Unexpectedly weak phase dependence of defect-assisted nonradiative recombination in halide perovskites

Abstract

Understanding the behavior of deep-level defects in different phases of halide perovskites is central to phase engineering of perovskite optoelectronics. Prior first-principles calculations have indicated that the transition levels of deep defects may vary drastically across different phases of halide perovskites. Since locations of the transition levels are decisive for the defect-assisted nonradiative carrier capture coefficients, it is expected that the same defect may behave distinctly for nonradiative recombination across different perovskite phases. Using the key recombination center-iodine interstitials (I_i ) in the prototypical halide perovskite CsPbI₃ as an example, here we show that despite the quantitatively very different transition levels in different phases, the total nonradiative capture coefficient of I_i has an unexpectedly weak phase dependence due to strong lattice anharmonicity. Our study will guide the actively ongoing research efforts to further enhance the performance of perovskite optoelectronics.