实验发现,纳米结构可以改变晶体优先对称性从正交相变为高对称的立方相,受此启发,该研究组使用从头算量子动力学模拟,研究了CsPbBr3在不同多态相中的载流子动力学。课题组人员发现立方相的非弹性声子散射比正交相的小;八面体倾斜的抑制使纵向Br波动最小化,并有助于从非绝热载流子动力学中解耦A-位阳离子动力学。他们的工作将提供一种材料设计原则,通过对称工程提高卤化物钙钛矿量子点的量子产率,这将有助于开发基于卤化物钙钛矿量子点的高发光LED技术。
研究人员表示,金属卤化物钙钛矿作为光电子器件中的活性材料受到了广泛的关注。对于发光二极管(LED)的应用,纳米结构的卤化物钙钛矿被认为是不可避免的,但由于粒子(或颗粒)的尺寸往往超出量子效应的尺度,其光增强机制仍不明确。
附:英文原文
Title: Enhanced Light Emission through Symmetry Engineering of Halide Perovskites
Author: Yoonhoo Ha, Jong-Goo Park, Ki-Ha Hong, Hyungjun Kim
Issue&Volume: December 27, 2021
Abstract: Metal-halide perovskites (MHPs) have attracted tremendous attention as active materials in optoelectronic devices. For light-emitting diode (LED) applications, nanostructuring of MHPs is considered to be inevitable, but its light-enhancement mechanism is still elusive because the particle (or grain) size is often beyond the quantum confinement regime. As motivated by the experimental finding that the nanostructuring can change the preferred crystalline symmetry from the orthorhombic phase to the high-symmetric cubic phase, we here investigated the carrier dynamics in various polymorphic phases of CsPbBr3 using ab initio quantum dynamics simulation. We found that the cubic phase shows a smaller inelastic phonon scattering than the orthorhombic phase; the suppression of the octahedral tilt minimizes the longitudinal Br fluctuation and helps disentangle the A-site cation dynamics from the nonadiabatic carrier dynamics. We thus anticipate that our present work will offer a material design principle to enhance the quantum yield of MHPs via symmetry engineering, which will help develop highly luminescent LED technology based on MHPs.
DOI: 10.1021/jacs.1c09891
Source: https://pubs.acs.org/doi/10.1021/jacs.1c09891
JACS:《美国化学会志》,创刊于1879年。隶属于美国化学会,最新IF:14.612
官方网址:https://pubs.acs.org/journal/jacsat
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