Tailoring dynamics of thermally activated delayed fluorescence molecules embedded in cavity by forming coupling-induced hybrid states

Light–matter coupling-induced hybrid states provide the potential to tune the emission dynamics of molecular chromophores having multilevel systems. We demonstrate the alteration of delayed fluorescence dynamics by hybrid states formation through the interaction of light with a thermally activated delayed fluorescence molecule embedded in a conventional Fabry–Pérot cavity. The proximity of cavity resonance with the excited state absorption is modified by manipulating the incident angles (with sample) instead of varying the active layer thickness. The coupling-induced hybrid states are observed by angle-dependent emission spectroscopy and lifetime measurements. The variation in average emission lifetime with respect to incident angle is over 10 μs and is accompanied by significant changes in the full width at half maxima (factor of three). The control of emission via a barrier-free route or reverse intersystem crossing transition is demonstrated from these measurements. These findings suggest the possibility of tailoring intermediate states for lasing, where exciton density inversion can enhance spontaneous emission.