Versatile Donor-π-Acceptor-Type Aggregation-Enhanced Emission Active Fluorophores as Both Highly Efficient Nondoped Emitter and Excellent Host

By employing triphenylamine (TPA) and/or carbazole as donor and cyano group as acceptor, three donor-π-acceptor (D-π-A)-type fluorophores, 4,6-di(4-(diphenylamino)phenyl)isophthalonitrile (DTPAIPN), 4-(4-(diphenylamino)phenyl)-6-(3,5-(9,9'-dicarbazolyl)phenyl)isophthalonitrile (TPAmCPIPN), and 4,6-di(3,5-(9,9'-dicarbazolyl)phenyl)isophthalonitrile (DmCPIPN), were designed, synthesized, and characterized for their thermal, photophysical, electrochemical, and electroluminescent properties. All three compounds exhibited excellent thermal and morphological stabilities with thermal decomposition (T_d) and glass transition temperature (T_g) values ranging from 396 to 516 °C and from 114 to 211 °C, respectively. The investigation into the photophysical properties revealed the aggregation-enhanced emission (AEE) feature of these chromophores. The performances of the nondoped devices were significantly improved as compared to those of the doped devices, further confirming the AEE nature. In particular, DmCPIPN-based nondoped device rendered the maximum current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE) values of 26.6 cd A^-1, 22.4 lm W^-1, and 8.3%, respectively, in comparison with 9.1 cd A^-1, 4.9 lm W^-1, and 4.2% for the doped device. The versatility of these new luminogens was demonstrated through the utilization of them as host for highly efficient red phosphorescent organic light-emitting diodes (PHOLEDs). The EQE of the DmCPIPN-hosted device reached as high as 19.3% with a reduced efficiency roll-off of 10.3% at 1000 cd m^-2. These results demonstrate that the new luminogens of this work can be used as both nondoped emitter and host for high-performance OLEDs, which facilitates the development of multifunctional materials for OLEDs applications.