Sky- blue fluorescent small- molecules with high quantum efficiency: synthesis, structures, AIE properties, and applications in solution- processed non- doped OLEDs

Solution processed blue organic luminescent materials are in great demand toward new generation displays fabrication by low-cost printing technique, but most are far from satisfactory. In this context, two novel isomeric fluorophores, 9CzTPE and 3CzTPE, that contain tetraphenylethylene, carbazole, and fluorene species were synthesized by variation of the linkage modes. The thermal, photophysical, electrochemical, and aggregation-induced emission (AIE) properties of the resulting fluorophores were systematically investigated. Both 9CzTPE and 3CzTPE exhibit evident AIE properties and achieve sky-blue emission with a high solid-state fluorescence quantum yield of more than 60%. The solution-processed non-doped organic light-emitting diode based on 3CzTPE exhibits excellent performance, with high luminous efficiency of 4.35 cd A(-1) and a maximum external quantum efficiency of 2.81% with the emission peak at 479 nm. These results open a novel approach for the facile construction of highly efficient blue light-emitting AIE fluorophores for solution-processed dopant-free organic light-emitting diodes.