Characterizing ZnMgO/Sb 2 Se 3 Interface for Solar Cell Applications

This study investigates the band alignment of the Zn 0.8 Mg 0.2 O/Sb 2 Se 3 interface structure to improve solar cell performance. Sb 2 Se 3 is a promising absorber material. However, Sb 2 Se 3 solar cells exhibit a lower conversion efficiency than CuInGaSe 2 and CdTe solar cells. The lower efficiency of Sb 2 Se 3 solar cells is attributed to the severe open‐circuit voltage loss caused by the band structure at the buffer/Sb 2 Se 3 interface. Sb 2 Se 3 solar cells typically employ CdS as the buffer layer, and the CdS/Sb 2 Se 3 interface exhibits a cliff structure, which results in interfacial recombination. By contrast, a ZnMgO buffer layer can form a spike structure with Sb 2 Se 3 at their interface, which reduces recombination and, as a result, enhances conversion efficiency. Therefore, this study employs the ZnMgO buffer layer and analyzes their material properties with various Mg contents and band structure at buffer/absorber layer interface. A ZnMgO buffer layer is sputter‐deposited on Sb 2 Se 3 . The optical bandgap of ZnMgO is 3.3–3.72 eV, corresponding to an Mg content of 0–0.35 at%. The carrier concentration indicates an appropriate doping level ranging from 10 14 to 10 16 cm −3 . The Zn 0.8 Mg 0.2 O/Sb 2 Se 3 interface is characterized via interface‐induced band bending. The Zn 0.8 Mg 0.2 O/Sb 2 Se 3 interface exhibits a spike structure with a positive delta conduction band offset of +0.193 eV.