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.
Keywords: Sb2Se3 solar cell; carrier transport; efficiency; growth orientation; interface recombination.