CN1983647A

CN1983647A - Method for passivating solar battery surface

Info

Publication number: CN1983647A
Application number: CNA2005101114566A
Authority: CN
Inventors: 汪乐
Original assignee: Shanghai Solar Energy Science and Technology Co Ltd
Current assignee: Shanghai Solar Energy Science and Technology Co Ltd
Priority date: 2005-12-13
Filing date: 2005-12-13
Publication date: 2007-06-20

Abstract

The invention is concerned with the method of the passive solar cell surface, the characteristic is: smears the tetraethoxysilane liquor that the consistency is 50% on the proliferated silicon slice with 15-28 centigrade, tetraethoxysilane thermal decomposes into SiO2 and hydrogen with 500-750 centigrade, SiO2 adheres to the silicon surface and enters the silicon surface by electrode agglomeration in order to get the passive effect. The invention can make the filling gene of the polycrystalline silicon solar cell to increase over 10% without change the existing production processing of the solar cell at the condition of not use the PECVD equipment method.

Description

Method for passivating surface of solar cell

Technical Field

The invention relates to a method for passivating the surface of a solar cell.

Background

A solar cell is a semiconductor device that can directly convert solar light energy into electric energy. The solar photovoltaic power generation device has the characteristics of no need of water, oil, steam and fuel during working and capability of generating power only by light, can be called as a modern clean and pollution-free renewable energy source, is simple to install and maintain, has long service life, can realize unattended operation, is favored by people, and is outstanding as a new energy source. In recent years, solar energy is applied more and more globally, and particularly in the field of communication, a solar power system is gradually replacing some traditional power devices and is applied more and more generally.

The silicon solar cell has a large number of surface state defects, which affect the performance of the cell. The batteries with high photoelectric conversion efficiency (laboratory manufacturing and space batteries) are added with preparation S_iO₂Or H₂The passivation process covers the surface of the solar cell with a passivation layer, and the passivation layer has the following functions: (1) passivate the front surface of the solar cell, reduce the interface state density of the interface of the substrate and the passivation layer,reducing the recombination velocity of photogenerated carriers at the interface; (2) reducing the reflection of light.

The passivation layer on the surface of the solar cell in the prior art adopts Si₃N₄、SiO₂、TiO₂Or Ta₂O₃And the like, single or multi-layer dielectric films. Chinese patent CN1085013A discloses a MIS/IL bifacial solar cell made of semiconductor material and covered with a passivation layer on its surface, but does not disclose the deposition process of the passivation layer. Chinese patent CN1564311A discloses a composite passivation process for a silicon semiconductor mesa device, which utilizes a dc glow discharge method to deposit an oxygen-doped semi-insulating polysilicon film on a terminal mesa of the semiconductor device, and then coats polyimide on the oxygen-doped semi-insulating polysilicon film to achieve the purpose of passivating the semiconductor mesa device. Chinese patent CN1023953C discloses a passivation process for semiconductor mesa devices, which comprises washing the etched mesa device, and immediately adding pre-prepared HF, HNO₃，HAc，H₂In O solution, making itFirstly, a layer of dyeing film is formed, then after the protective glue is removed, the stable treatment is implemented, then the obtained product is placed in a deposition furnace, a layer of silicon nitride is deposited, finally a layer of silicon paint is coated, so that the dyeing film-Si is formed on the table-board₃N₄-a multilayer protective layer of silicone lacquer.

The Chinese patent CN1564311A utilizes a direct current glow discharge method to carry out a composite passivation process, and the method is not suitable for the continuous production of civil large-area solar cells. The purpose of the passivation of the chinese patent CN1023953C is to protect the mesa of the semiconductor device from the environment, especially when the device is used at high temperature (above 90 ℃), the stability and reliability of the device are improved, and unlike the passivation of the solar cell, the surface of the solar cell is less likely to be coated with a layer of silicon paint to affect the absorption of sunlight.

