First-principles study on electronic and optical properties of perovskite light-emitting diodes CsPb(Br1<b>−</b> <i>x</i>I<i>x</i>)3

Abstract

CsPb(Br1−xIx)3, a mixed-halide all-inorganic perovskite, is a promising light-emitting diode (LED) material due to its impressive performance. It has been demonstrated that the mixing parameter x of halogen composition significantly influences the luminescence efficiency of CsPb(Br1−xIx)3. However, the underlying microscopic mechanisms remain unclear. Using first-principles calculations, we investigate the effects of anion mixing on the radiative and non-radiative recombination properties of perovskite materials. Simulations on the carrier mobility, exciton binding energy, affinity energy, and defect formation energy of the materials in the CsPb(Br1−xIx)3 system collaboratively revealed that a high ratio off Br is associated with enhanced luminescence efficiency. Specifically, CsPb(Br1−xIx)3 exhibits optimal luminescent performance with a 2:1 bromine-to-iodine ratio, while it shows the performance degradation with a 1:1 ratio. The results demonstrate that the ratio of halogen atoms (Br and I) has a significant influence on the LED properties of cesium-based all-inorganic perovskites CsPb(Br1−xIx)3, providing a valuable guide for the experimental preparation of cesium-based all-inorganic perovskites.