High-performance SiOx/MgOx electron-selective contacts for crystalline silicon solar cells

High carrier recombination loss at the metal and silicon contact regions is one of the dominant factors constraining the power conversion efficiency (PCE) of crystalline silicon (c-Si) solar cells. Metal compound-based carrier-selective contacts are being intensively developed to address this issue. In this work, we present a high-performance electron-selective SiOx/MgOx contact for c-Si solar cells. The SiOx/MgOx stack is prepared by thermally-grown SiOx (similar to 0.7 nm) and thermally-evaporated MgOx (similar to 1.0 nm). The electron selectivity of SiOx/MgOx contact is investigated by measuring the surface passivation and the contact resistivity (rho(c)) on the c-Si surface. The results demonstrate that optimized SiOx/MgOx contact displays a very low rho(c) (3.4 m Omega cm(2)) and a good surface passivation on an n-type c-Si surface simultaneously. A high PCE of 21.1% is achieved on an n-type c-Si solar cell featuring a full-area SiOx/MgOx rear contact.