21.16%-efficiency p-type TOPCon solar cell with ALD-Al2O3/MoOx/Ag as a hole-selective passivating contact

High-performance hole-selective passivating contact is of significance in obtaining the high efficiency of a full-area carriers-selective contact-based solar cell. In this work, we prepared a hole-selective passivating contact of Al2O3/MoOx/Ag and applied it to the rear of the p-type tunneling oxide passivated contact (TOPCon) solar cell. It is found that the ultrathin atomic-layer-deposited (ALD) Al2O3 as a tunneling layer played an essential role in improving the hole selectivity of Al2O3/MoOx/Ag structures, and the optimal thickness of the tunneling layer Al2O3 is ∼ 0.56 nm. An ultra-low resistivity of 1.84 mΩ‧cm2 was obtained on the Al2O3 (0.56 nm)/MoOx (7 nm)/Ag (120 nm) structure. Benefiting from the high-performance hole selectivity, the highest efficiency of 21.16% was successfully achieved on the p-type TOPCon solar cell, which to our knowledge is the highest efficiency of the MoOx-based p-type TOPCon solar cells. This work demonstrates that the hole-selective passivating contact of Al2O3/MoOx/Ag possesses great potential in the full-area carriers-selective contacts based solar cell.