Exciplex Organic Light-Emitting Diodes with Nearly 20% External Quantum Efficiency: Effect of Intermolecular Steric Hindrance between the Donor and Acceptor Pair.

Exciplex emitters have emerged as an important class of thermally activated delayed fluorescence (TADF) materials for highly efficient OLEDs. A TADF exciplex emitter requires an intermolecular donor/acceptor pair. We have synthesized a bipolar donor-type material, DPSTPA, which was used to pair with known acceptor materials (2CzPN, 4CzIPN, or CzDBA).