Unexpected Quasi?Axial Conformer in Thermally Activated Delayed Fluorescence DMAC?TRZ, Pushing Green OLEDs to Blue

Hidden photophysics is elucidated in the very well-known thermally activated delayed fluorescence (TADF) emitter, DMAC-TRZ. A molecule that, based on its structure, considered not to have more than one structural conformation. However, experimental and computational studies, two conformers, a quasi-axial (QA) quasi-equatorial (QE) are found, effect of their co-existence both optical electrical excitation isexplored. The relative small population QA conformer has disproportionate because strong local excited state character. energy transfer efficiency from QE high, even at low concentrations, dependent host environment. current accepted triplet DMAC-TRZ shown originate conformer, completely changing understanding contribution devices helps explain good performance material non-doped organic light-emitting diodes (OLEDs). Moreover, hyperfluorescence (HF) devices, using v-DABNA emitter show direct v-DABNA, explaining relatively improved Förster resonance compared similar HF systems. Highly efficient OLEDs where green light (TADF-only devices) converted blue (HF with maximum external quantum remaining close 30% demonstrated.