Microstructural and Optical Properties of Sb 2 S 3 Film Thermally Evaporated from Antimony Pentasulfide and Efficient Planar Solar Cells

Antimony sulfide (Sb 2 S 3 ) thin film is a promising light absorber for solar cell application due to its suitable bandgap, high absorption coefficient, and non‐toxic constituents. However, thermally evaporated Sb 2 S 3 thin films experience sulfur loss during evaporation and post‐annealing, which do harm to the film quality and the performance of the devices. In this work, for the first time Sb 2 S 3 thin films are prepared by thermally evaporating antimony pentasulfide (Sb 2 S 5 ) precursor. The thermal and microstructural properties of Sb 2 S 3 and Sb 2 S 5 precursors are studied and compared. The crystallization of the Sb 2 S 3 film (S‐5) prepared from Sb 2 S 5 precursor is inferior to that (S‐3) from Sb 2 S 3 powder. And the annealed S‐5 film shows a larger bandgap of 1.69 eV than S‐3. However, compared with S‐3, planar S‐5 thin film solar cells in the configuration of glass/(SnO 2 :F) FTO/TiO 2 /Sb 2 S 3 /Spiro‐OMeTAD/Ag exhibit an apparently improved photovoltaic performance, with the best power conversion efficiency of 3.75% and high fill factor of 0.56, which is the highest efficiency of thermally evaporated planar Sb 2 S 3 solar cell. The capacitance–voltage ( C–V ) measurement indicates that this might come from the higher C–V derived space‐charge density in S‐5. This work offers a new method to prepare Sb 2 S 3 thin films for efficient solar cells.