Atomic-scale microstructure of metal halide perovskite

Hybrid organic-inorganic perovskites have high potential as materials for solar energy applications, but their microscopic properties are still not well understood. Atomic-resolution scanning transmission electron microscopy has provided invaluable insights for many crystalline solar cell materials, and we used this method to successfully image formamidinium lead triiodide [CH(NH2)2PbI3] thin films with a low dose of electron irradiation. Such images reveal a highly ordered atomic arrangement of sharp grain boundaries and coherent perovskite/PbI2 interfaces, with a striking absence of long-range disorder in the crystal. We found that beam-induced degradation of the perovskite leads to an initial loss of formamidinium [CH(NH2)2+] ions, leaving behind a partially unoccupied perovskite lattice, which explains the unusual regenerative properties of these materials. We further observed aligned point defects and climb-dissociated dislocations. Our findings thus provide an atomic-level understanding of technologically important lead halide perovskites.

Source: ScienceNOW - October 29, 2020 Category: Science Authors: Rothmann, M. U., Kim, J. S., Borchert, J., Lohmann, K. B., OLeary, C. M., Sheader, A. A., Clark, L., Snaith, H. J., Johnston, M. B., Nellist, P. D., Herz, L. M. Tags: Materials Science, Online Only, Physics r-articles Source Type: news