Solution-Processed Double-Silicon-Bridged Oxadiazole/Arylamine Hosts for High-Efficiency Blue Electrophosphorescence

Abstract

A series of oxadiazole/arylamine hybrids, namely pOXDDSiPA, pOXDDSiCz, mOXDDSiPA, and mOXDDSiCz, were designed and synthesized by incorporating electron-donating diphenylamine or 3,6-di-tert-butyl-9H-carbazole unit and electron-accepting oxadiazole moiety into one molecule via double-silicon-bridged linkage. This design strategy of extending molecular structure endows these compounds with good solution processability, and high thermal and morphological stability, without lowering their triplet energies. These compounds exhibit similar energy levels and higher glass transition temperatures (92–190 °C) relative to the corresponding single-silicon-bridged congeners. The reasonable combination of the tetra-meta-position linking topology and electron donor diphenylamine group imparts the compound mOXDDSiPA with both relative high triplet energy (2.72 eV) and high-lying HOMO level (5.30 eV). As a result, the best EL performance was achieved for the mOXDDSiPA-based blue phosphorescent device, with a maximum curr...