化学还原制备太阳能电池正极浆料用超细银粉

Preparation of ultra-fine silver powder utilized in paste for solar cell grid electrode

采用化学还原法制备太阳能电池正极浆料用超细银粉,通过扫描电镜(SEM)、激光粒度分析仪和能谱仪分析银粉的形貌、粒度及纯度,研究还原剂和分散剂的种类和用量,以及反应温度、溶液pH值等工艺条件对银粉粒度及形貌的影响。结果表明,采用水合肼作还原剂、明胶作分散剂时,可以得到分散性好、粒度约0.3μm的球状超细银粉;明胶的最佳加入量m(gelatin)为硝酸银质量m(AgNO3)的0.02倍,水合肼溶液和硝酸银溶液的最佳浓度分别为1.5mol/L和0.5mol/L;还原温度和溶液pH值对银粉粒度影响较大,当反应温度为20℃,硝酸银溶液pH值7.5时得到粒度均匀、形状规则的超细银粉。将该银粉制成浆料,印刷在硅片上,使用四探针测试仪测得烧结膜的方阻小于5mΩ/□,可满足太阳能电池的电性能要求。

The ultra-fine silver powder used in paste for solar cell grid electrode was prepared by chemical reduction. The morphology, size and purity of silver powder were analyzed by SEM, laser particle analyzer and EDAX. The effects of varied kinds and dosage of reducing agent and dispersant, reactive temperature and PH value on morphology and particle size were investigated. The results show that spherical silver powder with 0.3 μm of particle size can be prepared by using gelatin as dispersant and hydrazine hydrate as reductive agent. The best reductive condition is as follows： the content of gelatin re（gelatin） is 0.02 times of m（AgNO3）, the concentration of hydrazine hydrate and silver nitrate is 1.5 mol/L and 0.5 mol/L respectively, the temperature is 20℃ and pH value of AgNO3 is 7.5. The paste prepared with ready-made silver powder was printed on the silicon, and the square resistance of the sintered film tested by four point probe is less than 5mΩ/□, indicating the electrical property of the prepared silver is qualified for solar cell.