Polarized Raman Study of Internal Vibrations of the Organic Cation in 3-Cyanopyridinium Lead Tribromide Post-perovskite

In this work, we apply polarized Raman spectroscopy for study of internal vibrations of the 3-cyanopyridinium cation in the halide post-perovskite (3cp)PbBr3 (3cp = 3CN-C5H5NH+). For a single cation, the vibrational frequencies and intensities of the Raman signal were calculated using the density functional theory. Selection rules were established for vibrations of cations in the crystal. These rules together with modeling results were used to identify the internal vibrations of the cation in the Raman spectrum of the crystal. Narrow and isolated internal vibrations of cations could be used as spectators of the crystalline environment.

Automated summary

In this study, polarized Raman spectroscopy was used to investigate the internal vibrations of the 3-cyanopyridinium cation in the halide post-perovskite (3cp)PbBr3 crystal. The vibrational frequencies and intensities of the Raman signal were calculated for a single cation using density functional theory. Selection rules for cation vibrations in the crystal were established and used to identify the internal vibrations of the cation in the Raman spectrum. Narrow and isolated internal cation vibrations can serve as indicators of the crystalline environment.