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Tuning the Coherent Propagation of Organic Exciton-Polaritons through Dark State Delocalization.

Published version
Peer-reviewed

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Authors

Pandya, Raj 
Ashoka, Arjun 
Georgiou, Kyriacos 
Sung, Jooyoung 
Jayaprakash, Rahul 

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

Q-factor, TA microscopy, coherent transport, dark states, energy transport, exciton-polaritons

Journal Title

Adv Sci (Weinh)

Conference Name

Journal ISSN

2198-3844
2198-3844

Volume Title

Publisher

Wiley
Sponsorship
Early Career Research Program (DE‐SC0021941))
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