Moderate Humidity Delays Electron-Hole Recombination in Hybrid Organic-Inorganic Perovskites: Time-Domain Ab Initio Simulations Rationalize Experiments
Moderate Humidity Delays Electron-Hole Recombination in Hybrid Organic-Inorganic Perovskites: Time-Domain Ab Initio Simulations Rationalize Experiments
复制标题
中等湿度延迟有机-无机杂化钙钛矿中的电子-空穴复合：时域从头算模拟使实验合理化
DOI：
10.1021/acs.jpclett.6b01412
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发表时间：
2016-08-18
影响因子：
5.7
通讯作者：
Prezhdo, Oleg. V.
中科院分区：
文献类型：
--
作者：
Long, Run;Fang, Weihai;Prezhdo, Oleg. V.
实验表明，有机-无机复合钙钛矿太阳能电池暴露在潮湿环境中，其性能会发生积极和消极的变化。从头算非绝热分子动力学揭示了湿度对非辐射电子-空穴复合的影响。在少量情况下，水分子扰动钙钛矿表面，并将光激电子定位在接近表面的位置。重要的是，避免了深电子陷阱。电子-空穴重叠减少，激发态寿命增加。大量的水形成稳定的氢键网络，具有较高的进入钙钛矿的势垒，对电荷局部化影响不大。同时，通过贡献高频的极性振动，水分子增加了非绝热耦合，加速了复合。总的来说，电子和空穴之间的短相干有利于钙钛矿材料的光伏响应。计算的复合时间尺度与实验符合得很好。时间域原子模拟揭示了湿度对钙钛矿激发态寿命的微观影响，并对相互矛盾的实验观察结果进行了合理的解释。
Experiments show both positive and negative changes in performance of hybrid organic-inorganic perovskite solar cells upon exposure to moisture. Ab initio nonadiabatic molecular dynamics reveals the influence of humidity on nonradiative electron-hole recombination. In small amounts, water molecules perturb perovskite surface and localize photoexcited electron close to the surface. Importantly, deep electron traps are avoided. The electron-hole overlap decreases, and the excited state lifetime increases. In large amounts, water forms stable hydrogen-bonded networks, has a higher barrier to enter perovskite, and produces little impact on charge localization. At the same time, by contributing high frequency polar vibrations, water molecules increase nonadiabatic coupling and accelerate recombination. In general, short coherence between electron and hole benefits photovoltaic response of the perovskites. The calculated recombination time scales show excellent agreement with experiment. The time-domain atomistic simulations reveal the microscopic effects of humidity on perovskite excited-state lifetimes and rationalize the conflicting experimental observations.