Revealing nanomechanical domains and their transient behavior in mixed‐halide perovskite films

DOI: 10.1002/adfm.202100293

Authors: Ioanna Mela (University of Cambridge) , Chetan Poudel (University of Cambridge) , Miguel Anaya (University of Cambridge) , Geraud Delport (University of Cambridge) , Kyle Frohna (University of Cambridge) , Stuart Macpherson (University of Cambridge) , Tiarnan A. S. Doherty (University of Cambridge) , Anna Scheeder (University of Cambridge) , Samuel D. Stranks (University of Cambridge) , Clemens F. Kaminski (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Advanced Functional Materials

State: Published (Approved)
Published: March 2021
Diamond Proposal Number(s): 20420

Abstract: Halide 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.

Journal Keywords: halide perovskites; multimodal imaging; nanomechanical mapping; nanoscale heterogeneities; polycrystalline thin films

Diamond Keywords: Semiconductors; Photovoltaics; Light‐Emitting Diodes (LEDs)

Subject Areas: Materials, Chemistry, Energy


Instruments: I14-Hard X-ray Nanoprobe

Documents:
adfm.202100293.pdf

Discipline Tags:

Material Sciences Energy Materials Metallurgy Perovskites Physics Surfaces interfaces and thin films

Technical Tags:

Imaging X-ray Fluorescence (XRF)