Stabilization of Photoactive γ-CsPbI₃ Perovskite Phase by Incorporation of Mg

Fully inorganic CsPbI3 perovskite has been widely explored as an alternative light-harvesting material owing to its superior thermal stability over the organic–inorganic halide perovskite and the suitable band gap. However, stabilization of the photoactive CsPbI3 phase at room temperature (RT) remains the biggest challenge. The photoactive α-CsPbI3 which requires high-temperature synthesis (above 320 °C) transforms into the photoactive γ-CsPbI3 at RT and on exposure to ambient rapidly transforms into the non-photoactive δ-CsPbI3. Herein, we investigate the effect of incorporating Mg2+ in the CsPbI3 lattice. It has been found that the photoactive γ-phase of CsPbI3 can be stabilized for more than 167 days at RT in a nitrogen atmosphere by incorporating Mg2+ inside the lattice. Incorporating Mg2+ inside the lattice of CsPbI3 has led to enhanced optoelectronic properties along with enhanced phase and thermal stability.