Efficiency Improvement of NiO_x‐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.