Increase of the strength of screen printed silicon solar cells by post treatments
The reduction of costs by decreasing the breakage rate is one major purpose of research in solar cell production technology. Fracture and strength analyses identify the metallization process as one of the solar cell processing steps which may severely reduce strength of silicon wafers. Investigations and inspections of fractured wafers and solar cells show that breakage after the firing process often occur along the region where the aluminum electrode print overlaps the silver-aluminum print on the rear side of the cells. These findings are in good agreement with the identification of cracks originating in the overlap. In the present work the mechanisms that lead to crack damages and strength decrease are explained and a method to avoid or compensate this negative effect is suggested.