JPH0629562A - Solar battery and its manufacture - Google Patents

Abstract

PURPOSE:To form an antireflection film with low reflectance without lowering an open circuit voltage to improve an element efficiency by using a transparent body having many grooves as the antireflection film in stead of providing the surface of a silicon substrate with many grooves. CONSTITUTION:N<+>-diffused layer 2, passivation film 4 and antireflection film 5 are laminated on the surface of P-type polycrystalline silicon substrate 1, which is provided with a transparent resin layer 7 having many grooves in its surface. An electrode 6 is provided in the manner of passing through the layer 7 and BSF layer 3 is provided in the rear face of the electrode. Then, a liquid transparent epoxy resin is applied to the light-receiving face side of an element by the use of a spinner and solidified and deposited, and many minute grooves are formed on the surface of the resin by the use of a dicing device. Thus, it is possible to raise the open circuit voltage of the element and also to raise the efficiency of a solar battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell having a two-layer antireflection film and a method for manufacturing the same.

[0002]

2. Description of the Related Art To prevent the reflection of solar cells,
A texture structure is used. But the polycrystalline sun
The polycrystalline silicon substrate used for the battery is
Since the plane orientation is different, the texture texture used for single crystals
In etching, the entire substrate is exposed to a uniform low reflectance surface.
I can't come. Therefore, instead of the conventional texture surface treatment method,
, Using a dicing machine, etc.
Due to the low reflectance structure with many grooves formed on the entire surface, the characteristics
Has realized an improvement. Further reduce the reflection loss and improve the characteristics
Conventional TiO to improve₂Anti-reflection of single layer such as film
Instead of a film, MgF ₂/ TiO₂Such as a two-layer antireflection film
It is used.

FIG. 3 is a schematic sectional view of a conventional example. P
A large number of grooves are formed on the surface of the type polycrystalline silicon substrate 1, an N ⁺ diffusion layer 2 is formed on the surface, and a passivation film 4, a first antireflection film 5 made of TiO ₂ , for example, is further formed thereon. For example, a _second antireflection film 5-1 made of MgF ₂ and the like are stacked, and an electrode 6 that penetrates these layers and reaches the N + diffusion layer 2 is provided. BSF on the back
Layer 3 is provided. The back surface electrode is omitted.

[0004]

Forming a large number of grooves on the entire surface of the polycrystalline silicon substrate is effective in reducing the surface reflectance, but the open circuit voltage is lowered because the PN junction area is increased. There is a drawback that.

[0005]

In the solar cell of the present invention, a transparent body having a large number of grooves is used as the second antireflection film instead of providing a large number of grooves on the surface of the silicon substrate.

[0006]

According to the present invention, since no groove is formed in the silicon substrate itself, the PN junction area does not increase, the open circuit voltage of the polycrystalline solar cell is not lowered, and the antireflection film having a low reflectance is obtained. Can be formed, and the device efficiency can be improved.

[0007]

1 is a schematic sectional view of a solar cell according to the present invention. An N ⁺ diffusion layer 2, a passivation film 4, and a first antireflection film 5 are laminated on the surface of the P-type polycrystalline silicon substrate 1, and a large number of grooves 7-1, 7-1, ... Are provided on the surface thereof. A transparent resin layer 7 is provided. An electrode 6 is provided through these layers, and a BSF layer 3 is provided on the back surface. The back surface electrode is omitted.

The following is an example of the manufacturing method. First, FIG.
(A), the following form N ⁺ diffusion layer 2 on the surface of the P-type polycrystalline silicon substrate 1, N ⁺ diffusion layer in an acid atmosphere 2
Approximately 1 SiO ₂ film to be the passivation film 4 on the surface of
50 Å formed. After that, TiO ₂ was formed as the first layer antireflection film 5 by atmospheric pressure CVD. Next, B on the back
A P ⁺ layer to be the SF layer 3 was formed, a silver paste was fired and penetrated on the light-receiving surface side, and further solder dipping was performed to form the electrode 6.

Next, a liquid transparent epoxy resin is applied to the light receiving surface side of this element by using a spinner, and this is applied to
It was dried at 3 ° C. for 3 hours and solidified to deposit about 200 μm. As this resin, another resin may be used as long as it is a transparent resin having a refractive index of about 1.5, or another substance may be used. Then, a large number of fine grooves are formed on the resin surface by using a tying device.

FIG. 2B is a side view showing the method of forming the groove. For this processing, a disk-shaped blade 8 having diamond fine particles attached to the periphery of a circular metal plate was used and rotated at a high speed of about 30,000 rpm.
As for the shape of the blade, as shown in the figure, the blade 8 has a cutting edge angle θ ₂ of 70 ° so that the inclination angle θ ₁ of the groove is 55 °, and the depth d of the groove is Is about 70 μm
And If the inclination angle θ ₁ is 45 ° or more, the reflectance can be reduced.

Instead of forming the grooves after applying and drying the liquid transparent resin, a transparent body having a large number of grooves may be attached.

It can also be applied to a single crystal silicon substrate.

[0013]

The following Table 1 shows a comparison between the characteristics of the device according to the present invention and the characteristics of the conventional device.

[0014]

[Table 1] From this table, it is understood that the present invention makes it possible to fabricate a device having a low reflectance equivalent to that of the conventional structure and a higher open circuit voltage. As a result, the efficiency of the solar cell can be improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment according to the present invention.

FIG. 2A is a cross-sectional view of a solar cell before forming a second antireflection film, and FIG. 2B is a side view showing a method of forming a groove.

FIG. 3 is a schematic cross-sectional view of an example of a conventional solar cell.

[Explanation of symbols]

1 P-type polycrystalline silicon substrate 2 N ⁺ diffusion layer 3 BSF layer 4 passivation film 5 antireflection film 6 electrode 7 transparent resin layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tadashi Tonegawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Yoshihiko Takeda 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within the corporation

Claims (3)

[Claims] 1. A PN junction formed on the light receiving surface side of a substrate,
A first antireflection film formed on the surface of the PN junction;
And a transparent layer having a large number of grooves for reducing reflection provided on the surface of the antireflection film. 2. A first antireflection film is formed on the surface of a substrate on which a PN junction is formed, and a large number of grooves for reducing reflection are formed on a transparent layer formed on the surface and serving as a second antireflection film. A method of manufacturing a solar cell, comprising: 3. A first antireflection film is formed on a surface of a substrate having a PN junction, and a transparent body serving as a second antireflection film having a large number of grooves for reducing reflection is attached to the surface. A method for manufacturing a solar cell, comprising: