Influence of water intercalation and hydration on chemical decomposition and ion transport in methylammonium lead halide perovskites

Un Gi Jong, Chol Jun Yu, Gum Chol Ri, Andrew P. McMahon, Nicholas M. Harrison, Piers R.F. Barnes, Aron Walsh

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The application of methylammonium (MA) lead halide perovskites, CH 3 NH 3 PbX 3 (X = I, Br, Cl), in perovskite solar cells has made great recent progress in performance efficiency during recent years. However, the rapid decomposition of these materials in humid environments hinders outdoor application, and thus, a comprehensive understanding of the degradation mechanism is required. We investigate the effect of water intercalation and hydration of the decomposition and ion migration of CH 3 NH 3 PbX 3 using first-principles calculations. We find that water interacts with PbX 6 and MA through hydrogen bonding, and the former interaction increases gradually, while the latter hardly changes when going from X = I to Br and to Cl. Thermodynamic calculations indicate that water exothermically intercalates into the perovskite, and suggest that the water intercalated and monohydrated compounds are stable with respect to decomposition. More importantly, the water intercalation reduces the activation energies for vacancy-mediated ion migration, which become higher going from X = I to Br and to Cl. Our work indicates that hydration of halide perovskites must be avoided to prevent the degradation of solar cells upon moisture exposure.

Original languageEnglish
Pages (from-to)1067-1074
Number of pages8
JournalJournal of Materials Chemistry A
Volume6
Issue number3
DOIs
Publication statusPublished - 2018 Jan 1

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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