太阳能电池正极浆料用超细银粉的制备

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

采用液相化学还原法,以聚乙二醇4000为分散剂,用抗坏血酸直接还原硝酸银溶液制备太阳能电池正极浆料用银粉。通过扫描电镜(SEM)、激光粒度分析仪和X射线衍射仪(XRD)等方法分析银粉的形貌、粒度及纯度,研究分散剂用量、抗坏血酸浓度、硝酸银浓度和溶液pH值等工艺条件对银粉粒度、物相结构及形貌的影响。结果表明,随着分散剂用量的增大,银粉颗粒粒度先减小后趋于稳定。在溶液pH值为4,抗坏血酸浓度和硝酸银浓度分别为2.0和0.5mol/L,聚乙二醇4000与硝酸银的质量比为0.10时,可以制得分散性好、纯度高、面心立方晶系和平均粒度为5.32μm的规则球形银粉。并将所得银粉调制成太阳能电池用浆料,通过丝网印刷在硅片上,使用四探针测试仪测得烧结膜的方阻为4.27mΩ/□,可满足太阳能电池的电性能要求。

Using ascorbic acid as reducing agent and poly （ethylene glycol） 4000 as dispersant, the ultra-fine sil- ver powder for solar cell grid electrode was prepared by chemical reduction. The morphology, size and purity of silver powder were analyzed by scanning electron microscopy （SEM）laser particle analyzer and X-ray diffraction （XRD）. The influences of reducing concentration of poly （ethylene glycol） 4000, silver nitrate, ascorbic acid, and pH value on the particle size and morphology were researched. The results show that the particle size of the silver powders decreases to be more stable with increasing dispersant concentration. The optimal reductive con- dition is： the pH value equals to 4, the concentration of ascorbic acid and silver nitrate is 2.0 and 0.5mol/L and m（PEG4000）/m（AgNOa） is 0. 10. Spherical silver powder with 5.32μm of particle size is good dispersion, high purity, face-centered cubic lattice. 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 4.27mΩ/□~, indicating the electrical property of the prepared silver is qualified for solar cell.