Enhanced Delayed Fluorescence in Non-Local Metasurfaces: The Role of Electronic Strong Coupling

TL;DR

This paper demonstrates that non-local metasurfaces with aluminum nanoparticle arrays can significantly enhance delayed fluorescence in organic molecules through increased absorption, with strong coupling playing a minimal role, supported by simulations.

Contribution

It introduces a novel design of open cavities with non-local metasurfaces that enhance delayed fluorescence via increased absorption, clarifying the role of strong coupling.

Findings

Delayed fluorescence is enhanced by a factor of 2.0-2.6.

Enhancement is mainly due to increased absorption, not strong coupling effects.

Finite-difference-time-domain simulations support the experimental results.

Abstract

Strong light-matter coupling has garnered significant attention for its potential to optimize optoelectronic responses. In this study, we designed open cavities featuring non-local metasurfaces composed of aluminum nanoparticle arrays. The surface lattice resonances in these metasurfaces exhibit electronic strong coupling with the boron difluoride curcuminoid derivative, known for its highly efficient thermally activated delayed f luorescence in the near-infrared. Our results show that delayed fluorescence induced by triplet-triplet annihilation can be enhanced by a factor of 2.0-2.6 in metasurfaces that are either tuned or detuned to the molecular electronic transition. We demonstrate that delayed fluorescence enhancements in these systems primarily stem from increased absorption in the organic layer caused by the nanoparticle array, while strong coupling has negligible effects on reverse intersystem crossing rates, aligning with previous studies. We support these findings with finite-difference-time-domain simulations. This study elucidates how light-matter interactions affect delayed fluorescence, highlighting the potential applications in optoelectronic devices.