Contributions of conduction band offset to the enhanced separation efficiency of photoinduced charges for SrTiO3/Bi2O3 heterojunction semiconductor

●Heterojunction semiconductor of SrTiO3/Bi2O3 was prepared.●SrTiO3/Bi2O3 presents enhanced separation efficiency.●Conduction band offset between SrTiO3 and Bi2O3 is quantified.●Recombination rate of SrTiO3/Bi2O3 decreases compared with single phases.

SrTiO3/Bi2O3 heterojunction semiconductor was prepared and characterized by X-ray diffraction, UV–vis absorption spectrum, and scanning electron microscope, surface photovoltage spectroscopy, and photoluminescence spectroscopy. The surface photovoltage spectra indicate that the separation efficiency of photoinduced charges for SrTiO3/Bi2O3 was enhanced compared with that of SrTiO3 or Bi2O3. The energy band diagram of SrTiO3/Bi2O3 heterojunction was directly determined with X-ray photoelectron spectroscopy, and the conduction band offset between SrTiO3 and Bi2O3 was quantified to be 0.28±0.03 eV. The photoluminescence spectra display that the recombination rate of photoinduced carriers for SrTiO3/Bi2O3 decreases compared with that of SrTiO3 or Bi2O3, which is mainly due to the energy levels matching between them. Therefore the enhanced separation efficiency of photoinduced charges is resulting from the energy difference between the conduction band edges of SrTiO3 and Bi2O3.

Enhanced separation efficiency for SrTiO3/Bi2O3 is resulting from the energy difference between the conduction band edges.Figure optionsDownload as PowerPoint slide