Design and Synthesis of Novel Phenothiazine-Benzothiadiazine-1,1-dioxide Hybrid Organic Material for OLED Applications

In this study, yellow thermally activated delayed fluorescence (TADF) emitter PTZ-SA has been designed and synthesized by incorporating phenothiazine as donor and benzothiadiazine-1,1-dioxide as an acceptor. The molecule is also screened for aggregation induced emission in THF/Water system. PTZ-SA shows exceptionally high glass transition temperature (T-g) of 188 degrees C which clearly highlights good thermal stability of the material. The energy gap (Delta E-ST) between singlet (S1) and triplet (T1) excitons is sufficiently small (0.08 eV) for the reverse intersystem crossing. Yellow electroluminescence peak is observed at 568 nm with Commission Internationale de L ' Eclairage coordinates of (0.44, 0.50). The external quantum efficiency of 4.2 % from PTZ-SA is achieved in yellow emitting OLED with turn on voltage of 5.1 V. Moreover, sufficiently high triplet energy of 2.5 eV and good film forming ability of PTZ-SA, encouraged us to study its electro-phosphorescent properties. Nevertheless, the red phosphorescent OLED device incorporating PTZ-SA dopped with a red emitter Ir(piq)(2)acac exhibited maximum external quantum efficiency, power efficiency and luminescence efficiency of 8.1 %, 7.2 lm W-1 and 5.1 cd A(-1), respectively.