Triphenylamine-Imidazole based Luminophores for Deep-blue Organic Light Emitting Diodes: Experimental and Theoretical Investigations
In this paper, three deep blue donor-acceptor (D-A) luminophores, triphenylamine bearing hole-transporting system and imidazole as an electron-transporting system were synthesized by a condensation reaction and characterized by spectroscopic methods. The detailed thermal, optical, electrochemical and electroluminescence properties were systematically investigated. The synthesized luminophores have good thermal stability and good PLQY as well. The UV-vis spectra of the luminophores show multiple absorption bands (UV to near UV region, due to π–π* transitions of the aromatic segments). All the luminophores showed blue emission in the DCM solution. solution-processable OLEDs were fabricated by using these luminophores as an emitting dopant in 4,4′-bis(9H-carbazol-9-yl)biphenyl host and found to exhibit bright deep blue EL emission. Among these luminophores, one donor–two acceptors (DBIPTPA) luminophore displayed promising deep blue emission characteristics with more than 100% color saturation when compared with the NTSC standard. The fabricated device with DBIPTPA is shown high luminance of 495 cd m-2 and 2.5% external quantum efficiency with CIE coordinate of (0.16, 0.06) at the brightness 100 cd m-2.