Macrocyclic and acyclic bis(2,5-diphenyl-1,3,4-oxadiazole)s with electron-transporting and hole-blocking ability in organic electroluminescent devices

Two types of bis(2,5-diphenyl-1,3,4-oxadiazole)s, macrocyclic and acyclic, were prepared and evaluated as electron-transporting and hole-blocking materials in phosphorescent EL devices. Maximum efficiencies of eta(ext)=10.4% at J=0.11 mA.cm(-1) for the macrocycle and eta(ext)=14.1% at J=3.01 mA.cm(-1) for the acycle were observed. X-ray crystallographic analysis and DSC measurements revealed a strong intermolecular interaction between the macrocylces and weaker intermolecular interactions between the acycles. The EL characteristics depend on the intermolecular interactions.