Lewis Base Passivation of Hybrid Halide Perovskites Slows Electron-Hole Recombination: Time-Domain Ab lnitio Analysis
Lewis Base Passivation of Hybrid Halide Perovskites Slows Electron-Hole Recombination: Time-Domain Ab lnitio Analysis
复制标题
杂化卤化物钙钛矿的路易斯碱钝化减缓电子-空穴复合：时域逐位分析
DOI：
10.1021/acs.jpclett.8b00177
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发表时间：
2018-03-01
影响因子：
5.7
通讯作者：
Prezhdo, Oleg V.
中科院分区：
文献类型：
--
作者：
Liu, Lihong;Fang, Wei-Hai;Prezhdo, Oleg V.
非辐射电子空穴复合在太阳能电池中起着决定光子转换效率的关键作用。实验表明，甲基碘化铅钙钛矿与路易斯碱分子钝化后，复合速率显著降低。结合非绝热分子动力学和时域密度泛函理论，我们发现分子吸附后非辐射电荷复合的速度减慢了一个数量级。噻吩通过传统的钝化机制起作用，迫使电子密度远离表面。相比之下，吡啶将电子定位在表面，而将其能量留在导带边缘附近。这是因为吡啶与钙钛矿的铅原子形成了更强的配位键，并且与噻吩相比，由于氮原子相对于噻吩的硫具有更强的电负性，因此与噻吩相比，吡啶具有更低能量的未占据轨道。两种分子的非绝热耦合和电子相干时间都降低了2倍。广泛的振动模式耦合到电子子系统，产生于无机和有机组件。模拟揭示了钙钛矿钝化提高激发态寿命的原子机制，使实验结果合理化，并促进了我们对钙钛矿太阳能电池中电荷-声子动力学的理解。
Nonradiative electron hole recombination plays a key role in determining photon conversion efficiencies in solar cells. Experiments demonstrate significant reduction in the recombination rate upon passivation of methylammonium lead iodide perovskite with Lewis base molecules. Using nonadiabatic molecular dynamics combined with time-domain density functional theory, we find that the nonradiative charge recombination is decelerated by an order of magnitude upon adsorption of the molecules. Thiophene acts by the traditional passivation mechanism, forcing electron density away from the surface. In contrast, pyridine localizes the electron at the surface while leaving it energetically near the conduction band edge. This is because pyridine creates a stronger coordinative bond with a lead atom of the perovskite and has a lower energy unoccupied orbital compared with thiophene due to the more electronegative nitrogen atom relative to thiophene's sulfur. Both molecules reduce two-fold the nonadiabatic coupling and electronic coherence time. A broad range of vibrational modes couple to the electronic subsystem, arising from inorganic and organic components. The simulations reveal the atomistic mechanisms underlying the enhancement of the excited-state lifetime achieved by the perovskite passivation, rationalize the experimental results, and advance our understanding of charge-phonon dynamics in perovskite solar cells.