Carbazole-pyridine pyrroloquinoxaline/benzothiadiazine 1,1-dioxide based bipolar hosts for efficient red PhOLEDs

Two novel bipolar hosts Cbz-Py-PQ and Cbz-Py-SA have been designed, synthesized, and eventually successfully used for fabrication of red phosphorescent organic light-emitting diodes (PhOLEDs). Considering higher hole mobility than that of electron mobility in most of the bipolar host with 1:1 donor: acceptor ratio, herein we have made it 1:2 by linking carbazole (donor core) to pyrroloquinoxaline/benzothiadiazine 1,1-dioxide (acceptor core) through pyridine (acceptor core) featuring donor-acceptor-acceptor (D-A-A) architecture. Structure-property-performance relationship have been realized through evaluation of thermal, photophysical and electrochemical properties of both the molecules. Cbz-Py-PQ hosted red PhOLED revealed maximum efficiencies of 16.4%, 9.6 cd A−1 and 9.4 lm W−1 with maximum luminance of 20753 cd m−2 at 11.0 V.