White Electroluminescence from a Single Fluorene-Based Copolymer

White light emitting polymers were synthesized through incorporating of low-band gap red light emitting 4,7-di(4-hexyl-thien-2-yl)-2,1,3-benzothiadiazole (DHTBT) moieties into the backbone of a blue-light-emitting poly(9,9-dioctylfluorene) (PFO). Incomplete energy transfer from the blue electroluminescent PFO backbone to the red light emitting unit occurred by carefully controlling the relative content of the low-band gap unit DHTBT in the resulting polymers. Pure white light electroluminescence from a single polymer has been obtained in a device with a configuration of ITO/PVK/polymer/Ba/Al.The highest external quantum efficiency is 1.04% at the luminance of 249 cd/m2 for the white emitting polymer with color coordinates (0.30, 0.35) very close to the CIE coordinates for National Television System Committee (NTSC) standard white-light emission (0.33,0.33).