Photo-induced macro/mesoscopic scale ion displacement in mixed-halide perovskites : ring structures and ionic plasma oscillations

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Zhang, Y. (Y. ), Sun, X., & Ge, W. (2022). Photo-induced macro/mesoscopic scale ion displacement in mixed-halide perovskites : ring structures and ionic plasma oscillations. Light: Science And Applications. https://doi.org/doi:10.1038/s41377-022-00957-8
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Faculty, Contrary to the common belief that the light-induced halide ion segregation in a mixed halide alloy occurs within the illuminated area, we find that the Br ions released by light are expelled from the illuminated area, which generates a macro/mesoscopic size anion ring surrounding the illuminated area, exhibiting a photoluminescence ring. This intriguing phenomenon can be explained as resulting from two counter-balancing effects: the outward diffusion of the light-induced free Br ions and the Coulombic force between the anion deficit and surplus region. Right after removing the illumination, the macro/mesoscopic scale ion displacement results in a built-in voltage of about 0.4 V between the ring and the center. Then, the displaced anions return to the illuminated area, and the restoring force leads to a damped ultra-low-frequency oscillatory ion motion, with a period of about 20-30 h and lasting over 100 h. This finding may be the first observation of an ionic plasma oscillation in solids. Our understanding and controlling the ion segregation demonstrate that it is possible to turn this commonly viewed adverse phenomenon into novel electronic applications, such as ionic patterning, self-destructive memory, and energy storage.

Details
Title

Photo-induced macro/mesoscopic scale ion displacement in mixed-halide perovskites : ring structures and ionic plasma oscillations

Author(s)

Zhang, Y. (Yong), 1960-
Sun, Xiaoxiao
Ge, Weikun

UNC Charlotte Affiliate Type

Faculty

Extent

1 online resource

Date Created

2022

Genre

articles

Resource Type

text

Abstract

Contrary to the common belief that the light-induced halide ion segregation in a mixed halide alloy occurs within the illuminated area, we find that the Br ions released by light are expelled from the illuminated area, which generates a macro/mesoscopic size anion ring surrounding the illuminated area, exhibiting a photoluminescence ring. This intriguing phenomenon can be explained as resulting from two counter-balancing effects: the outward diffusion of the light-induced free Br ions and the Coulombic force between the anion deficit and surplus region. Right after removing the illumination, the macro/mesoscopic scale ion displacement results in a built-in voltage of about 0.4 V between the ring and the center. Then, the displaced anions return to the illuminated area, and the restoring force leads to a damped ultra-low-frequency oscillatory ion motion, with a period of about 20-30 h and lasting over 100 h. This finding may be the first observation of an ionic plasma oscillation in solids. Our understanding and controlling the ion segregation demonstrate that it is possible to turn this commonly viewed adverse phenomenon into novel electronic applications, such as ionic patterning, self-destructive memory, and energy storage.

Subjects--Topics

Ions
Physics

Is Part Of

Light: science and applications

Language

English

Published Version (Please cite this version)

doi:10.1038/s41377-022-00957-8

Publisher's Version

https://doi.org/10.1038/s41377-022-00957-8

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