Critical Role of Methylammonium Librational Motion in Methylammonium Lead Iodide (CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>) Perovskite Photochemistry.
basic_science · Level V
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- Record sourced from PubMed, PMID 28562052.
- Also identified by DOI 10.1021/acs.nanolett.7b00919.
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Abstract
Raman and photoluminescence (PL) spectroscopy are used to investigate dynamic structure-function relationships in methylammonium lead iodide (MAPbI<sub>3</sub>) perovskite. The intensity of the 150 cm<sup>-1</sup> methylammonium (MA) librational Raman mode is found to be correlated with PL intensities in microstructures of MAPbI<sub>3</sub>. Because of the strong hydrogen bond between hydrogens in MA and iodine in the PbI<sub>6</sub> perovskite octahedra, the Raman activity of MA is very sensitive to structural distortions of the inorganic framework. The structural distortions directly influence PL intensities, which in turn have been correlated with microstructure quality. Our measurements, supported with first-principles calculations, indicate how excited-state MA librational displacements mechanistically control PL efficiency and lifetime in MAPbI<sub>3</sub>-material parameters that are likely important for efficient photovoltaic devices.