Quantum beats of exciton-polarons in CsPbI<sub>3</sub> perovskite nanocrystals.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42192106.
- Also identified by DOI 10.1038/s41467-026-73506-1 and PMC identifier 13212901.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The optical response of semiconductors is governed by coupled electronic and vibrational excitations. In lead-halide perovskite nanocrystals, strong exciton-phonon interaction forms a ladder of exciton-polaron states accessible by femtosecond laser pulses. We demonstrate a fully coherent regime of exciton-polaron dynamics with long optical coherence times (T<sub>2</sub> ≈ 300 ps) in CsPbI<sub>3</sub> nanocrystals embedded in glass. Using transient two-pulse photon echo at a temperature of 2 K, we observe quantum beats between exciton-polaron states, with decay determined by optical phonon lifetimes of 5-15 ps. Within a four-level model, we directly quantify the exciton-phonon coupling strength through Huang-Rhys factors of 0.05 - 0.12 and 0.02 - 0.04 for low-energy optical phonons with energies of 3.2 and 5.1 meV, respectively. The pronounced size dependence of both coupling strengths and phonon lifetimes offers a route to tune the optical transitions between exciton-polaron states and tailor the coherent optical dynamics in perovskite semiconductors for solid-state quantum technologies.