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Control of Hot Carrier Cooling in Lead Halide Perovskites by Point Defects
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2022-09-20 , DOI: 10.1021/jacs.2c08487
Zhaobo Zhou 1, 2 , Junjie He 2, 3 , Thomas Frauenheim 2, 4, 5 , Oleg V Prezhdo 6 , Jinlan Wang 1
Affiliation  

Hot carriers (HCs) in lead halide perovskites are prone to rapidly relax at the band edge and waste plentiful photon energy, severely limiting their conversion efficiency as HC photovoltaic devices. Here, the HC cooling dynamics of MAPbI3 perovskite with common vacancy point defects (e.g., MAv+ and Iv) and an interstitial point defect (e.g., Ii) is elucidated, and the underlying physics is explicated using ab initio nonadiabatic molecular dynamics. Contrary to vacancy point defects, the interstitial point defect reduces the band degeneracy, decreases the HC −phonon interaction, weakens the nonadiabatic coupling, and ultimately slows down hot electron cooling by a factor of 1.5–2. Furthermore, the band-by-band relaxation pathway and direct relaxation pathway are uncovered for hot electron cooling and hot hole cooling, respectively, explaining why hot electrons can store more energy than hot holes during the cooling process. Besides, oxygen molecules interacting with Ii sharply accelerate the hot electron cooling, making it even faster than that of the pristine system and revealing the detrimental effect of oxygen on HC cooling. This work provides significant insights into the defect-dependent HC cooling dynamics and suggests a new strategy to design high-efficiency HC photovoltaic devices.

中文翻译:

点缺陷对卤化铅钙钛矿热载流子冷却的控制

卤化铅钙钛矿中的热载流子 (HC) 容易在能带边缘快速弛豫并浪费大量光子能量,严重限制了其作为 HC 光伏器件的转换效率。在这里,MAPbI 3钙钛矿的 HC 冷却动力学具有常见的空位点缺陷(例如,MA v +和 I v )和间隙点缺陷(例如,I i ) 被阐明,并使用从头算非绝热分子动力学来解释基础物理。与空位缺陷相反,间隙点缺陷减少了能带简并,减少了 HC -声子相互作用,削弱了非绝热耦合,并最终将热电子冷却减慢了 1.5-2 倍。此外,分别揭示了热电子冷却和热空穴冷却的逐带弛豫路径和直接弛豫路径,这解释了为什么在冷却过程中热电子比热空穴存储更多的能量。此外,与 I i相互作用的氧分子急剧加速热电子冷却,使其比原始系统更快,并揭示了氧气对 HC 冷却的不利影响。这项工作为与缺陷相关的 HC 冷却动力学提供了重要的见解,并提出了一种设计高效 HC 光伏器件的新策略。
更新日期:2022-09-20
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