Conductive silver paste and preparation method thereof

Abstract

The invention provides a conductive silver paste used for a solar cell device. The silver paste includes a silver powder, an organic carrier, and a glass powder, wherein the glass powder includes TeO2 with a weight percentage of 20-75%, PbO with a weight percentage of 20-50% and La2O3 with a weight percentage of 1-40%. The invention also provides a preparation method of the conductive silver paste. Through adoption of the conductive silver paste and the preparation method thereof, excellent ohmic contact of a positive silver grid line and a silicon wafer can be realized and particularly, better ohmic contact is formed on high sheet resistance and at the same time, the content of lead compounds in the conductive silver paste is significantly low so that a convention that traditional silver pastes are mostly high-lead glass powders is changed greatly and use of toxic compounds is reduced and pollution of environment is reduced; and at the same time, addition of the La element improves significantly the use reliability of a silicon-based solar cell.

Description

technical field [0001] The invention relates to the field of solar devices, in particular to front-side silver paste for silicon-based solar cells and its preparation. Background technique [0002] With the shortage of fossil energy and people's concern about carbon dioxide emissions, solar power generation technology has been developed by leaps and bounds. As the main body of solar power generation technology, crystalline silicon solar cell technology has always attracted people's attention, and its photoelectric conversion efficiency has been continuously improved. [0003] The quality of solar cells depends on the carrier concentration, distribution and mobility in the crystalline silicon material used, and is also affected by the performance of the positive and negative electrodes of the battery. The front electrode directly affects the series resistance, shunt resistance, fill factor and photoelectric conversion efficiency, so the quality of the silver paste on the fro...

AI Technical Summary

Problems solved by technology

[0008] In the previous technology, there was a patent for using tellurate glass powder to prepare front silver paste for solar cells. However, the glass transition point of tellurate glass is relatively low, generally at 250-300 degrees Celsius, while front silver paste is usually The required glass softening point should be 350-380 degrees Celsius, in order to cooperate with the high temperature sintering process of the grid wire

At the same time, the stability of tellurate glass is poor, either no crystallization, or a large amount of crystallization

A small amount of crystallization is beneficial to the sintering strength of the grid line and the silicon substrate, but a large area of ​​crystallization will increase the recombination of carriers at the grid line, reduce the open circuit voltage of silicon-based solar cells, and thereby reduce the photoelectric conversion efficiency of the cell, so , the silver paste prepared by tellurite glass powder either has high efficiency and low welding tension, or high welding tension and low efficiency