Dynamical Origin of the Rashba Effect in Organohalide Lead Perovskites: A Key to Suppressed Carrier Recombination in Perovskite Solar Cells?
Dynamical Origin of the Rashba Effect in Organohalide Lead Perovskites: A Key to Suppressed Carrier Recombination in Perovskite Solar Cells?
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DOI：
10.1021/acs.jpclett.6b00564
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发表时间：
2016-05-05
影响因子：
5.7
通讯作者：
De Angelis, Filippo
中科院分区：
文献类型：
--
作者：
Etienne, Thibaud;Mosconi, Edoardo;De Angelis, Filippo
由自旋轨道耦合和反转对称性破坏介导的Rashba带分裂机制的存在已被认为是有机卤化物钙钛矿中观察到的复合率降低的可能原因。在这里，我们调查的电子和核自由度的相互作用，在现实的MAPbI（3）模型中定义的Rashba分裂。我们的模拟揭示了“动态Rashba效应”，允许在热条件下量化其大小。我们发现，即使在全球中心对称的结构的耦合无机-有机自由度的动态引起的空间局部Rashba效应的亚皮秒的时间尺度上波动的典型的甲基铵阳离子动力学。这种效应在全局中心对称结构中逐渐淬灭，可能代表室温下的MAPbl（3）钙钛矿，在将探测的空间尺度增加到32个MAPbl（3）单位（类似于3 nm尺寸）时，因为有机阳离子的无序介导的非相干核热运动。
The presence of a Rashba band-splitting mechanism mediated by spin orbit coupling and breaking of inversion symmetry has been suggested as a possible cause for the reduced recombination rates observed in organohalide perovskites. Here, we investigate the interplay of electronic and nuclear degrees of freedom in defining the Rashba splitting in realistic MAPbI(3) models. Our simulations disclose a "dynamical Rashba effect", allowing for a quantification of its magnitude under thermal conditions. We find that even in globally centrosymmetric structures the dynamics of the coupled inorganic-organic degrees of freedom give rise to a spatially local Rashba effect which fluctuates on the subpico-second time scale typical of the methylammonium cation dynamics. This effect is progressively quenched in globally centrosymmetric structures, likely representing the MAPbl(3) perovskite at room temperature, on increasing the probed spatial scale up to 32 MAPbl(3) units (similar to 3 nm size) because of the incoherent nuclear thermal motion mediated by the disorder of the organic cations.