Synergistic insights into pyrazinophenazine based hybrid materials for advancing optoelectronics

Abstract

The crucial point of present organic light emitting diode (OLED) research is the improvement of device stability and electroluminescent efficiency. Recently, cheaply available organic compound based thermally activated delayed fluorescent (TADF) emitters are promising to resolve current issues of OLEDs. In this context, we have designed and successfully synthesized a two novel hybrid molecules 3-(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)-12,13- diphenyldibenzo[a,c]pyrazino[2,3-i]phenazine (Ac-DibzPyrQx) and 3-(4-(3,6-di‑tert‑butyl‑9H-carbazol-9-yl)phenyl)-12,13 diphenyldibenzo[a,c]pyrazino [2,3-i]phenazine (tCz-DibzPyrQx), comprising electron-donating (9,9-dimethyl-9,10-dihydroacridine, 3,6-di‑tert‑butyl‑9H-carbazole) and electron accepting Pyrazinophenazine groups. The incorporation of highly planar and rigid pyrazinophenazine electron-accepting moieties holds significant importance due to their unique properties. Their planar structure facilitates strong π-π stacking interactions and efficient charge transfer within the molecular framework, leading to improved exciton formation and enhanced intersystem crossing (ISC) rates, which are critical for TADF processes. The two different electron-donating groups with pyrazinophenazine were synthesized with the view to tune the photophysical and electrochemical properties of the hybrids. These compounds showed high thermal and morphological stability, as well as appropriate frontier molecular orbital (FMO) energy levels. These synthesized molecules show decomposition temperatures (262 °C and 282 °C) and exhibited good glass transition temperatures (328 °C and 300 °C), indicating their significant stability and potential utility as TADF emitters.