Atomic Structure and Electrical Activity of Grain Boundaries and Ruddlesden-Popper Faults in Cesium Lead Bromide Perovskite.

Author(s) Thind, A.Singh; Luo, G.; Hachtel, J.A.; Morrell, M.V.; Cho, S.Beom; Borisevich, A.Y.; Idrobo, J.C.; Xing, Y.; Mishra, R.
Journal Adv Mater
Date Published 2019 Jan

To evaluate the role of planar defects in lead-halide perovskites-cheap, versatile semiconducting materials-it is critical to examine their structure, including defects, at the atomic scale and develop a detailed understanding of their impact on electronic properties. In this study, postsynthesis nanocrystal fusion, aberration-corrected scanning transmission electron microscopy, and first-principles calculations are combined to study the nature of different planar defects formed in CsPbBr nanocrystals. Two types of prevalent planar defects from atomic resolution imaging are observed: previously unreported Br-rich [001](210)∑5 grain boundaries (GBs) and Ruddlesden-Popper (RP) planar faults. The first-principles calculations reveal that neither of these planar faults induce deep defect levels, but their Br-deficient counterparts do. It is found that the ∑5 GB repels electrons and attracts holes, similar to an n-p-n junction, and the RP planar defects repel both electrons and holes, similar to a semiconductor-insulator-semiconductor junction. Finally, the potential applications of these findings and their implications to understand the planar defects in organic-inorganic lead-halide perovskites that have led to solar cells with extremely high photoconversion efficiencies are discussed.

DOI 10.1002/adma.201805047
ISSN 1521-4095
Citation Adv Mater Weinheim. 2019;31(4):e1805047.

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