19% Efficient Inline-diffused Large-area Screen-printed Al-LBSF Silicon Wafer Solar Cells

Abstract

Presently, large-area high-efficiency (> 19%) screen printed p-type silicon solar cells are dominated by the aluminium local back surface field (Al-LBSF) technology. However, all those cells were fabricated with tube diffused emitters. Inline diffusion, using phosphoric acid as the dopant source, offers potentially low-cost emitter formation for p-type silicon wafer solar cells. To achieve higher efficiencies for these solar cells, the authors have applied a new Si etch solution to remove the dead layer of the inline diffused emitter. Efficiencies up to 18.3% were obtained for standard Al back surface field (Al-BSF) solar cells. In this work, the same etch-back process was applied to Al-LBSF devices. We report a maximum efficiency of 19.0%, an average batch efficiency of 18.9% (± 0.1% StDev), and a maximum open-circuit voltage of 640mV for the cells, using industry-grade p-type 6 inch wide pseudosquare Cz mono-Si wafers. These results indicate that inline-diffused emitters can be used in high-efficiency silicon wafer solar cells.