Industrial PERL-Type Si Solar Cells With Efficiencies Exceeding 19.5

In this paper, we describe a path toward industrial passivated emitter, rear locally diffused (PERL)-type crystalline Si solar cells with efficiencies exceeding 19.5%. The impact of thickness and quality of different local back surface field (BSF) pastes on the extended laser ablation (ELA) rear contacting technique is investigated, and the effect of the wafer resistivity and emitter diffusion/oxidation processes on cell performance is evaluated. Based on these investigations, an optimized process flow for PERL-type monocrystalline Si solar cells is defined, and its capability is tested against that of standard Al-BSF in large batch experiments, demonstrating a top efficiency of 19.7%, a 19.5% average efficiency, and an efficiency increase of about 1% abs. with respect to Al-BSF cells.