Enhanced separation efficiency of photoinduced charges for antimony-doped tin oxide (Sb-SnO_2)/TiO_2 heterojunction semiconductors with varied Sb doping concentration

摘要

In this paper, antimony-doped tin oxide (Sb-SnO_2) nanoparticles were synthesized with varied Sb doping concentration, and the Sb-SnO_2/TiO_2 heterojunction semiconductors were prepared with Sb-SnO_2 and TiO_2. The separation efficiency of photoinduced charges was characterized with surface photovoltage (SPV) technique. Compared with Sb-SnO_2 and TiO_2, Sb-SnO_2/TiO_2 presents an enhanced separation efficiency of photoinduced charges, and the SPV enhancements were estimated to be 1.40, 1.43, and 1.99 for Sb-SnO_2/TiO_2 composed of Sb-SnO_2 with the Sb doping concentration of 5%, 10%, and 15%, respectively. To understand the enhancement, the band structure of Sb-SnO_2 and TiO_2 in the heterojunction semiconductor was determined, and the conduction band offsets (CBO) between Sb-SnO_2 and TiO_2 were estimated to be 0.56, 0.64, and 0.98 eV for Sb-SnO_2/TiO_2 composed of Sb-SnO_2 with the Sb doping concentration of 5%, 10%, and 15%, respectively. These results indicate that the separation efficiency enhancement is resulting from the energy level matching, and the increase of enhancement is due to the rising of CBO.