Synthesis and characterization of yellow-emitting electrophosphorescent polymers based on a fluorinated poly(arylene ether phosphine oxide) scaffold

Abstract

A series of novel yellow-emitting electrophosphorescent polymers (PhPs) have been designed and synthesized by grafting a 2-(fluoren-2-yl)-1H-benzoimidazole ligand based iridium complex, (fbi)₂Ir(acac), with a fluorinated poly(arylene ether phosphine oxide) backbone (FPCzPO). Due to the efficient intermolecular Förster energy transfer from FPCzPO to (fbi)₂Ir(acac) and charge trapping on (fbi)₂Ir(acac), the electroluminescence from FPCzPO is almost completely quenched, even if the Ir complex content incorporated into the polymer is as low as 2 mol%. It is found that the polymer exhibits the best device performance when the Ir loading is optimized to 3 mol%. A peak luminous efficiency of 10.4 cd A⁻¹ with Commission Internationale de L'Eclairage coordinates of (0.53, 0.46) is achieved, which is superior to that of the previously reported yellow PhPs with polyfluorene as the main chain. The result indicates that the fluorinated poly(arylene ether phosphine oxide) is a promising scaffold for the construction of efficient yellow PhPs.