Naphthyridine-based iridium(iii) complexes for green to red OLEDs with EQEs over 30% and low efficiency roll-off

Four new naphthyridine-based iridium(iii) complexes, namely (dfpmp)(2)Ir(mmND), (mtfmpp)(2)Ir(mmND), (tfmptp)(2)Ir(mmND), and (mtfmptp)(2)Ir(mmND), were designed and synthesized. The complexes show tunable emission peak wavelengths from 521 nm to 600 nm with relatively high photoluminescence quantum yields (PLQYs) of 80-85% in CH2Cl2. Employing these emitters, all the organic light-emitting diodes (OLEDs) exhibit prominent performances with the maximum external quantum efficiency (EQE(max)) exceeding 30%, and simultaneously the efficiency roll-off is extremely low. Of note, the double emissive layer OLED using (mtfmpp)(2)Ir(mmND) as the dopant achieves the optimal electroluminescence (EL) performances with an EQE(max) of 32.3% and an ultrahigh brightness of 242 548 cd m(-2).