Halogen Migration in Hybrid Perovskites: The Organic Cation Matters

Aleksandra Oranskaia, Jun Yin, Osman M. Bakr, Jean Luc Brédas, Omar F. Mohammed*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

114 Scopus citations


In hybrid perovskite materials, the organic cations are one of the key structural components used to tune the electronic and optical properties of this promising class of materials. Here, we studied the strong impact of organic cations, methylammonium (MA) and formamidinium (FA), on halogen vacancy and interstitial migration, as well as surface degradation in cubic-phase MAPbBr3 and FAPbBr3 crystals using density functional theory calculations. We found Br vacancies and interstitials have much lower formation energies and higher density in MAPbBr3 in comparison to FAPbBr3 crystals. Moreover, the transition energy barrier for Br migration through vacancies within the bulk phase is lower in MAPbBr3 than in FAPbBr3. We also found that FAPbBr3 has a much higher rotation barrier of the organic cation than MAPbBr3, which points to a much stronger H-bonding with Br in the former case. Our results show that incorporating organic cations with the appropriate structure, shape, and strong H-bonding capabilities in hybrid perovskite crystals is very beneficial for suppressing ion migration and thus further improving the performance of hybrid perovskite-based devices.

Original languageEnglish (US)
Pages (from-to)5474-5480
Number of pages7
JournalJournal of Physical Chemistry Letters
Issue number18
StatePublished - Sep 20 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry


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