Low inhomogeneous broadening of excitonic resonance in MAPbBr3 single crystals

TL;DR

This study demonstrates that MAPbBr3 single crystals exhibit exceptionally low inhomogeneous broadening of excitonic resonance, comparable to high-quality epitaxial structures, with resolved phonon replicas confirming strong exciton-phonon coupling.

Contribution

It provides the first observation of phonon replicas in MAPbBr3 photoluminescence spectra, indicating high crystal quality and detailed exciton-phonon interactions.

Findings

Inhomogeneous broadening of ~0.5 meV observed

Excitonic resonance confirmed by superlinear pump dependence

Phonon replicas resolved in PL spectra

Abstract

We present optical study of MAPbBr3 single crystals grown from solution by inverse temperature crystallization method. Photoluminescence temperature dependence of narrow and isolated exciton resonance showed encouragingly low inhomogeneous broadening {\Gamma} ~ 0.5 meV, which is comparable to those of MBE-grown III-V heterostructures, indicating high quality of the solution-grown perovskite. Excitonic origin of the resonance was proved by its superlinear pump intensity dependence in contrast to the linear behavior of the defect-assisted recombination bands. In addition, for the first time phonon replicas were resolved in MAPbBr3 photoluminescence spectra and attributed to the known lattice vibrational modes by comparison with Raman scattering spectra.