Thermodynamic Origin of the Photostability of the Two-Dimensional Perovskite PEA2Pb(I1-xBrx)4

Zehua Chen, Haibo Xue, Geert Brocks, Peter A. Bobbert*, Shuxia Tao

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)
36 Downloads (Pure)


The two-dimensional (2D) mixed halide perovskite PEA2Pb(I1-xBrx)4 exhibits high phase stability under illumination as compared to the three-dimensional (3D) counterpart MAPb(I1-xBrx)3. We explain this difference using a thermodynamic theory that considers the sum of a compositional and a photocarrier free energy. Ab initio calculations show that the improved compositional phase stability of the 2D perovskite is caused by a preferred I-Br distribution, leading to a much lower critical temperature for halide segregation in the dark than for the 3D perovskite. Moreover, a smaller increase of the band gap with Br concentration x and a markedly shorter photocarrier lifetime in the 2D perovskite reduce the driving force for phase segregation under illumination, enhancing the photostability.

Original languageEnglish
Pages (from-to)943-949
Number of pages7
JournalACS Energy Letters
Issue number2
Early online date12 Jan 2023
Publication statusPublished - 10 Feb 2023


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