JPS58111379A - Thin-film solar cell - Google Patents

Abstract

PURPOSE:To improve photoelectric performance and yield by inserting a thin insulating layer between an Al electrode and amorphous Si. CONSTITUTION:An a-Si film 23 is formed, and monosilane and oxygen are flowed, and plasma-discharged. An amorphous Si layer with PIN structure is deposited by 6,000Angstrom , the degree of vacuum is increased, and the Si layer is plasma-discharged. A SiO2 film 24 with approximately 80Angstrom is formed onto the a-Si film through the process. Al Is attached by 0.5-1.0mum, and the Al electrode 25 is formed. According to such structure, the partial robbing of a-Si into Al and the diffusion of Al into a-Si as seen in the conventional devices can be prevented. Large difference is not recognized in the performance of the solar cell even when either of SiO, SiO2 or Si3N4 is used as an insulating film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses aluminum for electrodes in nine amorphous silicon solar cells, in which aluminum electrodes, amorphous silicon,
(hereinafter referred to as a-81).This invention relates to a thin film solar cell in which the yield and performance of the solar cell are improved by forming a thin insulating layer between the two.

In recent years, as an approach to lowering the cost of solar cells, a
Solar cells using -81 are attracting much attention.

As an example of the IIFIII structure of a conventional A-81 thin film solar cell, FIG. 1 shows a structure in which one electrode is covered with a transparent conductive film and the other electrode is covered with IIK metal. In the figure, 11 is a glass, 12 is a transparent conductive film, and it is usually Snow.

Indium tin oxide (indium tin oxide) is used.

First, Plil! from the transparent conductive film side with the 13-layer A-81 film.
.

It has a laminated structure of 1 layer and n layers. 14 is an aluminum electrode.

Light is emitted from the direction of the arrow, and the electrical output of the solar cell increases from the transparent electrode 12 and the metal contact 14.

As a manufacturing method, a normal plasma CVD method is generally used. "That is, the glass substrate 11 with the transparent conductive film 12 is placed in a vacuum container and heated to 250 to 300°C. - In this state, while flowing 5IH4, PHs, BAH gas as necessary, p , in, each a-81 film is formed.

After this, a sialuminium electrode 14 is applied by vacuum evaporation or sputtering IIIK. As the metal electrode, aluminum with a thick reflectance is used. This is to improve the efficiency of light utilization by reflecting the light that has passed through a-B1 into a-81 at the interface between aluminum and a-81. Aluminum also has the characteristics of being easy to vapor-deposit, and the resulting film has high electrical conductivity.

In FIG. 1, a case is described in which a transparent conductive film is used for one of the electrodes, but a structure in which both electrodes are made of metal and the electrode on which light is incident is made semitransparent is also possible. Also in this case, aluminum is used as the semitransparent electrode.

Because of this, Alζ is a material that is easy to use as an electrode, but on the other hand, it has major drawbacks.

The reason for this is that aluminum becomes eutectic with 81 at a low temperature of 1ift (several tens of degrees Celsius), and furthermore, it is easy to form a mineral in −1ε1. When atoms of aluminum fly with sufficient thermal energy during sputtering or vacuum evaporation, they easily (diffuse into a-Si. In some cases, they form eutectic with aluminum. , a-81 is locally removed, creating a pinhole.

Due to this phenomenon, the battery is prone to heavy rain.

The current increases or a seam-to-toe pattern occurs between the two electrodes due to pinholes, resulting in a decrease in photoelectric performance and a decrease in yield quality.

In addition, as a method to compensate for the drawbacks of aluminum electrodes having such a structure, there is a method of forming a thin film of a high melting point metal such as 9r, Mo, Dina, or Hf cape between the a-8i and the aluminum electrode. has also been proposed.

However, the adhesion between a-8i and these high-melting point metal thin films is poor, and due to subtle differences in manufacturing conditions, the film may peel off. This is a drawback.

The present invention eliminates such drawbacks, and its purpose is to: a) improve the photoelectric performance and yield quality of a thin-skinned solar cell while taking advantage of the good conductivity of the pH electrode; It is in. Another objective of the group is to improve the reliability of thin-mimetic solar cells.

FIG. 2 shows a cross-sectional structure of the present invention.

