Strontium-doped low-temperature-processed CsPbI₂Br perovskite solar cells

Cesium (Cs) metal halide perovskites for photovoltaics have gained research interest due to their better thermal stability compared to their organic–inorganic counterparts. However, demonstration of highly efficient Cs-based perovskite solar cells requires high annealing temperature, which limits their use in multijunction devices. In this work, low-temperature-processed cesium lead (Pb) halide perovskite solar cells are demonstrated. We have also successfully incorporated the less toxic strontium (Sr) at a low concentration that partially substitutes Pb in CsPb_1–xSr_xI₂Br. The crystallinity, morphology, absorption, photoluminescence, and elemental composition of this low-temperature-processed CsPb_1–xSr_xI₂Br are studied. It is found that the surface of the perovskite film is enriched with Sr, providing a passivating effect. At the optimal concentration (x = 0.02), a mesoscopic perovskite solar cell using CsPb_0.98Sr_0.02I₂Br achieves a stabilized efficiency at 10.8%. This work shows the potential of inorganic perovskite, stimulating further development of this material.