At present, the solar cell industry at home and abroad generally adopts T_iO_xAnd S_iN_xAs an antireflection film on the surface of the battery, wherein T_iO_xThe film only functions as an antireflection film, and S is prepared by PECVD_iN_xAt the time of film formation, S_iH₄And NH₄Plasma and silicon surface generation S_iN_xAnd hydrogen gas. And passivating the defects of the surface state and the interface state of the crystal by using hydrogen to reduce the recombination speed of the surface state and the interface state. But PECVD equipment suitable for continuous production of large-area civil silicon solar cells cannot be manufactured at home, and the price of imported PECVD equipment is about ten million RMB. Dry and wet preparation method for space battery_iO₂The passivation solution can play a good role in passivation, but is suitable for small-area solar cells, is not suitable for continuous production of large-area solar cells, and is not adopted.

Disclosure of Invention

Aiming at the defects that the surface passivation process of the solar cell is complex, the method is suitable for a small-area solar cell and is not suitable for the continuous production of a large-area solar cell in the prior art, the invention provides the method for passivating the surface of the solar cell, which has a simple process and is suitable for the continuous production of the large-area solar cell.

The method for passivating surface of solar cell is characterized by that it uses tetraethoxysilane solution whose concentration is 50% to coat diffused silicon chip under the condition of 15-28 deg.C, and under the condition of heating condition of 500-750 deg.C the tetraethoxysilane can be thermally decomposed to produce S_iO₂And hydrogen, S_iO₂Adhered to the silicon surface and enters the silicon surface when being sintered by the electrode to play a role in passivation.

The chemical principle of the method for passivating the surface of the solar cell is mainly thermal decomposition of tetraethoxysilane. The thermal decomposition equation of tetraethoxysilane is:

compared with the prior art, the invention provides a simple and practical passivation process which does not change the existing continuous production procedure of thecivil solar cell, does not increase special equipment and has low cost. Under the condition of not adopting a PECVD (plasma enhanced chemical vapor deposition) device, the process can increase the filling factor of the polycrystalline silicon solar cell by more than ten percent.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1

A preferred embodiment of the present invention provides a method for passivating a surface of a solar cell, comprising the steps of:

(1) preparing tetraethoxysilane solution with the concentration of 50 percent;

(2) coating the tetraethoxysilane solution prepared in the step (1) on the diffused silicon wafer at 21 ℃;

(3) placing the diffused silicon wafer coated with the tetraethoxysilane solution obtained in the step (2) into a drying furnace heated to about 125 ℃ for drying;

(4) and (4) placing the silicon wafer dried in the step (3) into a sintering furnace capable of rapidly heating and rapidly cooling, and treating at the high temperature of about 725 ℃ for 35 seconds.

Through detection, the filling factor of the polycrystalline silicon solar cell passivated by the method is increased by 12.3% compared with the polycrystalline silicon solar cell passivated without any passivation treatment.

Example 2

In this example, the temperature of the drying furnace in the step (3) was 140 ℃, the temperature of the sintering furnace in the step (4) was 705 ℃, and the treatment time was 1 minute, as in example 1.

According to detection, the filling factor of the solar cell passivated by the method is increased by 11.1% compared with the solar cell passivated without any passivation treatment.

Example 3

In this example, the temperature of the drying furnace in the step (3) was 110 ℃, the temperature of the sintering furnace in the step (4) was 740 ℃, and the treatment time was 11 seconds, as in example 1.

Through detection, compared with polycrystalline silicon which is not passivated (the other conditions are the same as the embodiment), the filling factor of the solar cell passivated by the embodiment is increased by 10.9%.

Claims

1. A process for passivating the surface of solar cell includes such steps as coating the solution of tetraethoxysilane (50%) on diffused silicon wafer at 15-28 deg.C, and thermal decomposing tetraethoxysilane to generate S under 500-750 deg.C_iO₂And hydrogen, S_iO₂Adhere to the silicon surface.

2. The method as claimed in claim 1, wherein the diffused silicon wafer coated with the tetraethoxysilane solution is dried in a drying furnace at 100-150 ℃, and then heated at 500-750 ℃.

3. The method of passivating a surface of a solar cell according to claim 1, wherein the heating at 500 ℃ to 750 ℃ is performed in a rapid-temperature-rise, rapid-temperature-fall sintering furnace.

4. The method of passivating a surface of a solar cell according to claim 1, wherein the diffused silicon wafer coated with the tetraethoxysilane solution is treated under heating at 500 ℃ to 750 ℃ for 10 to 60 seconds.