Flexible Substrate‐Structured Sb2S3 Solar Cells with Back Interface Selenization

Abstract Antimony sulfide (Sb 2 S 3 ) with a 1D molecular structure has strong bending characteristics, showing great application potential in flexible devices. Herein, the flexible substrate‐structured Sb 2 S 3 solar cells is developed and improve device performances by the back interface selenization. The high‐quality Sb 2 S 3 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 MoSe 2 layer between Sb 2 S 3 film and Mo foil is fabricated by substrate selenization in the tube furnace. Further investigations indicate that the MoSe 2 layer improves the interfacial energy band alignments and induces the [hk1] orientation of Sb 2 S 3 film, thereby passivating defects and enhancing the carrier transport capacity. The flexible solar cell in the structure of Mo foil/MoSe 2 /Sb 2 S 3 /CdS/ITO/Ag, exhibiting good flexibility to stand thousands of bending, achieves an efficiency of 3.75%, which is the highest for Sb 2 S 3 devices in substrate configuration. The presented flexible structure and back interfacial selenization study will provide new prospects for inorganic Sb 2 S 3 thin film solar cells.