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Revealing Nanomechanical Domains and Their Transient Behavior in Mixed-Halide Perovskite Films

Published version
Peer-reviewed

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Abstract

jats:titleAbstract</jats:title>jats:pHalide perovskites are a versatile class of semiconductors employed for high performance emerging optoelectronic devices, including flexoelectric systems, yet the influence of their ionic nature on their mechanical behavior is still to be understood. Here, a combination of atomic‐force, optical, and compositional X‐ray microscopy techniques is employed to shed light on the mechanical properties of halide perovskite films at the nanoscale. Mechanical domains within and between morphological grains, enclosed by mechanical boundaries of higher Young's Modulus (YM) than the bulk parent material, are revealed. These mechanical boundaries are associated with the presence of bromide‐rich clusters as visualized by nano‐X‐ray fluorescence mapping. Stiffer regions are specifically selectively modified upon light soaking the sample, resulting in an overall homogenization of the mechanical properties toward the bulk YM. This behavior is attributed to light‐induced ion migration processes that homogenize the local chemical distribution, which is accompanied by photobrightening of the photoluminescence within the same region. This work highlights critical links between mechanical, chemical, and optoelectronic characteristics in this family of perovskites, and demonstrates the potential of combinational imaging studies to understand and design halide perovskite films for emerging applications such as photoflexoelectricity.</jats:p>

Description

Keywords

halide perovskites, multimodal imaging, nanomechanical mapping, nanoscale heterogeneities, polycrystalline thin films

Journal Title

Advanced Functional Materials

Conference Name

Journal ISSN

1616-301X
1616-3028

Volume Title

31

Publisher

Wiley
Sponsorship
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (722380)
Royal Society (UF150033)
European Research Council (756962)
Engineering and Physical Sciences Research Council (EP/R023980/1)
Royal Society (NF170533)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (841386)
Engineering and Physical Sciences Research Council (EP/H018301/1)
Wellcome Trust (089703/Z/09/Z)
Medical Research Council (MR/K015850/1)
Medical Research Council (MR/K02292X/1)
Engineering and Physical Sciences Research Council (EP/L015889/1)
Engineering and Physical Sciences Research Council (EP/S022953/1)
EPSRC (2127077)