Exploring Low-Energy Pathways for Self-Healing Defects in CsPbBr₃—A Computational Study

Metal halide perovskites (MHPs) have become a mainstay of recent research into solar cell materials, given their photovoltaic properties and remarkable solar efficiency in the lab. However, their efficiency and stability, especially at scale, are intricately linked to the material’s ability to manage defects, which can act as recombination centers and limit their overall performance.<br/>The all-inorganic perovskite, CsPbBr₃, has shown promising durability against environmental degradation factors, making it a prime candidate for defect studies aimed at improving device performance and longevity.While the available literature contains some defect formation energies, mechanistic understanding of defect motion is currently limited, especially for all-inorganic MHP materials. Our work investigates atomic-scale mechanisms behind defect migration and recombination in CsPbBr₃, using a Nudged Elastic Band method combined with Density Functional Theory calculations (NEB-DFT). This approach allows us to estimate activation energies from defect formation and migration, providing insight into at least some of the dominant defect pathways. Motivated by Tirmzi <i>et al.</i>’s experimental measurements of the slow recovery of light-induced conductivity in CsPbBr₃, we have identified some low-energy pathways that could lead to the self-healing of defects, a phenomenon that would significantly enhance the material’s defect tolerance compared to conventional photovoltaic materials. Our NEB-DFT results match the sole experimental activation energy, shedding light on plausible defect migration pathways in CsPbBr₃. These low-energy pathways for defect self-healing may have significant implications for the design of semiconductor materials with improved light absorption and catalysis properties, aligning with the symposium’s focus on advances in photocatalysis, operando material characterization, and material design for solar energy conversion.