Synthesis and electro-optical properties of carbazole derivatives for organic device applications

Two materials, DNCz and TCzPB, which contain carbazole moieties and exhibit high band gap energies, were synthesized via CN coupling and Suzuki coupling reactions, respectively. The ionization potential and electron affinity of the synthesized TCzPB were measured at 5.89 and 2.39 eV, respectively, implying that it is suitable for a host material. A doped multilayer device, ITO/DNTPD/NPD/TCzPB + Ir(ppy)3/BCP/Alq3/LiF/Al, exhibited a bright green emission with a maximum luminance of 27,200 cd/m2 (17.6 cd/A at 18.0 V) when the synthesized TCzPB was used as the host material for a phosphorescent green dopant. The compound DNCz exhibited similar electronic energy levels to those of NPD, and was applied as a hole-transporting material. Bright green light originated from the Alq3 layer was observed in the double layer device, ITO/DNCz/Alq3/LiF/Al. The high hole-transporting property of DNCz was also demonstrated.