Atomic-Scale Polarization and Strain at the Surface of Lead Halide Perovskite Nanocrystals.

Abstract
Inorganic halide perovskite nanocrystals (NCs) are being widely explored as next-generation optoelectronic materials. Critical to understanding the optoelectronic properties and stability behavior of perovskite NCs is the material’s surface structure, where the local atomic configuration deviates from that of the bulk. Through low-dose aberration-corrected scanning transmission electron microscopy and quantitative imaging analysis techniques, we directly observed the atomic structure at the surface of the CsPbBr3 NCs. CsPbBr3 NCs are terminated by a Cs–Br plane, and the surface Cs–Cs bond length decreases significantly (∼5.6%) relative to the bulk, imposing compressive strain and inducing polarization, which we also observed in CsPbI3 NCs. Density functional theory calculations suggest such a reconstructed surface contributes to the separation of holes and electrons. These findings enhance our fundamental understanding of the atomic-scale structure, strain, and polarity at the surface of inorganic halide perovskites and provide valuable insights into designing stable and efficient optoelectronic devices.

Citation
Chen, S., Wang, J., Thomas, S., Mir, W. J., Shao, B., Lu, J., Wang, Q., Gao, P., Mohammed, O. F., Han, Y., & Bakr, O. M. (2023). Atomic-Scale Polarization and Strain at the Surface of Lead Halide Perovskite Nanocrystals. Nano Letters. https://doi.org/10.1021/acs.nanolett.3c01189

Acknowledgements
This work was supported by King Abdullah University of Science and Technology (KAUST). We also acknowledge the support of Prof. Qing Zhang in Peking University for providing CsPbCl3 samples.

Journal
Nano letters

DOI
10.1021/acs.nanolett.3c01189

PubMed ID
37342001

Additional Links
https://pubs.acs.org/doi/10.1021/acs.nanolett.3c01189

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