Electron-Phonon Scattering in Atomically Thin 2D Perovskites
Electron-Phonon Scattering in Atomically Thin 2D Perovskites
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DOI：
10.1021/acsnano.6b04265
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发表时间：
2016-11-01
期刊：
影响因子：
17.1
通讯作者：
Huang, Libai
中科院分区：
文献类型：
--
作者：
Guo, Zhi;Wu, Xiaoxi;Huang, Libai
具有强束缚激子的二维（2D）原子薄钙钛矿在光电应用中具有很高的前景。然而，限制光致发光（PL）效率的非辐射过程的性质仍然难以捉摸。在这里，我们提出了时间分辨和温度相关的PL研究，系统地解决本征激子弛豫路径的层状（C4 H9 NH3）（2）（CH 3 NH3）（n-1）PbnI 3 n +1（n = 1，2，3）结构。我们的研究结果表明，通过变形势的声学和同极光学声子的散射是主要的散射机制的激子在单剥离薄片，表现出T-γ（γ = 1.3至1.9）的温度依赖性的散射率。我们将极性光学声子和缺陷散射的缺乏归因于库仑势的有效屏蔽，类似于在3D钙钛矿中观察到的。这些结果建立了理解的起源非辐射途径，并提供指导方针优化PL效率的原子薄的二维钙钛矿。
Two-dimensional (2D) atomically thin perovskites with strongly bound excitons are highly promising for optoelectronic applications. However, the nature of nonradiative processes that limit the photoluminescence (PL) efficiency remains elusive. Here, we present time resolved and temperature-dependent PL studies to systematically address the intrinsic exciton relaxation pathways in layered (C4H9NH3)(2)(CH3NH3)(n-1)PbnI3n+1 (n = 1, 2, 3) structures. Our results show that scatterings via deformation potential by acoustic and homopolar optical phonons are the main scattering mechanisms for excitons in ultrathin single exfoliated flakes, exhibiting a T-gamma (gamma = 1.3 to 1.9) temperature dependence for scattering rates. We attribute the absence of polar optical phonon and defect scattering to efficient screening of Coulomb potential, similar to what has been observed in 3D perovskites. These results establish an understanding of the origins of nonradiative pathways and provide guidelines for optimizing PL efficiencies of atomically thin 2D perovskites.