Effect of glass phase and temperature on contact resistance between Ag and Al electrodes

The contact resistance between rear Ag and Al electrodes is of crucial importance to the electrical performance of crystalline silicon solar cells. In this article, we reported the effect of glass phase in Ag paste and sintering temperature on the contact resistance between rear Ag and Al electrodes. The interface microstructure of Ag/Al contact and the surface morphology of sintered Ag electrodes were observed with a field-emission scanning electron microscope (FE-SEM), and the interaction between the glass frit and metal (Ag and Al) powder was deeply discussed. The results of our study showed that the thickening of Ag-Al alloy layer because of the sintering temperature rising to accelerate the inter-diffusion between Ag and Al electrodes would lead to an increase in the Ag/Al contact resistance. However, the increase of either glass phase content in Ag paste or sintering temperature could facilitate the formation of Ag precipitates in the inter-miscible zone between Ag and Al electrodes, which may resulted in a decrease in the Ag/Al contact resistance.