One-Step Vapor Transport Deposition for Tuning the Photovoltaic Performance of SnSxSe1–x Solar Cells: Analysis of the Improved Voc and Jsc

Binary tin chalcogenides (SnS and SnSe) are investigated extensively for thin-film solar cells (TFSCs). The conventional sulfo-selenization of elemental Sn follows multiple and rigorous procedures. Herein, we have developed a one-step procedure for developing a mixed-phase SnSxSe1–x thin film. Meanwhile, reports on synthesizing mixed-phase SnSxSe1–x (0 < x < 1) thin films for TFSCs are scarce. In this study, SnSxSe1–x thin films are synthesized by vapor transport deposition using a mixture of SnS and SnSe source powders for evaporation. Energy-dispersive X-ray spectroscopy analysis confirmed the formation of homogeneous and uniformly distributed ternary SnSxSe1–x alloys. The corresponding X-ray diffraction patterns revealed that the 2θ values of the characteristic (111) peak of the orthorhombic structure shifted toward a lower angle as the Se-content increased owing to the expansion of the lattice constant. The S-rich SnSxSe1–x devices exhibited a superior Voc, while the Se-rich devices displayed a superior Jsc. The highest efficiency of 3.75% was achieved for the optimized SnS0.70Se0.30 absorber layer, which is significantly higher than those of pure SnS or SnSe devices.