Synthesis and characterization of hyperbranched polyfluorenes containing triarylpyrazoline cores towards efficient blue light‐emitting diodes

Abstract

AbstractNew series of hyperbranched polyfluorenes containing triarylpyrazoline cores, PFZ10, PFZ20, PFNZ10, and PFNZ20, have been synthesized according to the “A2 + A′2 + B3” Suzuki coupling method. The structures and property of the monomers and conjugated polymers were characterized by elemental analysis, gel permeation chromatography, cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, and UV–visible absorption, 1H NMR, 13C NMR, and photoluminescence spectroscopies. All these polymers exhibited good solubility in common organic solvents and good thermal stability. The long‐wavelength emission of polyfluorenes had been effectively reduced in these hyperbranched polymers. Standard polymer light emitting devices (PLEDs) from PFZ10, PFZ20, PFNZ10, and PFNZ20, with the configuration of ITO/PEDOT/polymer/TPBI/Alq3/Mg:Ag, exhibited good electroluminescence (EL) properties The PLED based on PFNZ10 emitted pure blue light with a low turn‐on voltage of 5.3 V and a high EL efficiency of about 1.93%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5296–5307, 2007