Synthesis and Photovoltaic Characterization of Cs₃Sb₂Br₉ Thin Films

Inorganic antimony halides with the general formula A 3 Sb 2 X 9 have emerged as promising materials for photovoltaic applications due to their low toxicity and high stability. However, achieving high‐quality thin‐film morphology with this class of materials remains challenging, which adversely affects performance of the solar cell devices. In this work, a facile synthesis procedure is demonstrated for the fabrication of highly crystalline and pinhole‐free Cs 3 Sb 2 Br 9 thin films by introducing a post‐annealing process in a solvent‐rich atmosphere. Stability of the resulting Cs 3 Sb 2 Br 9 films on a timescale of 3 days under ambient conditions at 60% relative humidity is demonstrated. Photovoltaic performance of the Cs 3 Sb 2 Br 9 films is assessed using a standard n‐i‐p configuration, which produces a power conversion efficiency of 0.173% ± 0.014% under simulated 1 sun irradiation, which represents an improvement compared to the lower efficiency (0.053% ± 0.006%) observed in Cs 3 Sb 2 Br 9 films prepared using conventional methods.