Electron rich N-heterotriangulenes as host materials for OLEDs

Abstract

Triphenylamine-based materials have been extensively studied as hole-transporting materials for organic semiconductor devices due to their high hole mobility and thermal stability. For example, they may be used as either hole-transporting layers in solar cells or p-type host materials in the emissive layer of OLEDs. Here, we present the development of a series of fused triarylamine derivatives in the form of N-heterotriangulene-based systems featuring electron-rich pendent groups and have investigated their structural properties using X-ray crystallography, and their optical and redox properties. Space-charge-limited current measurements were carried out to assess their potential to be used as p-type materials and the materials were applied as hosts in OLEDs with a solution-processed 4CzIPN-doped emissive layer. The best-performing devices exhibited a maximum external quantum efficiency of 6.9%. We have shown that the host can disperse the emitter molecules effectively and avoid dimer formation thereby enhancing OLED performance.