DFT Study on Two Kinds of Electron-transport Materials: 1,3,4-oxadiazole Derivatives and 1,2,4-triazole Derivatives

The simplest organic light-emitting-diode (OLED) device is a two layer device of: ITO/HTL/ETL/Mg: Ag, in which HTL or ETL can act as light emitter. The mobilities of charge are important in optimizing the performance of OLED devices, as high mobilities reduce the resistance of the device leading to greater power efficiency. The electron-transport in the organic solid can be viewed as an electron hopping process. By means of DFT (B3LYP) methods, the structures of two kinds of electron-transport materials in neutral, cationic and anionic states were optimized. The results suggest that the process of electronic transmission of 2,5-diphenyl-1,3,4-oxadiazole is mainly the N→O transferences, the process of electronic transmission of 3,4,5-triphenyl-1,2,4-triazole is mainly the N(double linkage)→N(single linkage) transferences and the transition from the triazole ring to the benzene ring connected with the N atom. The third position of the benzene ring was substituted by the electron acceptor groups, the electronic transmission performance was enhanced, while it was substituted by the electron donor groups, the electronic transmission performance was reduced.