Efficient anisotropic polariton lasing using molecular conformation and orientation in organic microcavities
Author(s)
Le Roux, Florian
Mischok, Andreas
Bradley, Donal DC
Gather, Malte C
Type
Journal Article
Abstract
Organic exciton-photon polariton lasers are promising candidates for the efficient generation of coherent light at room temperature. While their thresholds are now comparable with those of conventional organic photon lasers, tuning of molecular conformation and orientation as a means to control fundamental properties of their emission and thus further enhance performance remains largely unexplored. Here, a two-fold reduction in the threshold of a microcavity polariton laser based on an active layer of poly(9,9-dioctylfluorene) (PFO) is achieved when 15% β-phase conformation is introduced. In addtion, taking advantage of the liquid crystalline properties of PFO, a thin photoalignment layer is used to induce nematic alignment of the polymer chains. The resulting transition dipole moment orientation increases the Rabi energy, bringing the system into the ultra-strong coupling regime and facilitating anisotropic polariton lasing with an eight-fold reduction in absorbed threshold, down to 1.14 pJ (0.36 µJ cm−2) for the direction parallel to the orientation, with no emission along the orthogonal direction. This represents the first demonstration of anisotropic polariton lasing in conjugated polymer microcavities and a lower threshold than current organic vertical cavity surface-emitting photon and polariton lasers. Dipole orientation offers new opportunities for switchable, more efficient polaritonic devices, and observation of fundamental effects at low polariton numbers.
Date Issued
2022-11-10
Date Acceptance
2022-09-01
Citation
Advanced Functional Materials, 2022, 32 (46)
ISSN
1616-301X
Publisher
Wiley
Journal / Book Title
Advanced Functional Materials
Volume
32
Issue
46
Copyright Statement
© 2022 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Publication Status
Published
Article Number
2209241
Date Publish Online
2022-09-18