Defect engineering of CH3NH3PbI3 towards enhanced carrier lifetime: combined detailed balanced study and NAMD-TDDFT

Abstract

Halide–lead perovskite materials hold great promise for photovoltaics but face efficiency limitations due to intrinsic defects causing carrier recombination. To enhance cell efficiency, it is imperative to comprehensively understand and manage these defects. In this study, based on first-principles calculations and non-adiabatic molecular dynamics simulations, we established the relationships among chemical potential, defect concentrations and carrier lifetime, and found that precise regulation of the chemical potential in MAPbI₃ can effectively reduce defect concentrations to as low as 10¹¹ cm⁻³, with the dominant defect being V_I⁺¹. The harmful iodine vacancy defects identified in experiments may stem from the non-equilibrium process rather than its inherent defect nature being detrimental. These findings underscore the necessity of reducing defect concentrations to enhance carrier lifetime. Additionally, we observed self-heling behavior exhibited by the defects, enabling partial restoration to the perfect lattice. This work advances our understanding of the defect characteristics and their impact on carrier dynamics, and suggests that defect passivation is a viable strategy to enhance the performance of perovskite solar cells.