Screen-printed n-type industry solar cells with tunnel oxide passivated contact doped by phosphorus diffusion

Abstract Tunnel oxide passivated contact (TOPCon) industrial (244.32 cm2) c-Si solar cell is fabricated in this paper. Both the ultra-thin silicon oxide layer and intrinsic polycrystalline silicon layer are deposited by low-pressure chemical vapor deposited (LPCVD). Then intrinsic polycrystalline silicon layers are doped by thermal diffusion of POCl3 in an industrial-scale quartz tube furnace. Experiment conditions like polycrystalline silicon thickness, diffusion temperature, diffusion time and POCL3 flow rate on the passivation quality of TOPCon structure are investigated in detail and low recombination current density ~8 fA/m2 has been achieved for c-Si/SiOx/poly-Si(70 nm)/SiNx structure at diffusion temperature 850 °C. A variation about 30–40 mV has been observed between the iVoc and Voc for 70 nm samples, which should be attributed to the metallization-induced degration. Not consistent with the result obtained from symmetric samples, both an improvement to the solar cell efficiency has been found for 70 nm thick poly-Si and 170 nm thick poly-Si at the diffusion temperature above the optimal diffusion temperature. Finally, by optimizing the polysilion thickness and phosphorus diffusion, the champion solar cell efficiency of 22.81% is achieved, with Voc of 702.6 mV, Jsc of 39.78 mA/cm2, FF of 81.62%.