Multiple-resonant nitrogen embedded nanographenes with high photoluminescence efficiency and high colour purity

A feasible approach by decorating pi-extensions with nitrogen is proposed to realize narrow-band emitting NGs with multiple resonance (MR) effect. Pure blue and green NGs were obtained under mild reaction conditions in high yields. Both NGs featured high photoluminescence quantum yields (>90%) with emission peaks at 454 and 516 nm, small full widths at half maxima (FWHMs) of 18 and 23 nm, and high colour saturation with y-coordinates of 0.083 and 0.73, respectively. OLEDs using these NGs as emitters exhibited ideal blue (459 nm) and green (532 nm) emissions with high colour purity and small FWHMs of 25 and 21 nm, respectively.