Aryl-substituted acridanes as hosts for TADF-based OLEDs

Four aryl-substituted acridan derivatives were designed, synthesized and characterized as electroactive materials for organic light emitting diodes based on emitters exhibiting thermally activated delayed fluorescence. These compounds possessed relatively high thermal stability with glass-transition temperatures being in the range of 79-97 °C. The compounds showed oxidation bands arising from acridanyl groups in the range of 0.31-038 V. Ionization potentials of the solid films ranged from 5.39 to 5.62 eV. The developed materials were characterized by triplet energies higher than 2.5 eV. The layer of 10-ethyl-9,9-dimethyl-2,7-di(naphthalen- 1-yl)-9,10-dihydroacridine demonstrated hole mobilities reaching10^-3 cm2/V·s at electric fields higher then ca. 2.5 × 10⁵ V/cm. The selected compounds were used as hosts in electroluminescent devices which demonstrated maximum external quantum efficiencies up to 3.2%.