Method for producing spherical aluminium powder for p-type aluminum-doped back electrodes of crystalline silicon solar cells

Abstract

The invention discloses a method for producing spherical aluminium powder, and the aluminium powder is used for aluminum-doped back electrodes (with the characteristics of p-type semiconductors) of crystalline silicon solar cells such as mono-crystalline silicon solar cells, polycrystalline silicon solar cells and the like. The contents of the invention comprise production process and equipment composition as well as the contents of elements including aluminium, silicon, iron and gallium and a method for blending the elements; the method comprises the following steps: preparing spherical aluminium powder blanketed with high-purity nitrogen; adding ozone into the nitrogen to mix with the aluminium powder, and then carrying out ultraviolet irradiation on the obtained mixture so as to form an amorphous activated aluminium oxide film on the surface of the spherical aluminium powder at low temperature; and carrying out ultraviolet irradiation on the ozone in the nitrogen so as to decomposethe ozone into oxygen, and then carrying out harmless emission. The invention overcomes the defect that the existing spherical aluminium powder for aluminum-doped back electrodes of the crystalline silicon solar cells is prepared by using remelting aluminium ingots as raw materials; the metal gallium content of the spherical aluminium powder is increased to reach a certain range, which improves the characteristics of the P-type semiconductors; and an amorphous activated aluminium oxide film is formed on the surface of the spherical aluminium powder at low temperature, which can reduce the resistance of the electrode, and increase the adhesive power of silicon and aluminium.

Description

technical field [0001] The invention relates to a method for producing spherical aluminum powder used for aluminum electrodes on the back of monocrystalline silicon and polycrystalline silicon solar cells. The spherical aluminum powder is specially used for sintering to form the back of crystalline silicon solar cells with P-type semiconductor characteristics. The raw material of aluminum electrode is metal powder material. Background technique [0002] Spherical aluminum powder is used on the aluminum back electrode of crystalline silicon solar cells. Spherical aluminum powder with a certain particle size of less than 13 microns is mixed with a solvent to make a slurry, which is printed on polycrystalline silicon and monocrystalline silicon wafers by screen printing. Then sinter at a temperature of 680-920° to form the aluminum back electrode of the solar cell on the back of the silicon wafer. The surface of the spherical aluminum powder needs a certain amount of alumina f...

AI Technical Summary

Problems solved by technology

The high silicon content in the spherical aluminum powder forms a coarse crystal structure during the recrystallization of the aluminum liquid, which makes the aluminum-silicon adhesion poor, and leads to the combination of the aluminum liquid and the silicon wafer to form an aluminum-silicon alloy substance, which increases the resistance and reduces the photoelectric conversion rate. Semiconductor properties that affect the P-type doping of aluminum to silicon

(2) The trace element "gallium" that produces semiconductor characteristics contained in the produced spherical aluminum powder is very small, which affects the semiconductor characteristics of P-type doping

(3) The properties of the aluminum oxide film on the surface of the produced spherical aluminum powder are unstable

Therefore, the existing spherical aluminum powder production methods cannot stably produce special spherical aluminum powder suitable for the application of aluminum back electrodes of crystalline silicon solar cells and having good P-type doping function

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