Determining Atomic-Scale Structure and Composition of Organo-Lead Halide Perovskites by Combining High-Resolution X-ray Absorption Spectroscopy and First-Principles Calculations

Walter S. Drisdell*, Linn Leppert, Carolin M. Sutter-Fella, Yufeng Liang, Yanbo Li, Quynh P. Ngo, Liwen F. Wan, Sheraz Gul, Thomas Kroll, Dimosthenis Sokaras, Ali Javey, Junko Yano, Jeffrey B. Neaton, Francesca M. Toma, David Prendergast, Ian D. Sharp

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

Abstract

We combine high-energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy (XAS) measurements with first-principles density functional theory (DFT) calculations to provide a molecular-scale understanding of local structure, and its role in defining optoelectronic properties, in CH3NH3Pb(I1-xBrx)3 perovskites. The spectra probe a ligand field splitting in the unoccupied d states of the material, which lie well above the conduction band minimum and display high sensitivity to halide identity, Pb-halide bond length, and Pb-halide octahedral tilting, especially for apical halide sites. The spectra are also sensitive to the organic cation. We find that the halides in these mixed compositions are randomly distributed, rather than having preferred octahedral sites, and that thermal tilting motions dominate over any preferred structural distortions as a function of halide composition. These findings demonstrate the utility of the combined HERFD XAS and DFT approach for determining structural details in these materials and connecting them to optoelectronic properties observed by other characterization methods.

Original languageEnglish
Pages (from-to)1183-1189
Number of pages7
JournalACS Energy Letters
Volume2
Issue number5
DOIs
Publication statusPublished - 12 May 2017
Externally publishedYes

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