Influence of water intercalation and hydration on chemical decomposition and ion transport in methylammonium lead halide perovskites
Influence of water intercalation and hydration on chemical decomposition and ion transport in methylammonium lead halide perovskites
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DOI：
10.1039/c7ta09112e
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发表时间：
2018-01-21
影响因子：
11.9
通讯作者：
Walsh, Aron
中科院分区：
文献类型：
--
作者：
Jong, Un-Gi;Yu, Chol-Jun;Walsh, Aron
近年来，甲基铵（MA）卤化铅钙钛矿（CH_3NH_3PbX_3（X = I，Br，Cl））在钙钛矿太阳能电池中的应用在性能效率方面取得了很大进展。然而，这些材料在潮湿环境中的快速分解阻碍了户外应用，因此，需要全面了解降解机理。利用第一性原理计算研究了CH3NH3PbX3的水嵌入和水化对分解和离子迁移的影响。结果表明，水与PbX6和MA之间通过氢键相互作用，从X = I到Br和Cl，水与PbX6和MA之间的氢键作用逐渐增强，而MA与PbX6之间的氢键作用几乎没有变化.热力学计算表明，水嵌入到钙钛矿，并建议，水插层和一水合化合物是稳定的分解。更重要的是，水嵌入降低了空位介导的离子迁移的活化能，其从X = I到Br和Cl变得更高。我们的工作表明，必须避免卤化物钙钛矿的水合作用，以防止太阳能电池在水分暴露时的退化。
The application of methylammonium (MA) lead halide perovskites, CH3NH3PbX3 (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 CH3NH3PbX3 using first-principles calculations. We find that water interacts with PbX6 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.