Pure blue light-emitting fluorene-based conjugated polymer with excellent thermal, photophysical, and electroluminescent properties

Abstract

A functionalized polyfluorene (FPF) with dendritic carbazole and oxadiazole side chains have been successfully designed, synthesized, and characterized. The weight-average molecular weight (M w) and number-average molecular weight (M n) were measured by gel permeation chromatography (GPC) to be 71280 and 31185, respectively. The FPF is thermally stable with high decomposition temperature (T d = 495 °C) and glass transition temperature (T g = 160 °C), and show good solubility in organic solvents, such as N,N-dimethyl formamide, tetrahydrofuran, CHCl3, and toluene. The photoluminescent and electroluminescent (EL) emissions and Commission Internationale de L’Eclairage coordinates indicated pure blue light emission of FPF and its device. The luminance–voltage (L–V) and current density–voltage (J–V) characteristics of the devices based on FPF indicated typical diode characteristics with a maximum luminance of 980 cd/m2 at a drive voltage of 13.0 V, a maximum current density of 726 mA/cm2, and a turn-on voltage of 8.54 V. The maximum EL efficiency of the device based on FPF was measured to be 0.46 % at the current density of 12.5 mA/cm2. These results indicate that the FPF polymer could be a promising candidate for pure blue light-emitting polymer with excellent thermal, photophysical, and electroluminescent properties.