Improved Bifacial Properties Of P-Type Passivated Emitter And Rear Cell Solar Cells Toward High Mass Production Efficiency

The p-type passivated emitter and rear cell (PERC) has achieved great success, and the bifacial PERC product is predicted as the mainstream of photovoltaic market. Herein, the higher diffusion sheet resistance on laser-doped selective emitter combined with different rear-side laser ablation designs and their impact on passivation and electrical performance are investigated. A high diffusion sheet resistance can restrain front surface recombination and improve short-wavelength spectral response. The minority carrier lifetime evolution is evaluated on a semi-PERC structure, which is significantly affected by the laser ablation design on the rear surface. The measured efficiency analysis reveals that there is a negative relation between enlarged laser ablation area and open-circuit voltage. The conversion efficiency of bifacial PERC cells with dash ablation design increases by 0.29% (absolute efficiency gain) comparing with base line samples with straight-line ablation. A high front-side average efficiency of 22.34% and a high bifaciality of 76.87% are achieved and further optimized to 22.52% and 78%, respectively, for a p-type PERC cell in a mass production line. After applying a multipassivation structure and careful optimization, an impressive mass production efficiency of 23.24% is achieved recently, showing great potential for low-cost photovoltaic power generation.