In the figure, 21 is glass, 22 is a transparent conductive film, and 23 is glass.
are a-St film and transparent conductive film, respectively.
It has a laminated structure of 1e n. 24 is thin absolute #I
50-10010810 richness in k layer, 810. Maku is 81
It is film number 1. Furthermore, there are 25 aluminum electrodes.

Light is emitted from the direction of arrow B.

In the manufacturing method of the present invention, the steps up to the step of laying a-8i Ill 2 S on the glass substrate @21 with the transparent conductive film 220 attached are the same as the conventional method. A thin insulating layer 24 is formed on the A-81 film 23, and its manufacturing method will be explained below using examples.

Example 1 (sio surprise case).

After forming the a-81 film 2S by the plasma OVD method, monosilicone y (81H4) and oxygen were subsequently flowed to cause plasma discharge. The manufacturing conditions depend on the O shape of the device, but we will discuss the case of a plasma OVD device having parallel plate type electrodes with a diameter of 20 mm.

The substrate temperature is 5 (10℃, high frequency output 40W, lit
Bass 101Elillk, 50OPPM PHi,
500PPM B! After the amorphous silicon layer with the pan structure is deposited for about 600 mL using H., the inside of the vacuum container is evacuated. Evacuate for about 5 minutes and when the vacuum level reaches -11X 10' Torr, turn off the H
! Pace's 10481H+ at 200cc/ml, 500 PPM Ox diluted with hydrogen at 50cc/mi
plasma discharge with a high frequency output of 40 W for 3 minutes. Through this process 11, an EliOt film of approximately 80λ is formed with a = si
formed on top.

Example 2 (Sia'M4) The a-81 film was formed on the edge under the same conditions as in Example 1, and the inside of the vacuum container was evacuated for about 5 minutes. Degree of vacuum is I x 10='ro
When reaching rr, 101Eli of Ht pace
H4 at 200cc/mln! Gas 10ac/mi
Through this process, approximately 801 81sH4 films are a-8i
formed on top.

Example s (In the case of 81o) After forming the a-81 film in the same manner as in Example 1, it was taken out of the vacuum container, and about 80° of the 810 film was formed by electron beam evaporation in a vacuum evaporator. 8i.

By any of the methods described in the above embodiments, a-
E! After forming an insulating film on the first layer, a full ξ+(L5 to IIIm) is applied by vacuum evaporation or sputtering.

With this structure, K
It is also possible that a-81 is locally removed into the aluminum.
Is it also to prevent aluminum from diffusing into -81?

Regarding insulating films, B10, 810 proverbs, 811M+
Even when noise deviation was used, there was no significant difference in solar cell performance.

When we investigated the photoelectric properties and yield of solar cells produced by the nine methods described in Examples 1 to 3, we found that they were all considerably improved compared to conventional ones.

For example, a solar cell in which an A-81 layer and an insulating layer were formed using the method described in Example 1 was compared with a solar cell having a conventional structure for about 100 devices.

In this case, the probability of producing a device with a photovoltaic force of 11 V or less is about 30 in the conventional case, but in the case of the device with the structure of the present invention, the probability of producing an element with a photovoltaic force of 11 V or less is about 8. The yield was greatly improved. Furthermore, when the photoelectric characteristics were measured using a 200 μm fluorescent lamp, the average values of the open circuit voltage and fill factor in the conventional book were αsav and ss*, respectively. However, in the structure of the present invention, the voltages were 0.61V and 611V, respectively, and the t conversion efficiency was improved accordingly.

As can be seen from the above description, the present invention is very effective in improving the photoelectric performance and yield of a-I111 thin film solar cells.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional a-Si thin film solar cell;
The figure is a sectional view of the invention. 21...Glass 22...Transparent conductive film 23...A-81 film 24...Thin insulating layer 25...Aluminum electrode or more Applicant: Hoseikosha Co., Ltd. Representative Patent Attorney: Mutsumi Mogami Figure 1) Figure 2

Claims (1)

[Claims] 1) An amorphous silicon thin film solar cell using at least 1iK aluminum, characterized in that a thin insulating layer is inserted between the aluminum electrode and the amorphous silicon. . 2) As an absolute layer, 810. 810tomi, 815M
1. A thin film solar cell according to claim 1, characterized in that at least one of + is used.