Interstitial occupancy by extrinsic alkali cations in Perovskites and its impact on ion migration

Jie Cao, S. Tao, P.A. Bobbert, Ching-Ping Wong, Ni Zhao

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Recent 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.

Original languageEnglish
Article number1707350
Number of pages9
JournalAdvanced Materials
Issue number26
Publication statusPublished - 27 Jun 2018


  • Density functional theory
  • Interstitial occupancy
  • Ion migration
  • Multication perovskites
  • interstitial occupancy
  • density functional theory
  • ion migration
  • multication perovskites

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