Band alignments at interface of Cu2ZnSnS4/ZnO heterojunction: An X-ray photoelectron spectroscopy and first-principles study

The band alignments at the interface of Cu2ZnSnS4 (CZTS)/ZnO heterojunction were determined by X-ray photoelectron spectroscopy. Core levels of S2p and O1s were used to align the valence-band offset (VBO). The VBO was determined to be 1.78 ± 0.10 eV, and the conduction-band offset (CBO) was deduced to be 0.09 ± 0.10 eV, implying that the CZTS/ZnO heterojunction has a type-I band alignment. Furthermore, first-principles calculations based on hybrid functional method also indicate that the CZTS/ZnO interface has a type-I band alignment, well supporting our experimental results.