Hyperpure silver powder for solar cell conductive silver paste and preparing method of hyperpure silver powder

Abstract

The invention relates to a hyperpure silver powder for solar cell conductive silver paste and a preparing method of the hyperpure silver powder. The preparing method comprises the steps that a mixed reaction solution A of silver nitrate and a dispersing agent and an ascorbic acid mixed reducing solution B are prepared; the solution A and the solution B are preheated at a constant temperature in a water bath kettle, the solution A and the solution B are stirred in a magnetic mode and then mixed for conducting reduction reaction; aftertreatment and a plasma process are conducted on obtained silver powder to obtain the hyperpure silver powder which meets the demand of the solar cell conductive silver paste. A plasma technology is applied so that the prepared silver powder is high in purity, the purity is larger than or equal to 99.99%, the ohmic contact of the silver powder and a silicon substrate can be facilitated when the silver paste is sintered, and a dense membrane is formed. Under the premises that the purity is improved and the characteristics of the silver powder are not changed, the prepared silver powder is made to have the average grain diameter of 0.1-5 micrometers, grain diameter distribution is narrow, dispersity is good, tap density is larger than or equal to 4.5g / cm<3>, and the photoelectric converting efficiency of solar cells can be better improved. A plasma aftertreatment process is simple, and mass production is facilitated.

Description

technical field [0001] The invention relates to an ultrapure silver powder and a preparation method thereof, in particular to an ultrapure silver powder for solar cell conductive silver paste and a preparation method thereof, belonging to the technical field of electronic materials. Background technique [0002] With the depletion of global resources and the deterioration of the environment, the future solar photovoltaic technology and industry have strong competitiveness. Driven by the huge potential of the international photovoltaic market, the solar cell manufacturing industries of various countries are scrambling to invest huge sums of money and expand production in order to compete for a place. my country has become the largest producer and exporter of silicon solar cells. [0003] Silver powder has become an important material in the electrical and electronic industries due to its excellent electrical conductivity and application properties. It is the most widely used ...

AI Technical Summary

Problems solved by technology

But this also lays a hidden danger for the purification of silver powder. If the amount of dispersant is too small, it will not be enough to completely cover the silver powder, and it will not be able to disperse. If it is too much, it will bring difficulties to washing.

In order to obtain the higher silver powder of purity, most methods are to carry out a large number of times of water washing and alcohol washing to the silver powder, which not only causes waste, but also cannot obtain the higher silver powder of purity; In the method for preparing spherical ultrafine silver powder, in order to obtain silver powder with higher purity, the method of heat preservation and heat treatment at 350 ° C is used to remove impurities. Although relatively pure silver powder is obtained, the silver powder is very easy to agglomerate during high-temperature roasting. It can be seen that, The removal of dispersant is a technical problem faced in the preparation of highly dispersible and high-purity silver powder

Application number is 200610027065.0 in the preparation method of silver powder in the solar cell electrode printing paste disclosed by the Chinese patent, because the protective agent added in the preparation process of this method is too much, resulting in more coverings on the surface of the silver powder, affecting the conductive effect of the electrode, Moreover, the silver powder prepared by this method will pollute the silicon substrate, and the configured silver paste will have a large shrinkage rate when sintered at high temperature, and cannot achieve better ohmic contact with the semiconductor substrate, reducing the photoelectric conversion efficiency of the solar cell.