Cost-Effective Front Contact Metalization by Copper Paste for Screen-Printed Crystalline Silicon Solar Cells

Ag front metallization cost shares about 30% of the total cost of cell fabrication process. Several new front metallization processes have been recently introduced to reduce the use of silver as an alternative to it. Cu electro-platting is a promising technique for metallization. However, the fast diffusivity of Cu in silicon causes lifetime degradation. In order to avoid this degradation of lifetime, additional barrier layer with less diffusivity metals such as Ti or Ni need to be used beneath the Cu metallization grid. Because the Ag busbar consumes about 60% of the total silver in the standard front H pattern metallization, replacing the Ag busbar with Cu busbar will provide the best solution to reduce the cost and to avoid deterioration of the bulk quality by eliminating direct contact between the Cu busbar and the silicon. In this work, low melting point alloy (LMPA) Cu paste was used for the replacement of Ag front busbar of conventional crystalline silicon solar cells and were compared to the cells with Ag contact.