Triazatruxene: A Rigid Central Donor Unit for a D–A3 Thermally Activated Delayed Fluorescence Material Exhibiting Sub‐Microsecond Reverse Intersystem Crossing and Unity Quantum Yield via Multiple Singlet–Triplet State Pairs

• DOI: 10.1002/advs.201700989
• Publication Date: 2018-04-16T15:22:18Z
• Authors: Paloma L. dos Santos; Jonathan S. Ward; Daniel G. Congrave; Andrei S. Batsanov; Julien Eng; Jessica E. Stacey; Thomas J. Penfold; Andrew P. Monkman; Martin R. Bryce
• Keywords: Intersystem crossing; Quantum yield; Microsecond; Quantum Efficiency; Acceptor

Abstract By inverting the common structural motif of thermally activated delayed fluorescence materials to a rigid donor core and multiple peripheral acceptors, reverse intersystem crossing (rISC) rates are demonstrated in an organic material that enables utilization triplet excited states at faster than Ir‐based phosphorescent materials. A combination inverted structure donor–acceptor interactions yields up 30 vibronically coupled singlet within 0.2 eV involved rISC. This gives significant enhancement rISC rate, leading decay times as low 103.9 ns. new also has emission quantum yield ≈1 very small singlet–triplet gap. work shows it is possible achieve both high photoluminescence fast same molecule. Green light‐emitting diode devices with external efficiency >30% 76 cd m −2 .