Improving front contacts of n-type solar cells

In this article we describe the work carried out in order to optimize n-type silicon solar cell front contacts by reducing the contact and line resistances. Both front and back contacts were created by screen-printing of a metal paste followed by the contact firing. After firing the front contacts were improved by electrolytic deposition of silver using a non-cyanide silver solution. In this work we used two different types of silicon wafers: electronic grade (EG-Si) and metallurgical grade (MG-Si). Two different solar cells processes were tested. The solar cells obtained where characterized before and after the plating step. For all the cells processed, the line resistance was reduced by over 85% after the silver deposition. After the contact improvement, EG-Si cells showed absolute efficiency improvements of the order of 3%, while MG-Si registered a minor efficiency improvement.