Twisted-terphenyl conjugated carbazole derivatives with aggregation-induced emission enhancement for deep-blue fluorescence in the solid state

Abstract

Scarcity of highly efficient, stable and pure deep-blue chromophores is a key impact on application of OLEDs. In this study, four bipolar molecules were designed and synthesized using carbazolyl as donor and oxadiazole/triazole as acceptors via a twisted terphenyl bridge substituted with trimethylsilyl group. These materials show high thermal/morphological stabilities and deep-blue emission benefited by the twisted structures with high fluorescent efficiency in the solid states. The dual emission properties are well tuned via different acceptors and conjugation sites with aggregation-induced emission enhancement. Electroluminescent device using p-CSiTO as a dopant was fabricated and this device emits deep-blue light at 437 nm with Commission Internationale de l’Eclairage (CIEx',y) of (0.159, 0.110) and good colour purity with full width half maximum (FWHM) of 66 nm.