Interstitial Occupancy by Extrinsic Alkali Cations in Perovskites and Its Impact on Ion Migration
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AbstractRecent success in achieving highly stable Rb-containing organolead halide perovskites has indicated the possibility of incorporating small monovalent cations, which cannot fit in the lead-halide cage with an appropriate tolerance factor, into the perovskite lattice while maintaining a pure stable "black" phase. In this study, through a combined experimental and theoretical investigation by density functional theory (DFT) calculations on the incorporation of extrinsic alkali cations (Rb+, K+, Na+, and Li+) in perovskite materials, the size-dependent interstitial occupancy of these cations in the perovskite lattice is unambiguously revealed. Interestingly, DFT calculations predict the increased ion migration barriers in the lattice after the interstitial occupancy. To verify this prediction, ion migration behavior is characterized through hysteresis analysis of solar cells, electrical poling, temperature-dependent conductivity, and time-dependent photoluminescence measurements. The results collectively point to the suppression of ion migration after lattice interstitial occupancy by extrinsic alkali cations. The findings of this study provide new material design principles to manipulate the structural and ionic properties of multication perovskite materials.
All Author(s) ListCao J, Tao SX, Bobbert PA, Wong CP, Zhao N
Journal nameAdvanced Materials
Volume Number30
Issue Number26
Article number1707350
LanguagesEnglish-United Kingdom
Keywordsdensity functional theory, interstitial occupancy, ion migration, multication perovskites
Web of Science Subject CategoriesChemistry, Multidisciplinary;Chemistry, Physical;Nanoscience & Nanotechnology;Materials Science, Multidisciplinary;Physics, Applied;Physics, Condensed Matter;Chemistry;Science & Technology - Other Topics;Materials Science;Physics

Last updated on 2020-19-10 at 03:53