Large Polaron Self-Trapped States in Three-Dimensional Metal-Halide Perovskites,ACS Materials Letters

当前位置： X-MOL 学术 › ACS Mater. Lett. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Large Polaron Self-Trapped States in Three-Dimensional Metal-Halide Perovskites
ACS Materials Letters ( IF 9.6 ) Pub Date : 2019-11-22 , DOI: 10.1021/acsmaterialslett.9b00276
Walter P. D. Wong ₁ , Jun Yin ₂ , Bhumika Chaudhary _{3,

4} , Xin Yu Chin ₄ , Daniele Cortecchia _{3,

4} , Shu-Zee A. Lo ₅ , Andrew C. Grimsdale ₁ , Omar F. Mohammed ₂ , Guglielmo Lanzani _{4,

6,

7} , Cesare Soci _{4,

5}

Affiliation

In recent years, metal halide perovskites have generated tremendous interest for optoelectronic applications and their underlying fundamental properties. Because of the large electron-phonon coupling characteristic of soft lattices, self-trapping phenomena are expected to dominate hybrid perovskite photoexcitation dynamics. Yet, while the photogeneration of small polarons was proven in low-dimensional perovskites, the nature of polaron excitations in technologically relevant 3D perovskites, and their influence on charge carrier transport, remain elusive. In this study, we used a combination of first principle calculations and advanced spectroscopy techniques spanning the entire optical frequency range to pin down polaron features in three-dimensional metal halide perovskites. Mid-infrared photoinduced absorption shows the photogeneration of states associated with low energy intragap electronic transitions with lifetime up to the millisecond time scale, and vibrational mode renormalization in both frequency and amplitude. Density functional theory supports the assignment of the spectroscopic features to large polarons leading to new intragap transitions, hardening of phonon mode frequency, and renormalization of the oscillator strength. Theory provides quantitative estimation for the charge carrier masses and mobilities increase upon polaron formation, confirming experimental results. Overall, this work contributes to complete the scenario of elementary photoexcitations in metal halide perovskites and highlights the importance of polaronic transport in perovskite-based optoelectronic devices.

中文翻译：

三维金属卤化物钙钛矿中的大极化子自陷状态

近年来，金属卤化物钙钛矿对光电应用及其潜在的基本性能引起了极大的兴趣。由于软晶格具有大的电子-声子耦合特性，自陷现象有望主导混合钙钛矿光激发动力学。然而，尽管在低维钙钛矿中已证明了小极化子的光生作用，但在技术上相关的3D钙钛矿中极化子激发的性质及其对电荷载流子传输的影响仍然难以捉摸。在这项研究中，我们结合了第一原理计算和先进的光谱技术，将技术应用于整个光学频率范围，以固定三维金属卤化物钙钛矿中的极化子特征。中红外光诱导的吸收显示出与低能隙内电子跃迁相关的状态的光生，其寿命长达毫秒时间尺度，并且在频率和振幅方面都实现了振动模式的重新归一化。密度泛函理论支持将光谱特征分配给大极化子，从而导致新的带隙跃迁，声子模频率变硬以及振荡器强度重新归一化。理论提供了对极化子形成时载流子质量和迁移率增加的定量估计，从而证实了实验结果。总体而言，这项工作有助于完成金属卤化物钙钛矿中基本光激发的场景，并突出了基于钙钛矿的光电器件中极化子传输的重要性。

更新日期：2019-11-22

点击分享查看原文

点击收藏

公开下载

阅读更多本刊最新论文本刊介绍/投稿指南11