Geometry Distortion and Small Polaron Binding Energy Changes with Ionic Substitution in Halide Perovskites,The Journal of Physical Chemistry Letters

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Geometry Distortion and Small Polaron Binding Energy Changes with Ionic Substitution in Halide Perovskites
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2018-12-07 00:00:00 , DOI: 10.1021/acs.jpclett.8b03343
Amanda J. Neukirch ₁ , Iwnetim I. Abate _{2,

3} , Liujiang Zhou ₁ , Wanyi Nie ₄ , Hsinhan Tsai ₄ , Laurent Pedesseau ₅ , Jacky Even ₅ , Jared J. Crochet ₆ , Aditya D. Mohite ₇ , Claudine Katan ₈ , Sergei Tretiak ₁

Affiliation

Halide perovskites have demonstrated remarkable performance in optoelectronic applications. Despite extraordinary progress, questions remain about device stability. We report an in-depth computational study of small polaron formation, electronic structure, charge density, and reorganization energies of several experimentally relevant halide perovskites using isolated clusters. Local lattice symmetry, electronic structure, and electron–phonon coupling are interrelated in polaron formation in these materials. To illustrate this, first-principles calculations are performed on (MA/Cs/FA)Pb(I/Br)₃ and MASnI₃. Across the materials studied, electron small polaron formation is manifested by Jahn–Teller-like distortions in the central octahedron, with apical PbI bonds expanding significantly more than the equatorial bonds. In contrast, hole polarons cause the central octahedron to uniformly contract. This difference in manifestation of electron and hole polaron formation can be a tool to determine what is taking place in individual systems to systematically control performance. Other trends as the anion and cations are changed are established for optimization in specific optoelectronic applications.

中文翻译：

卤化物钙钛矿中离子的几何变形和小极化子结合能的变化

卤化物钙钛矿在光电应用中已显示出卓越的性能。尽管取得了非凡的进步，但有关设备稳定性的问题仍然存在。我们报告了深入的计算研究，这些极化子的形成，电子结构，电荷密度和几种实验相关卤化物钙钛矿的重组能均采用孤立的簇。这些材料的极化子形成过程中，局部晶格对称性，电子结构和电子-声子耦合相互关联。为了说明这一点，对（MA / Cs / FA）Pb（I / Br）₃和MASnI ₃进行了第一性原理计算。在研究的所有材料中，中心八面体中的Jahn–Teller形畸变证明了电子小极化子的形成，其顶部的PbI键比赤道键扩展得更多。相反，孔极化子使中央八面体均匀收缩。电子和空穴极化子形成表现形式的这种差异可能是确定单个系统中发生的事情以系统地控制性能的一种工具。建立了随着阴离子和阳离子的变化而变化的其他趋势，以便在特定的光电应用中进行优化。

更新日期：2018-12-07

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