Band alignment of Sb_2O_3 and Sb_2Se_3

摘要

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 Sb2Se3 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.