Characterizing ZnMgO/Sb2Se3 Interface for Solar Cell Applications

This study investigates the band alignment of the Zn0.8Mg0.2O/Sb2Se3 interface structure to improve solar cell performance. Sb2Se3 is a promising absorber material. However, Sb2Se3 solar cells exhibit a lower conversion efficiency than CuInGaSe2 and CdTe solar cells. The lower efficiency of Sb2Se3 solar cells is attributed to the severe open-circuit voltage loss caused by the band structure at the buffer/Sb2Se3 interface. Sb2Se3 solar cells typically employ CdS as the buffer layer, and the CdS/Sb2Se3 interface exhibits a cliff structure, which results in interfacial recombination. By contrast, a ZnMgO buffer layer can form a spike structure with Sb2Se3 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 Sb2Se3. 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 Zn0.8Mg0.2O/Sb2Se3 interface is characterized via interface-induced band bending. The Zn0.8Mg0.2O/Sb2Se3 interface exhibits a spike structure with a positive delta conduction band offset of +0.193 eV.