Pressure Regulating Self‐Trapped States toward Remarkable Emission Enhancement of Zero‐Dimensional Lead‐Free Halides Nanocrystals
Yue Shi, Yuan Fu, Zhiwei Ma, Dianlong Zhao, Kai Wang, Guanjun Xiao, Bo Zou
Abstract
Abstract Copper(I)‐based halides have recently attracted increasing attention as a substitute for lead halides, owing to their nontoxicity, abundance, unique structure, and optoelectric properties. However, exploring an effective strategy to further improve their optical activities and revealing structure−optical property relationships still remain a great concern. Here, by using high pressure technique, a remarkable enhancement of self‐trapped exciton (STE) emission associated with the energy exchange between multiple self‐trapped states in zero‐dimensional lead‐free halide Cs 3 Cu 2 I 5 NCs is successfully achieved. Furthermore, high‐pressure processing endows the piezochromism of Cs 3 Cu 2 I 5 NCs by experiencing a white light and a strong purple light emission, which is able to be stabilized at near‐ambient pressure. The distortion of [Cu 2 I 5 ] clusters composing of tetrahedral [CuI 4 ] and trigonal planar [CuI 3 ] and the decreased Cu–Cu distance between the adjacent Cu‐I tetrahedron and triangle are responsible for the significant STEs emission enhancement under high pressure. The experiments combined with first‐principles calculations not only shed light on the structure−optical property relationships of [Cu 2 I 5 ] clusters halide, but also provide guidance for improving emission intensity that is highly desirable in solid‐state lighting applications.