Vibrationally Assisted Intersystem Crossing in Benchmark Thermally Activated Delayed Fluorescence Molecules.
The journal of physical chemistry letters
American Chemical Society (ACS)
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Evans, E., Olivier, Y., Puttisong, Y., Myers, W. K., Hele, T., Menke, S., Thomas, T., et al. (2018). Vibrationally Assisted Intersystem Crossing in Benchmark Thermally Activated Delayed Fluorescence Molecules.. The journal of physical chemistry letters, 9 (14), 4053-4058. https://doi.org/10.1021/acs.jpclett.8b01556
Electrically injected charge carriers in organic light-emitting devices (OLEDs) undergo recombination events to form singlet and triplet states in a 1:3 ratio, representing a fundamental hurdle for achieving high quantum efficiency. Dopants based on thermally activated delayed fluorescence (TADF) have emerged as promising candidates for addressing the spin statistics issue in OLEDs. In these materials, reverse singlet-triplet intersystem crossing (rISC) becomes efficient, thereby activating luminescence pathways for weakly emissive triplet states. However, despite a growing consensus that torsional vibrations facilitate spin-orbit-coupling (SOC)-driven ISC in these molecules, there is a shortage of experimental evidence. We use transient electron spin resonance and theory to show unambiguously that SOC interactions drive spin conversion and that ISC is a dynamic process gated by conformational fluctuations for benchmark carbazolyl-dicyanobenzene TADF emitters.
External DOI: https://doi.org/10.1021/acs.jpclett.8b01556
This record's URL: https://www.repository.cam.ac.uk/handle/1810/282929
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/