Enhancing Stability of Microwave‐Synthesized Cs2SnxTi1‐xBr6 Perovskite by Cation Mixing

The double‐perovskite material Cs2TiBr6 shows excellent photovoltaic potential, making it a promising alternative to lead‐based materials. However, its high susceptibility to degradation in air has raised concerns about its practical application. This study introduces an interesting synthesis approach that significantly enhances the stability of Cs2TiBr6 powder. We implemented a gradual cation exchange process by substituting Ti4+ with Sn4+ in the efficient microwave‐assisted synthesis method, developing a double perovskite Cs2SnxTi1‐xBr6 type. A systematic study of increasing concentration of Sn4+ in Cs2TiBr6 perovskite has been performed to analyze the effect of Sn‐doping degree on the chemical and thermal stability of the material and the optical features in both nitrogen and ambient atmospheres, significantly increasing the stability of the material in the air for over a week. Furthermore, introducing Sn4+ results in a more uniform polygonal crystal morphology of the powders and a slight band gap broadening. We show that microwave‐assisted synthesis is highly efficient and cost‐effective in producing more sustainable lead‐free perovskite materials with enhanced stability and desirable electrical characteristics. This work suggests a promising method for synthesizing perovskite materials, opening new routes for scientific research and applications.