Preparation And Electrical Properties Of Nano-modified Lead-free Conductive Silver Paste

The preparation and electrical properties of nano-modified lead-free conductive silver paste were investigated in this work. Micron and nano silver were used as the conductive functionality. Through liquid phase reduction method, using silver nitrate as oxidant, sodium hypophosphite and dilute sulfuric acid as reducing agents, sodium hexametaphoshpate as dispersant, polyvinylpyrrolidone as protective agent, ammonia solution as the regulator of pH value, we prepared the nano-silver particles with the size of20-70nm and also concluded that the form of silver microcrystalline was the combined effect of Ag+and glass frits; Bi2O3-B2O3-SiO2lead-free glass phase was used as inorganic glass binder, also Al2O3, MnO2, MgO, CaO and Ta2O5as the functional materials, we investigated the important role of inorganic phase as flux and binder during the sintering process; a-Terpineol,2-Ethoxyethyl acetate and Ethyl cellulose were used as the organic carrier, we investigated their important effect for viscosity and printing performance of conductive paste during the sintering process; printed the paste through the manual screen printing, we ues the method of low-temperature drying and high-temperature sintering to prepared the silver electrode in specific atmosphere. The resistivity of silver electrode was measured by four-point probe, the morphologies were observed by SEM and TEM, and the photovoltaic properties of solar cells were measured by Keithley2400under an illumination of AM1.5G. We investigated the influence of total silver content, content and size of nano-silver and sintering temperature on each properties. The comprehensive performance of silver electrode sintered from the paste containing70micron-silver and5%nano-silver with the size of30nm was the best.