Versatile azaryl-ketone-based blue AIEgens for efficient organic light-emitting diodes

We report two donor-acceptor type blue luminophores based on an azaryl-ketone derivative, phenyl(3-phenylimidazo[1,2-a]pyridin-2-yl)methanone (pBZ), as respectively emitter and host materials for organic light-emitting diodes (OLEDs). The two new compounds pBZ-TPA and pBZ-DPA having varying lengths of phenylene linkers are prepared through a facile synthetic method and systematically investigated with thermal, photophysical, electroluminescent, and theoretical studies. They exhibit obvious aggregation-induced emission (AIE) characters. The electron-deficiency pBZ and the electron-rich arylamine (triphenylamine or diphenylamine) respectively serve as electron acceptor and donor, rendering bipolar electronic properties. The two AIE luminophores (AIEgens) exhibit obvious charge transfer character evidenced by positive solvatochromic effect in their photoluminescence. It is also found that the (bi)phenylene π-linker attached in donor would tune the molecular conjugation and degree of charge transfer. The versatility of pBZ-TPA and pBZ-DPA is demonstrated in blue OLEDs as emitters and in red phosphorescent devices as hosts with decent performance and mild efficiency roll-offs.