Organic Light-Emitting Materials and Devices, 2nd Edition

3.5.1.2.3.3 Heterocyclic Compounds Pyrazole-containing compounds are useful blue dyes. Tao’s group studied a series of pyrazolo [3,4-b]quinoline derivatives as blue emitters (Scheme 3.53) [379]. An EQE about 3.5% using one of the dopants 4-(p-methoxyphenyl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]quinoline (MeOPAQ-H) (311) in an OLED with a configuration of ITO/NPD/CBP/TPBI:MeOPAQ-H/TPBI/Mg:Ag was achieved. A brightness of 13,000 cd/m² with a blue emission CIE (0.19, 0.16) was demonstrated. Other pyrazole derivatives such as Pyzo-1 (312) and Pyzo-2 (313) also emitted blue light; however, the EL performance is rather poor [380]. Phenanthrolines, e.g., BCP, widely used as hole-blocking materials, were used as blue-emitting materials in the late 1990s ...