Si-rich SiNx rear passivated c-Si solar cell with a novel antimony Local Back Surface Field formed by Laser Fired Contact

Abstract

Local Back Contact (LBC) crystalline silicon solar cell with novel antimony (Sb) Local Back Surface Field (LBSF) are reported. The Sb LBSF is formed at low temperature with a Laser Fired Contacts (LFC) process. To improve the solar cell parameters of Sb LBSF, the rear passivation layer with SiNx is optimized by varying the refractive index. The Si-rich SiNx with a refractive index (n) of 2.7 possesses high lifetime of 2 ms with reduced absorption at a longer wavelength. The increase in lifetime is analyzed with Si–H bond concentration by FTIR. A 100 nm thick Sb layer with low laser power of 44 mW resulted in a junction depth of 500 nm with a carrier concentration of 5 × 1020 cm−3. The improved rear passivation with Si-rich SiNx, the optimized Sb thickness yielded the best electrical results, with open circuit voltage (Voc) of 643 mV and efficiency of 19.25%, compared to the reference cell with Voc of 625 mV and efficiency of 18.20%.