Efficient binary white light-emitting polymers grafted with iridium complexes as side groups

Abstract

Efficient binary white-light-emitting electrophosphorescent copolymers were designed and synthesized via Suzuki polymerization. These copolymers were constructed by grafting a small amount of fluorinated iridium complexes as the side chain of the poly(fluorene-co-2,3-bisphenyl-6-fluoroquinoxaline) backbone. Efficient white-light emission was obtained simultaneously from the fluorescent blue light-emitting backbone and the tethered phosphorescent yellow light-emitting iridium species. A peak luminous efficiency of 7.20 cd A⁻¹ with the Commission Internationale de l'Eclairage coordinates of (0.32, 0.38) were obtained based on copolymer PFQ-IrFppy. The white-light emission of devices from the copolymer is stable over the whole white-light region at various applied voltages, and the luminous efficiencies decline slightly with increasing current density. These observations highlighted that the strategy of utilizing both the blue fluorescence from the backbone and yellow phosphorescence from the side chains can be an encouraging approach to realize efficient binary white light-emission.