Flexible Substrate‐Structured Sb₂S₃ Solar Cells with Back Interface Selenization

Abstract Antimony sulfide (Sb₂S₃) with a 1D molecular structure has strong bending characteristics, showing great application potential in flexible devices. Herein, the flexible substrate‐structured Sb₂S₃ solar cells is developed and improve device performances by the back interface selenization. The high‐quality Sb₂S₃ film with an optimal thickness of 1.8 µm, ensuring efficient spectra utilization, is deposited on flexible Mo foils by the rapid thermal evaporation technique. To solve the issues of back interfacial recombination and charge transport, the 20 nm MoSe₂ layer between Sb₂S₃ film and Mo foil is fabricated by substrate selenization in the tube furnace. Further investigations indicate that the MoSe₂ layer improves the interfacial energy band alignments and induces the [hk1] orientation of Sb₂S₃ film, thereby passivating defects and enhancing the carrier transport capacity. The flexible solar cell in the structure of Mo foil/MoSe₂/Sb₂S₃/CdS/ITO/Ag, exhibiting good flexibility to stand thousands of bending, achieves an efficiency of 3.75%, which is the highest for Sb₂S₃ devices in substrate configuration. The presented flexible structure and back interfacial selenization study will provide new prospects for inorganic Sb₂S₃ thin film solar cells.