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

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Title: Influence of water intercalation and hydration on chemical decomposition and ion transport in methylammonium lead halide perovskites
Authors: Jong, U-G
Yu, C-J
Ri, G-C
McMahon, AP
Harrison, NM
Barnes, PRF
Walsh, A
Item Type: Working Paper
Abstract: The use of methylammonium (MA) lead halide perovskites \ce{CH3NH3PbX3} (X=I, Br, Cl) in perovskite solar cells (PSCs) has made great progress in performance efficiency during recent years. However, the rapid decomposition of \ce{MAPbI3} in humid environments hinders outdoor application of PSCs, and thus, a comprehensive understanding of the degradation mechanism is required. To do this, we investigate the effect of water intercalation and hydration of the decomposition and ion migration of \ce{CH3NH3PbX3} using first-principles calculations. We find that water interacts with \ce{PbX6} and MA through hydrogen bonding, and the former interaction enhances 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, while the water intercalated and monohydrated compounds are stable with respect to decomposition. More importantly, the water intercalation greatly 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 PSCs upon moisture exposure.
Issue Date: 21-Jan-2018
URI: http://hdl.handle.net/10044/1/54203
Copyright Statement: © 2017 The Author(s)
Sponsor/Funder: Royal Institution of Great Britain
Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: GR/S13422/01
EP/P023118/1
Keywords: cond-mat.mtrl-sci
Appears in Collections:Faculty of Engineering
Materials
Chemistry
Faculty of Natural Sciences



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