Ma Xinbo, Tian Xuesong, Stippell Elizabeth, Prezhdo Oleg V, Long Run, Fang Wei-Hai
College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, PR China.
Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
J Am Chem Soc. 2024 Oct 23;146(42):29255-29265. doi: 10.1021/jacs.4c12634. Epub 2024 Oct 11.
Halide interstitial defects severely hinder the optoelectronic performance of metal halide perovskites, making research on their passivation crucial. We demonstrate, using ab initio nonadiabatic molecular dynamics simulations, that hydrogen vacancies (H) at both N and C atoms of the methylammonium (MA) cation in MAPbI efficiently passivate iodine interstitials (I), providing a self-passivation strategy for dealing with the H and I defects simultaneously. H at the N site (H) introduces a defect state into the valence band, while the state contributed by H at the C site (H) evolves from a shallow level at 0 K to a deep midgap state at ambient temperature, exhibiting a high environmental activity. Both H and H are strong Lewis bases, capable of capturing and passivating I defects. H is a stronger Lewis base, bonds with I better, and exhibits a more pronounced passivation effect. The charge carrier lifetimes in the passivated systems are significantly longer than in those containing either H or I, and even in pristine MAPbI. Our demonstration of the H and I defect self-passivation in MAPbI suggests that systematic control of the relative concentrations of H and I can simultaneously eliminate both types of defects, thereby minimizing charge and energy losses. The demonstrated defect self-passivation strategy provides a promising means for defect control in organic-inorganic halide perovskites and related materials and deepens our atomistic understanding of defect chemistry and charge carrier dynamics in solar energy and optoelectronic materials.
卤化物间隙缺陷严重阻碍了金属卤化物钙钛矿的光电性能，因此对其钝化的研究至关重要。我们通过从头算非绝热分子动力学模拟表明，在MAPbI中，甲铵（MA）阳离子的N和C原子处的氢空位（H）能够有效地钝化碘间隙（I），为同时处理H和I缺陷提供了一种自钝化策略。N位点的H（H）在价带中引入了一个缺陷态，而C位点的H（H）贡献的态从0 K时的浅能级演变为室温下的深带隙中间态，表现出较高的环境活性。H和H都是强路易斯碱，能够捕获并钝化I缺陷。H是更强的路易斯碱，与I结合得更好，钝化效果更显著。钝化体系中的电荷载流子寿命明显长于含有H或I的体系，甚至长于原始的MAPbI。我们对MAPbI中H和I缺陷自钝化的证明表明，系统控制H和I的相对浓度可以同时消除这两种类型的缺陷，从而将电荷和能量损失降至最低。所展示的缺陷自钝化策略为有机-无机卤化物钙钛矿及相关材料中的缺陷控制提供了一种有前景的方法，并加深了我们对太阳能和光电子材料中缺陷化学和电荷载流子动力学的原子尺度理解。
