Dynamic emission Stokes shift and liquid-like dielectric solvation of band edge carriers in lead-halide perovskites
Dynamic emission Stokes shift and liquid-like dielectric solvation of band edge carriers in lead-halide perovskites
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DOI：
10.1038/s41467-019-09057-5
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发表时间：
2019-03-12
影响因子：
16.6
通讯作者：
Brus, Louis E.
中科院分区：
文献类型：
--
作者：
Guo, Yinsheng;Yaffe, Omer;Brus, Louis E.
卤化铅钙钛矿已成为光伏和光电应用的有前途的材料。与传统的谐波半导体相比，它们的显着非谐晶格运动在理解其特殊光电特性的起源方面提出了概念上的挑战。在这里，我们报告了一个强烈的温度依赖性发光斯托克斯位移的电子光谱的混合和无机铅溴化钙钛矿单晶。这种行为与更传统的晶体半导体所表现出的行为形成鲜明对比。我们关联了电子光谱与反斯托克斯和斯托克斯拉曼振动光谱。介电溶剂化理论，最初开发的激发分子溶解在极性液体中，重现我们的实验观察。我们的方法，它调用了一个经典的德拜样弛豫过程，捕获的介电响应起源于约20 meV（160 cm（-1））的铅溴框架中的LO声子的初始非谐性。我们调和这个类液体模型，将热激活介电溶剂化与更标准的固态理论的发射斯托克斯位移在晶体半导体。
Lead-halide perovskites have emerged as promising materials for photovoltaic and optoelectronic applications. Their significantly anharmonic lattice motion, in contrast to conventional harmonic semiconductors, presents a conceptual challenge in understanding the genesis of their exceptional optoelectronic properties. Here we report a strongly temperature dependent luminescence Stokes shift in the electronic spectra of both hybrid and inorganic lead-bromide perovskite single crystals. This behavior stands in stark contrast to that exhibited by more conventional crystalline semiconductors. We correlate the electronic spectra with the anti-Stokes and Stokes Raman vibrational spectra. Dielectric solvation theories, originally developed for excited molecules dissolved in polar liquids, reproduce our experimental observations. Our approach, which invokes a classical Debye-like relaxation process, captures the dielectric response originating from the incipient anharmonicity of the LO phonon at about 20 meV (160 cm(-1)) in the lead-bromide framework. We reconcile this liquid-like model incorporating thermally-activated dielectric solvation with more standard solid-state theories of the emission Stokes shift in crystalline semiconductors.