Systemic studies of tetraphenylethene-triphenylamine oligomers and a polymer: achieving both efficient solid-state emissions and hole-transporting capability.

By employing a new synthetic strategy, a series of oligomers and a polymer composed of different number of tetraphenylethene and triphenylamine units was designed and synthesised. The optical physics properties and electroluminescence behaviours were studied comparatively. All the molecules demonstrate an aggregation-induced emission (AIE) phenomenon and bear very high quantum yields in the solid state. The emission wavelengths and quantum efficiencies alternate with the change of the molecular configurations and achieve their maximum at the largest oligomer. The thermal stabilities also become higher along with the increase in the molecular weight. The molecules have suitable HOMO levels that match the work function of the indium tin oxide (ITO) anode. They can act as both light-emitting and hole-transporting materials in OLEDs. Thus the present strategy combines the intrinsic emissive nature of AIE materials and the good hole-transport capability of aromatic amines, thereby achieving a win-win for both optical and electrical properties.