Synthesis and electro-optical properties of carbazole derivatives with high band gap energy

Two materials containing carbazole moieties and exhibiting a high band gap energy, 3,8-di(9H-carbazol-9-yl)-6-phenylphenanthridine (DCzP) and 3,6-di(naphthalene-2-yl)-9-phenyl-9H-carbazole (DNaC), were synthesized via CN coupling and Suzuki coupling reactions, respectively. The compound DCzP exhibited blue emission with the CIE coordinates of x = 0.165 and y = 0.136 from the OLED device, ITO(indium–tin oxide)/NPB(N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)benzidine)/DCzP/LiF/Al. The doped device, ITO/2-TNATA(4,4′,4″-Tris(2-naphtylphenyl-phenylamino) triphenyl amine)/NPB/DCzP + Ir(ppy)3/BCP(2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline)/Alq3(tris(8-hydroxyquinoline)aluminum/LiF/Al, showed bright yellowish-green emission with a maximum luminance of 23,000 cd/m2 when the synthesized DCzP was applied as a host material for the phosphorescent green dopant. From the double layer device, ITO/DNaC/Alq3/LiF/Al, in which DNaC was used as the hole transporting material, the yellowish-green color arising from the Alq3 was also observed.