The localization of photogenerated electrons in photovoltaic and photocatalytic materials is crucial for reducing the electron–hole recombination rate. Here, the photogenerated electron localization is systematically investigated on the CH3NH3PbI3 (MAPbI3) perovskite using first-principles calculations. It is found that under vacuum conditions, the photogenerated electron is delocalized in the MAPbI3 bulk as well as on the stochiometric MAPbI3(001) surface with the CH3NH3I (MAI) termination, while it is trapped on the defect-free PbI2-terminated surface. Our ab initio molecular dynamics simulations reveal that the introduction of solutions will prompt the formation of localized electronic states. The photogenerated electron is discovered to be localized on both the MAI- and PbI2-terminated surfaces in the presence of solutions with different concentrations of HI, from pure water to the saturated solution. We demonstrate that the Pb–I bond weakening or breaking resulting in an unsaturated coordination of a Pb site is the prerequisite to trap the photogenerated electron.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the UK’s national high performance computing service ARCHER, THOMAS, and QUB high performance computing centre for computing resources. Y.D. thanks the Queen’s University Belfast and China Scholarship Council for the Ph.D. studentship. C.P. thanks the National Science Foundation of Hunan Province (2019JJ50526).
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ASJC Scopus subject areas
- Materials Science(all)
- Physical and Theoretical Chemistry