Band alignment of Sb2O3 and Sb2Se3

Antimony selenide (Sb 2Se 3) possesses great potential in the field of photovoltaics (PV) due to its suitable properties for use as a solar absorber and good prospects for scalability. Previous studies have reported the growth of a native antimony oxide (Sb 2O 3) layer at the surface of Sb 2Se 3 thin films during deposition and exposure to air, which can affect the contact between Sb 2Se 3 and subsequent layers. In this study, photoemission techniques were utilized on both Sb 2Se 3 bulk crystals and thin films to investigate the band alignment between Sb 2Se 3 and the Sb 2O 3 layer. By subtracting the valence band spectrum of an in situ cleaved Sb 2Se 3 bulk crystal from that of the atmospherically contaminated bulk crystal, a valence band offset (VBO) of − 1.72 eV is measured between Sb 2Se 3 and Sb 2O 3. This result is supported by a − 1.90 eV VBO measured between Sb 2O 3 and Sb 2Se 3 thin films via the Kraut method. Both results indicate a straddling alignment that would oppose carrier extraction through the back contact of superstrate PV devices. This work yields greater insight into the band alignment of Sb 2O 3 at the surface of Sb 2Se 3 films, which is crucial for improving the performance of these PV devices.