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Published September 8, 2022 | public
Journal Article

Dual Fluorescence of Octatetraene Hints at a Novel Type of Singlet-to-Singlet Thermally Activated Delayed Fluorescence Process

Abstract

A novel type of singlet-to-singlet thermally activated delayed fluorescence (STS-TADF) from the optically bright 1⁺Bᵤ⁺ and dark 2¹A_(g)⁻ states of octatetraene is proposed based on state-of-the-art ab initio simulations. The new phenomenon bears similarity with TADF, the key difference being that in the normal TADF the emissive state is repopulated from a nearby triplet, whereas in STS-TADF it occurs from a nearby dark singlet state (2¹A_(g)⁻). The nonadiabatic populations of the bright and dark singlet excited states are dynamically redistributed through a conical intersection mediated by an ultrafast skeleton C–C stretching vibration, establishing a steady state for a sufficiently long time to undergo radiative decay. The steady state manifests itself in the experimentally observed dual fluorescence. It is expected that the STS-TADF can be observed in other π-conjugated chromophores as well.

Additional Information

C.H.C. thanks the Samsung Science and Technology Foundations (SSTF-BA1701-12) and the National Research Foundation of Korea (2020R1A2C2008246 and 2020R1A5A1019141). This work was also supported by the Korea Polar Research Institute (KOPRI, PE22120) funded by the Ministry of Oceans and Fisheries. P.P. thanks the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (DE-FG02-01ER15228).

Additional details

Created:
August 22, 2023
Modified:
October 24, 2023