Synthesis and Photovoltaic Characterization of Cs₃Sb₂Br₉ Thin Films

Inorganic antimony halides with the general formula A₃Sb₂X₉ 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 Cs₃Sb₂Br₉ thin films by introducing a post-annealing process in a solvent-rich atmosphere. Stability of the resulting Cs₃Sb₂Br₉ films on a timescale of 3 days under ambient conditions at 60% relative humidity is demonstrated. Photovoltaic performance of the Cs₃Sb₂Br₉ 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 Cs₃Sb₂Br₉ films prepared using conventional methods.