Strong Electron-Phonon Coupling and Lattice Dynamics in One-Dimensional [(CH3)2NH2]PbI3 Hybrid Perovskite

TL;DR

This study explores the strong electron-phonon coupling and lattice dynamics in 1D hybrid perovskite DMAPbI3, revealing how temperature-induced phase transitions influence its optoelectronic properties and photoluminescence behavior.

Contribution

It provides new insights into the electron-phonon interactions and phase transition effects in 1D hybrid perovskites using multiple advanced characterization techniques.

Findings

Reversible structural phase transition affects optoelectronic properties.

Strong electron-phonon coupling leads to self-trapped excitons and color shifts.

Identification of LO phonon mode at 84 cm-1 as key in electron-phonon interaction.

Abstract

Hybrid halide perovskites (HHPs) have attracted significant attention due to their remarkable optoelectronic properties that combine the advantages of low cost-effective fabrication methods of organic-inorganic materials. Notably, low-dimensional hybrid halide perovskites including two-dimensional (2D) layers and one-dimensional (1D) chains, are recognized for their superior stability and moisture resistance, making them highly appealing for practical applications. Particularly, DMAPbI3 has attracted attention due to other interesting behaviors and properties, such as thermally induced order-disorder processes, dielectric transition, and cooperative electric ordering of DMA dipole moments. In this paper, we investigated the interplay between low-temperature SPT undergone by the low-dimensional (1D) hybrid halide perovskite-like material DMAPbI3 and its optoelectronic properties. Our approach combines synchrotron X-ray powder diffraction, Raman spectroscopy, thermo-microscopy, differential scanning calorimetry (DSC), and photoluminescence (PL) techniques. Temperature-dependent Synchrotron powder diffraction and Raman Spectroscopy reveal that the modes associated with I-Pb-I and DMA+ ion play a crucial role in the order-disorder SPT in DMAPbI3. The reversible SPT modifies its optoelectronic properties, notably affecting its thermochromic behavior and PL emission. The origin of the PL phenomenon is associated to self-trapped excitons (STEs), which are allowed due to a strong electron-phonon coupling quantified by the Huang-Rhys factor (S = 97+-1). Notably, we identify the longitudinal optical (LO) phonon mode at 84 cm-1 which plays a significant role in electron-phonon interaction. Our results show these STEs not only intensify the PL spectra at lower temperatures but also induce a shift in the color emission, transforming it from a light orange-red to an intense bright strong red.