Interfacial Engineering of Cu 2 O Passivating Contact for Efficient Crystalline Silicon Solar Cells with an Al 2 O 3 Passivation Layer

Passivating contacts that simultaneously promote carrier selectivity and suppress surface recombination are considered as a promising trend in the crystalline silicon ( c -Si) photovoltaic industry. In this work, efficient p -type c -Si ( p -Si) solar cells with cuprous oxide (Cu 2 O) hole-selective contacts are demonstrated. The direct p -Si/Cu 2 O contact leads to a substoichiometric SiO x interlayer and diffusion of Cu into the silicon substrate, which would generate a deep-level impurity behaving as carrier recombination centers. An Al 2 O 3 layer is subsequently employed at the p -Si/Cu 2 O interface, which not only serves as a passivating and tunneling layer but also suppresses the redox reaction and Cu diffusion at the Si/Cu 2 O interface. In conjunction with the high work function of Au and the superior optical property of Ag, a power conversion efficiency up to 19.71% is achieved with a p -Si/Al 2 O 3 /Cu 2 O/Au/Ag rear contact. This work provides a strategy for reducing interfacial defects and lowering energy barrier height in passivating contact solar cells.