In the characterisation of thermally activated delayed fluorescence (TADF) emitters for OLEDs, focus is usually laid on the lowest excited states S1 and T1. Upper excited states Sn>1 and Tn>1 can influence the kinetics of TADF by quantum mechanical admixing. The energies of these upper states ought to be accessible by time resolved NIR spectroscopy. In a study led by the ModISC postdoc Bárbara Elza Nogueira de Faria, it was shown that this is indeed the case. The respective TADF emitter consisting of a triarylamine donor and an 1,4-dicyanobenzene acceptor moiety was synthesized by Laura N. Kloeters in Thomas J.J. Müller’s group. In Peter Gilch’s lab, time resolved spectroscopy was conducted by Wiebke Haselbach and Bárbara Elza Nogueira de Faria. The NIR transitions detected thereby are in superb accordance with quantum chemical computations by Jeremy M. Kaminski and Oliver Weingart working in Christel M. Marian’s group. We are confident that such NIR characterizations will aid in optimizing TADF emitters in the future.
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Investigating a TADF Emitter by Time Resolved Near Infrared Spectroscopy
Wiebke Haselbach, Jeremy M. Kaminski, Laura N. Kloeters, Thomas J. J. Müller, Oliver Weingart, Christel M.Marian, Peter Gilch, Barbara E. Nogueira de Faria
Chemistry - A European Journal