Triphenylamine/oxadiazole hybrids differing by the substitution pattern: Influence on the electroluminescence properties of yellow and green emitting diodes

Abstract In this study, three donor-acceptor-donor triphenylamine/oxadiazole hybrids differing by the substitution pattern were synthesized and characterized by means of experimental and density functional theory (DFT) methods. The new compounds were used as hosts for the design of yellow- and green organic light emitting diodes (OLEDs), exhibiting very different EL characteristics. The position of the triphenylamine substituents relative to the central phenyl-oxadiazole-phenyl core was found to greatly influence the EL performances. The results indicate that the increased internal torsion and the disrupture of the interring π-conjugation of the hosts impacts importantly the triplet energies andthe EL performance of OLEDs. OLEDs fabricated with the best host afforded an external quantum efficiency (EQE) of 17.1%, a current and power efficiency of 59.3 cd/A and 29.5 lm/W while doping the emissive layer at 10 wt% with the triplet emitter Ir(ppy) 3 .