Synthesis and luminescence properties of V-shaped bis-coumarins with the benzophenone-imbedded triptycene and carbazole

Two new V-shaped bis-coumarins (VBC) with the benzophenone-imbedded triptycene and carbazole, VBC-COTTC and VBC-CO-Cz, were synthesized and characterized by NMR (1H and 13C), high resolution mass spectrometry and elemental analysis, and their thermal stabilities and photophysical and electrochemical properties were systematically studied. They exhibited strong green emission with high fluorescence quantum yield of 90.4 % and 93.65 % in dichloromethane solution, respectively. The combination of theoretical research and experimental data revealed the structure-property relationship of the functional groups grafted onto the V-shaped biscoumarins. Moreover, the doped devices treated with the blend of CBP:VBC derivatives as the emitting layers showed green emission, in which the VBC-CO-Cz doped devices exhibited an maximum external quantum efficiency (EQEmax) of 2.66 %, while the VBC-CO-TTC doped devices showed an EQEmax of 1.79 %, at the doping concentration of 5 wt%.