Exciton–Phonon Coupling of Chiral One-Dimensional Lead-Free Hybrid Metal Halides at Room Temperature
Zhen Li, Yan Yan, Mu‐Sen Song, Jiayu Xin, Hai‐Yu Wang, Hai Wang, Yu Wang
Abstract
The interaction between organic cations and inorganic metal halide octahedral units strongly affects the properties of organic–inorganic hybrid metal halides. The “soft” property of the lattice provides the possibility of its strong exciton–phonon interaction. Here we report one-dimensional (1D) lead-free chiral organic–inorganic hybrid metal halide single crystals of (R/S)-methylbenzylamine bismuth iodide (R/S-MBA)2Bi2I8, which exhibits a high level of octahedral bond distortion. The introduction of chiral amines leads to a strong chiroptical response in the range of 200–600 nm. The strong exciton–phonon coupling can be observed through the coherent oscillation spectrum of transient absorption dynamics at room temperature. The coherent phonon oscillation frequencies are ∼97 and ∼130 cm–1, corresponding to the symmetrical stretching or bending of the Bi–I octahedron. Our work provides new insights for the study of exciton–phonon coupling in 1D chiral hybrid metal halides.