Tuning the Coherent Propagation of Organic Exciton-Polaritons through Dark State Delocalization.
Published version
Peer-reviewed
Repository URI
Repository DOI
Change log
Authors
Abstract
While there have been numerous reports of long-range polariton transport at room-temperature in organic cavities, the spatiotemporal evolution of the propagation is scarcely reported, particularly in the initial coherent sub-ps regime, where photon and exciton wavefunctions are inextricably mixed. Hence the detailed process of coherent organic exciton-polariton transport and, in particular, the role of dark states has remained poorly understood. Here, femtosecond transient absorption microscopy is used to directly image coherent polariton motion in microcavities of varying quality factor. The transport is found to be well-described by a model of band-like propagation of an initially Gaussian distribution of exciton-polaritons in real space. The velocity of the polaritons reaches values of ≈ 0.65 × 106 m s-1 , substantially lower than expected from the polariton dispersion. Further, it is found that the velocity is proportional to the quality factor of the microcavity. This unexpected link between the quality-factor and polariton velocity is suggested to be a result of varying admixing between delocalized dark and polariton states.
Description
Funder: EPSRC; Id: http://dx.doi.org/10.13039/501100000266
Funder: U.S. Department of Energy; Id: http://dx.doi.org/10.13039/100000015
Funder: Office of Science; Id: http://dx.doi.org/10.13039/100006132
Funder: Basic Energy Sciences; Id: http://dx.doi.org/10.13039/100006151
Keywords
Journal Title
Conference Name
Journal ISSN
2198-3844