White and Red Electroluminescence from a Single Copolymers of Fluorene and 4-Thienyl-2,1,3-Benzothiadiazole
We have developed efficient pure white- and red-light-emitting polymers through incorporating of low-band gap orange-light-emitting 4-thienyl-2,1,3-benzothiadiazole (BTT) moieties into the backbone of a blue-light-emitting poly(9,9-dioctylfluorene) (PFO). Partial or complete energy transfer from the blue electroluminescent PFO backbone to the orange- light-emitting unit occurred by carefully controlling the relative content of the low-band gap unit BTT in the resulting polymers. Pure white- and red-light electroluminescence from a single polymer has been obtained in a device with a configuration of ITO/PEDOT:PSS/polymer/Ca/Al. The highest external quantum efficiency is 2.4% with luminous efficiency 2.20 cd/A at the luminance of 793 cd/m2 for the red-light emitting copolymer PFO-BTT with emission peak at 607 nm for 15mol% BTT content, the highest external quantum efficiency is 0.5% at the luminance of 81 cd/m2 for the white emitting polymer with color coordinates (0.34, 0.34) very close to the CIE coordinates for National Television System Committee (NTSC) standard white-light emission (0.33,0.33).
Guojun Zhang and Jessica Xu
Q. Hou et al., "White and Red Electroluminescence from a Single Copolymers of Fluorene and 4-Thienyl-2,1,3-Benzothiadiazole", Advanced Materials Research, Vols. 160-162, pp. 762-767, 2011