Dynamical Origin of the Rashba Effect in Organohalide Lead Perovskites: A Key to Suppressed Carrier Recombination in Perovskite Solar Cells?,The Journal of Physical Chemistry Letters

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Dynamical Origin of the Rashba Effect in Organohalide Lead Perovskites: A Key to Suppressed Carrier Recombination in Perovskite Solar Cells?
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2016-04-19 00:00:00 , DOI: 10.1021/acs.jpclett.6b00564
Thibaud Etienne ₁ , Edoardo Mosconi _{1,

2} , Filippo De Angelis _{1,

2}

Affiliation

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 MAPbI₃ 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 subpicosecond time scale typical of the methylammonium cation dynamics. This effect is progressively quenched in globally centrosymmetric structures, likely representing the MAPbI₃ perovskite at room temperature, on increasing the probed spatial scale up to 32 MAPbI₃ units (∼3 nm size) because of the incoherent nuclear thermal motion mediated by the disorder of the organic cations.

中文翻译：

有机卤化物钙钛矿中Rashba效应的动力学起源：钙钛矿太阳能电池中抑制载流子复合的关键吗？

已经有人提出，自旋轨道耦合和反对称对称性破坏介导的拉什巴能带分裂机制的存在可能是导致有机卤化物钙钛矿中复合率降低的可能原因。在这里，我们研究了在定义MAPbI ₃模型中定义Rashba分裂时电子自由度和核自由度之间的相互作用。我们的模拟揭示了“动态Rashba效应””，从而可以量化其在热条件下的大小。我们发现，即使在全局中心对称结构中，无机-有机自由度耦合的动力学也会引起空间局部的Rashba效应，该效应在亚甲基秒阳离子尺度上的亚皮秒时间尺度上波动。这种作用在室温下可能整体上代表MAPbI ₃钙钛矿的整体中心对称结构中逐渐被淬灭，这是由于探针的无序介导的核热运动不连贯，使探测的空间尺度增加到32 MAPbI ₃单位（〜3 nm大小）。有机阳离子。

更新日期：2016-04-19

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