Cui Yu, Liu Xiao-Yi, Ji Shi-Yuan, Sun Yong, Deng Jia-Pei, Ma Xu-Fei, Li Zhi-Qing, Wang Zi-Wu
Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China.
J Phys Chem Lett. 2021 Nov 18;12(45):11182-11190. doi: 10.1021/acs.jpclett.1c02965. Epub 2021 Nov 11.
Quantum defects have been shown to play an essential role in nonradiative recombination in metal halide perovskites (MHPs). Nonetheless, the processes of charge transfer assisted by defects are still ambiguous. Herein, we theoretically study the nonradiative multiphonon processes among different types of quantum defects in MHPs using Markvart's model for the induced mechanisms of electron-electron and electron-phonon interactions. We find that the charge carrier can transfer between the neighboring levels of the same type of shallow defects by multiphonon processes, but it will be distinctly suppressed with an increase in the defect depth. For the nonradiation multiphonon transitions between donor- and acceptor-like defects, the processes are very fast and not sensitive to the defect depth, which provides a possible explanation for the phenomenon of blinking of photoluminescence spectra. We also discuss the temperature dependence of these multiphonon processes and find that their variational trends depend on the comparison of the Huang-Rhys factor with the emitted phonon number. These theoretical results not only fill some of the gaps in defect-assisted nonradiative processes in the perovskite materials but also provide deeper physical insights into producing higher-performance perovskite-based devices.
量子缺陷已被证明在金属卤化物钙钛矿（MHP）的非辐射复合中起着至关重要的作用。尽管如此，由缺陷辅助的电荷转移过程仍然不明确。在此，我们使用Markvart模型对电子 - 电子和电子 - 声子相互作用的诱导机制，从理论上研究了MHP中不同类型量子缺陷之间的非辐射多声子过程。我们发现，电荷载流子可以通过多声子过程在同一类型浅缺陷的相邻能级之间转移，但随着缺陷深度的增加，这种转移将受到明显抑制。对于施主型和受主型缺陷之间的非辐射多声子跃迁，该过程非常快且对缺陷深度不敏感，这为光致发光光谱的闪烁现象提供了一种可能的解释。我们还讨论了这些多声子过程的温度依赖性，发现它们的变化趋势取决于黄 - 里斯因子与发射声子数的比较。这些理论结果不仅填补了钙钛矿材料中缺陷辅助非辐射过程的一些空白，还为制造高性能钙钛矿基器件提供了更深入的物理见解。
