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

Raj Pandya, Arjun Ashoka, Kyriacos Georgiou, Jooyoung Sung, Rahul Jayaprakash, Scott Renken, Lizhi Gai, Zhen Shen, Akshay Rao, Andrew J. Musser

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

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.

Original languageEnglish
Article number2105569
JournalAdvanced Science
Volume9
Issue number18
DOIs
StatePublished - 23 Jun 2022

Bibliographical note

Publisher Copyright:
© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.

Keywords

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

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