent electrode, the photoelectric conversion efficiency is a very poor value of 174 or less than that of the conventional solar cell mentioned above due to reactions between the transparent electrode and the p-type layer. According to the present example as described above, the short circuit current density and the open circuit voltage can be increased, and therefore a highly efficient solar cell can be obtained.

Example 2゜ This will be explained using FIG.

The solar cell shown in FIG. 3 has the same structure as Example 1, except that a 600-layer thick TiO film is formed as a light-transmitting film 31 between the glass substrate 1 and the Cr1t electrode 2 of Example 1 by thermal CVD. It was created. In the solar cell, glass, Tide
The refractive index of P-type mechanical crystal SiC:H is 1.45 and 2, respectively.
．． 2,3.6, the provision of Ti○ improves the matching of the refractive index and reduces the interface reflection loss of light, resulting in the short circuit current density of the solar cell being 10% compared to the above conventional type.
It showed a high value.

Note that as the light transmitting film 31, in addition to the above-mentioned TiO, Si
, Ta2O, , MgO, a-Si, N4. a-8in,
, Cff, 5, etc. may be used.

Example 3゜The SiO in Example 2 was changed to a 5no2 film with a film thickness of 3000 mm and a sheet resistance of 150Ω/□, and the p-type mechanical crystalline SiC:H was changed to p-type amorphous SiC:H, and the rest was the same as in Example 2. A battery with the same structure as 1'J) was created. High sea 1
Due to the increased light transmittance due to the use of the thin film SnO2, the short circuit current density of the solar cell is 10% lower than that of the conventional type.
% or more.

Example 4゜ This will be explained using FIG.

When connecting the solar cell elements of Examples 1 to 4 above in series,
The surface of the element portion of the glass substrate 1 was made uneven, and the connection portion between the elements remained flat. A solar cell element having the same structure as in Example 2 was formed on the glass substrate. That is, Ti031. patterned Cr electrode 2, p-type semiconductor layer 3, n-type semiconductor layer 4,
After forming n-type semiconductor layers 5 in sequence, these semiconductor layers are patterned using a laser beam, and AQ electrodes 6 are formed on the semiconductor layers.
was deposited using a mask. By keeping the substrate surface of the inter-element connection portion flat, patterning of the semiconductor layer has become very easy.

〔Effect of the invention〕

According to the present invention, it is possible to effectively utilize incident light by using a textured glass substrate, and by using a patterned metal electrode alone or in combination with a high-resistance transparent electrode instead of a low-resistance transparent electrode, an amorphous silicon-based material can be used. Since the reaction with the amorphous solar cell can be reduced, it is possible to obtain an amorphous solar cell with a high short-circuit current density and therefore a high efficiency.

Further, by combining a patterned metal electrode and a light-transmitting film having a refractive index of 1.7 to 2.5, a solar cell with even higher short-circuit current density can be obtained.

Furthermore, by using microcrystalline silicon or microcrystalline silicon alloy as the p-type or n-type semiconductor layer on the light incident side,
High open circuit voltage can be obtained. In combination with the above-mentioned high short circuit current density, it is possible to achieve even higher efficiency.

Furthermore, when the present invention is applied to an integrated amorphous solar cell, the glass surface of the inter-element junction may be kept flat or smooth.

The production of integrated solar cells can be facilitated.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, and FIG. 2 is a Cr electrode pattern diagram of the first embodiment of the present invention. FIG. 3 is a vertical cross-sectional view showing a second embodiment of the present invention, and FIG. 4 is a vertical cross-sectional view showing a fourth embodiment of the present invention. FIG. 5 is a diagram showing the relationship between sheet resistance and light transmittance of a tin oxide transparent electrode. 1... Glass substrate, 2... Patterned metal electrode, 3
... n-type semiconductor layer, 4 ... i-type semiconductor layer, 5 ...
n-type semiconductor layer, 6... metal electrode, 31... light transmitting film. 7th eye 3rd eye 2nd eye circle 4th eye 3: P quantum 4-weight layer Z: Metal 9.8! n) breath pit (va)

Claims (1)

[Claims] 1. Amorphous silicon consisting of a stack of amorphous silicon materials such as amorphous silicon, amorphous silicon alloy, microcrystalline silicon, microcrystalline silicon alloy, etc. formed on the uneven surface of a glass substrate having an uneven surface. An amorphous silicon solar cell comprising a patterned metal electrode partially formed between a glass substrate and an amorphous silicon material. 2. In claim 1, at least a portion of either or both between the glass substrate and the patterned metal electrode, or between the patterned metal electrode and the amorphous silicon-based material, has a refractive index of 1.7 to 2. An amorphous silicon solar cell characterized by forming a light transmitting film of .5. 3. In claim 1, a transparent electrode with a sheet resistance of 30Ω/□ or more is provided between the glass substrate and the patterned metal electrode, or between the patterned metal and the amorphous silicon material, or at least in a portion of both. An amorphous silicon solar cell characterized by the formation of an amorphous silicon solar cell. 4. In claims 1 to 3, the amorphous silicon-based material of p-type or n-type closest to the patterned metal electrode is microcrystalline silicon or microcrystalline silicon alloy. silicon solar cell. 5. In an integrated amorphous silicon solar cell formed on the uneven surface of a glass substrate having an uneven surface, the amorphous silicon solar cell is characterized in that the unevenness of the glass substrate surface is different between the element forming part and the inter-element junction part. battery. 6. The amorphous silicon solar cell according to claim 5, characterized in that the surface irregularities of the glass substrate in the inter-element bonding area are generally gentler than in the element forming area.