Patterned Borosilicate Glass by a Simplified Flash Foam Stamping Technique as a Back Passivation Layer for Photovoltaic Structure

The rear surface passivation by a localized dielectric layer for high efficiency silicon solar cells has significant advantages compared with the standard fully covered metal back-contact structure. In this study, partial borosilicate glass (BSG) layer used as rear dielectric passivation of localized back contacts was taken advantage for a local back surface field (LBSF) solar cell, while typically it has been removed after thermal diffusion process finished. A simplified flash foam stamping technique has been initially exploited in the single-step process to pattern a localized back BSG passivation. These low cost, simple technique and scalable process have to be considered promising in the high efficiency of commercial solar cells. Acid stamp narrowly removes BSG in order to open the contact area between metal and p-Si substrate. The aperture ratio of the BSG pattern is varied from 5 - 20%. The LBSF solar cell with a localized back BSG passivation showed an increase in open voltage, fill factor and power conversion efficiency by 4.88%, 1.43%, and 0.67%, respectively, compared to a sample without LBSF layer. Therefore, this non-complex process using flash foam stamp is an alternative production procedure to have co-operated effectively with solar cell industrial production for power efficiency improvement.