SEM microstructure, composition, property correlation-ships in aluminum conductors

Al paste applied on the back surface of silicon solar cells, plays a critical role in the overall performance of solar cells. The quality of the BSF (back surface field) impacts the Voc values and thus the efficiency obtained in the solar cell [1-3]. A Taguchi screening experiment was conducted to study effects of processing and formulation on paste viscosity, uniformity of BSF, bowing and dusting. The thickness and uniformity of BSF (back surface field) formed was found to be a direct function of various factors including type of Al powder, chemistry of glass, other oxide and metal additives as well as the firing conditions used. The electrical performance, bowing and dusting are correlated with microstructure and paste compositions, and are discussed below.