Oxygen Content Modulation Toward Highly Efficient Sb2Se3 Solar Cells

Vapor-transport deposition (VTD) method is the main technique for the preparation of Sb₂Se₃ films. However, oxygen is often present in the vacuum tube in such a vacuum deposition process, and Sb₂O₃ is formed on the surface of Sb₂Se₃ because the bonding of Sb-O is formed more easily than that of Sb-Se. In this work, the formation of Sb₂O₃ and thus the carrier transport in the corresponding solar cells were studied by tailoring the deposition microenvironment in the vacuum tube during Sb₂Se₃ film deposition. Combined by different characterization techniques, we found that tailoring the deposition microenvironment can not only effectively inhibit the formation of Sb₂O₃ at the CdS/Sb₂Se₃ interface but also enhance the crystalline quality of the Sb₂Se₃ thin film. In particular, such modification induces the formation of (hkl, l = 1)-oriented Sb₂Se₃ thin films, reducing the interface recombination of the subsequently fabricated devices. Finally, the Sb₂Se₃ solar cell with the configuration of ITO/CdS/Sb₂Se₃/Spiro-OMeTAD/Au achieves a champion efficiency of 7.27%, a high record for Sb₂Se₃ solar cells prepared by the VTD method. This work offers guidance for the preparation of high-efficiency Sb₂Se₃ thin-film solar cells under rough-vacuum conditions.