Yu Zhi-Gang
ISP/Applied Sciences Laboratory, Washington State University , Spokane, Washington 99210, United States.
J Phys Chem Lett. 2016 Aug 18;7(16):3078-83. doi: 10.1021/acs.jpclett.6b01404. Epub 2016 Jul 28.
The outstanding photovoltaic performance in hybrid organic-inorganic perovskites (HOIPs) relies on their desirable carrier transport properties. In the HOIPs, strong spin-orbit coupling (SOC) and structural inversion asymmetry give rise to a giant spin splitting in the conduction and valence bands, that is, the Rashba effect (RE), a subject intensively studied in spintronics. Here we show that this giant RE can manifest itself in charge transport and is the key to understanding carrier mobility and its temperature dependence in the HOIPs. The RE greatly enhances acoustic-phonon scattering (APS) and alters the temperature dependence of carrier mobility from T(-3/2) to T(-1). Meanwhile, it reduces polar-optical phonon scattering (POPS). In CH3NH3PbI3, the carrier mobility is limited by the APS for temperatures up to 100 K, above which the POPS becomes dominant. The effective polar coupling is moderate, α = 1.1, indicating that band conduction is still a valid description of charge transport. Our results account for the observed carrier transport behaviors over the entire temperature range and highlight the importance of SOC in charge transport in the HOIPs.
有机-无机杂化钙钛矿（HOIPs）出色的光伏性能依赖于其理想的载流子传输特性。在HOIPs中，强自旋-轨道耦合（SOC）和结构反演不对称导致导带和价带中出现巨大的自旋分裂，即Rashba效应（RE），这是自旋电子学中深入研究的一个课题。在此我们表明，这种巨大的RE可在电荷传输中表现出来，并且是理解HOIPs中载流子迁移率及其温度依赖性的关键。RE极大地增强了声学声子散射（APS），并将载流子迁移率的温度依赖性从T^(-3/2)改变为T^(-1)。同时，它减少了极性光学声子散射（POPS）。在CH3NH3PbI3中，对于高达100 K的温度，载流子迁移率受APS限制，高于此温度POPS占主导。有效极性耦合适中，α = 1.1，表明能带传导仍是电荷传输的有效描述。我们的结果解释了在整个温度范围内观察到的载流子传输行为，并突出了SOC在HOIPs电荷传输中的重要性。
