Polariton transport in 2D semiconductors: Phonon-mediated transitions between ballistic, superdiffusive, and exciton-limited regimes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41237241.
- Also identified by DOI 10.1126/sciadv.aea3495 and PMC identifier 13142775.
- 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
Exciton transport in 2D semiconductors holds promise for room temperature, ultracompact optoelectronic devices, but it is limited by short propagation distances. Hybridization of excitons with cavity photons to form exciton-polaritons can enhance the propagation by orders of magnitude, enabling a coherent, ballistic transport. However, a microscopic understanding of the role of phonons is still lacking, particularly regarding their influence on the crossover from the ballistic to the diffusive polariton transport regime. Here, we investigate the spatiotemporal polariton dynamics in MoSe<sub>2</sub> monolayers at moderate to high temperatures, explicitly including the phonon-mediated coupling to the intervalley exciton reservoir. We identify three distinct transport regimes: (i) an initial subpicosecond ballistic-like regime characterized by a phonon-induced velocity renormalization, (ii) a transient, few-picosecond superdiffusive regime characterized by strongly enhanced diffusion, and (iii) a slower, exciton-limited diffusion following thermalization. The gained microscopic insights will trigger and guide future experimental studies on the phonon-mediated polariton transport in atomically thin semiconductors.