Exciton-Resolved Phonon Coupling and Energy Dissipation Pathways in CsPbBr<sub>3</sub>.

H L, Pradeepa; Chatterjee, Sagnik; Patra, Sayantan; Bisoi, Swapneswar; Mushtaq, Saqlain; Singh, Akshay; Arora, Ashish; Rahman, Atikur · ACS Nano · 2026

basic_science · Level V

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Abstract

Exciton-phonon interactions govern the optical response of semiconductors, yet disentangling multiple coupling channels in lead halide perovskites remains challenging. We investigate CsPbBr<sub>3</sub> microcrystals using photoluminescence, Raman, and reflectance spectroscopy at low temperature, revealing the simultaneous presence of high-energy and Rashba excitons, each accompanied by distinct phonon replica series. High-energy exciton replicas are uniquely spaced by approximately 9 meV, whereas Rashba exciton replicas exhibit a characteristic approximately 6 meV spacing, indicating the specificity of the exciton-phonon coupling. k-means clustering applied to a large low-temperature photoluminescence data set reveals these replica features are prevalent. With increasing temperature, replica features broaden and merge, evolving into a dominant longitudinal optical phonon coupling regime at room temperature. This work establishes direct spectroscopic evidence for concurrent, exciton-specific phonon coupling within a single material, offering pathways to engineer light-matter interactions for optoelectronic and phonon-photon-based quantum device applications.