Low-resistance high-efficiency lead-free back silver pulp for amorphous silicon solar battery

Abstract

The invention relates to low-resistance high-efficiency lead-free back silver pulp for an amorphous silicon solar battery. The lead-free back silver pulp comprises the following ingredients in percentage by mass: 35 to 65 percent of silver powder, 1 to 6.5 percent of inorganic bonding agents and 30 to 60 percent of organic bonding agents, wherein the silver powder is microcrystal silver powder with the average grain diameter being 0.2 to 3 micrometers, the lead-free glass powder is formed by combining A glass powder with the softening point being 550 to 750 DEG C and B glass powder with the softening point being 400 to 540 DEG C, the A glass powder is preferably the glass powder with the softening point being 600 to 700 DEG C, and the B glass powder is preferably the glass powder with the softening point being 425 to 500 DEG C. A battery cell manufactured by the back sliver pulp provided by the invention has the advantages that a back silver electrode and an aluminum electrode metal fusion layer have no crack gap, the contact resistance of a silver aluminum electrode is small, and the conversion efficiency of the battery cell is high.

Description

technical field [0001] The invention relates to the technical field of solar energy, in particular to a lead-free back silver paste for crystalline silicon solar cells. Background technique [0002] A solar cell is a semiconductor device that converts solar energy into electrical energy. Under the condition of light, a photogenerated current is generated inside the solar cell, and the electrical energy is output through the electrodes. In order to maximize the output of photoelectric energy, electrode fabrication becomes an important link. The electrodes of crystalline silicon solar cells include positive silver electrodes, back silver electrodes, and aluminum electrodes. The back silver electrode of crystalline silicon solar cells mainly plays the role of being solderable and forming a conductive path with the aluminum electrode. The conductivity of the back silver electrode and the conductive contact performance with the aluminum electrode also directly affect the convers...

AI Technical Summary

Problems solved by technology

[0003] At present, the mainstream back silver paste in the market has the following deficiencies: After the back silver paste is printed and sintered, cracks appear on the surface and inside of the overlapping parts of the back silver electrode and the aluminum electrode, which affects the conduction between the silver and aluminum electrodes, resulting in battery failure. The higher the series resistance, the lower the conversion efficiency of the solar cell

Some researchers found that by adding inorganic oxides, such as nano-SiO 2 Such low expansion coefficient materials can reduce the expansion coefficient of aluminum paste and prevent cracks due to sintering shrinkage. However, in practical applications, it is found that the above low expansion coefficient materials will greatly reduce the adhesion of aluminum electrodes, seriously affecting the appearance of cells and lamination reliability.

Add nano-SiO to the back silver paste 2 Such inorganic oxides can also reduce the occurrence of cracks after sintering, but have a serious impact on the adhesion of the back silver electrode

The U.S. patent shows that by controlling the particle size of the silver powder at 5.0-11.0 μm, the sintering degree of the back silver paste is reduced to reduce cracks. However, due to the large particle size of the silver powder, the sintering temperature of the back silver paste is high, resulting in the formation of an alloy or co-alloy with the aluminum paste. The ability of the crystal is weak, and the conductive connection between the back silver electrode and the aluminum electrode is weakened, which causes the series resistance of the cell to increase and reduces the photoelectric conversion efficiency of the cell.

Images