Efficiency Improvement of NiOx-Based Hole Transport Layers in Passivated Contact Crystalline Silicon Solar Cells

Passivated contact crystalline silicon (c-Si) solar cells with nickel oxide (NiO_x) as a hole transport layer (HTL) are a promising and efficient solar cell that has received much attention. However, the current low open circuit voltage (V_oc) and low stability of c-Si solar cells with NiO_x as the HTL are due to the bad passivation and the ion diffusion, which has limited the development of NiO_x-based c-Si solar cells. Herein, the performance of doping-free asymmetric passivated contact c-Si heterojunction solar cells is improved by using hydrogen-doped aluminum oxide (HAl₂O₃) as the passivation layer and annealing in forming gas (nitrogen, hydrogen mixture FGA), as well as by introducing an economically saving composite Ni/Ag electrode. Finally, a 20.29% power conversion efficiency is achieved from p-Si/HAl₂O₃(FGA)/NiO_x/Ni/Ag back-contact c-Si solar cells, which is the highest efficiency reported so far for c-Si solar cells with NiO_x as the HTLs. Furthermore, the efficiency of the p-Si/HAl₂O₃(FGA)/NiO_x/Ni/Ag remains above 20% after 30 days of storage in an atmospheric environment, demonstrating its long-term stability. This study demonstrates the potential for industrialization of NiO_x-based HTL c-Si solar cells with high performance and high stability.