Liu Yulong, Fang Wei-Hai, Long Run
College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China.
J Phys Chem Lett. 2024 Apr 11;15(14):3764-3771. doi: 10.1021/acs.jpclett.4c00657. Epub 2024 Mar 29.
In this study, we developed a machine-learned force field for CsPbI using a neural network potential, enabling molecular dynamics simulations (MD) with ab initio accuracy over nanoseconds. This approach, combined with ab initio MD and nonadiabatic MD, was used to study the charge trapping and recombination dynamics in both pristine and defective CsPbI. Our simulations revealed key transitions affecting carrier lifetimes, especially in systems with iodine vacancy and interstitial iodine defects. An iodine trimer, formed when iodine replaces cesium, exhibits a high-frequency phonon mode. This mode enhances nonadiabatic coupling, accelerating charge recombination in defective systems compared to pristine ones. In the iodine vacancy system, recombination times varied significantly due to differences in NA coupling and energy gaps. The interplay between nonadiabatic coupling and pure dephasing time is crucial in determining recombination times for interstitial iodine defects. Our findings highlight the role of defect evolution in perovskites, offering insights for enhancing perovskite performance.
在本研究中，我们使用神经网络势为CsPbI开发了一种机器学习力场，能够进行具有从头算精度的纳秒级分子动力学模拟（MD）。这种方法与从头算MD和非绝热MD相结合，用于研究原始和有缺陷的CsPbI中的电荷俘获和复合动力学。我们的模拟揭示了影响载流子寿命的关键转变，特别是在具有碘空位和间隙碘缺陷的系统中。当碘取代铯时形成的碘三聚体表现出高频声子模式。与原始系统相比，这种模式增强了非绝热耦合，加速了有缺陷系统中的电荷复合。在碘空位系统中，由于NA耦合和能隙的差异，复合时间有显著变化。非绝热耦合与纯退相时间之间的相互作用对于确定间隙碘缺陷的复合时间至关重要。我们的研究结果突出了缺陷演化在钙钛矿中的作用，为提高钙钛矿性能提供了见解。
