Flexible organic light-emitting diode with a conductive polymer electrode

We report on a flexible organic light-emitting diode (FOLED) prepared by using a poly(3,4-ethylenedioxythiophene) (PEDOT) anode formed via in-situ polymerization of ethylenedioxythiophene (EDOT) on a polyethersulfone (PES) substrate. Ferric p-toluene sulfonate (FTS) was used as a dopant, and N,N-dimethylacetamide (DMAc) was added to enhance the anode properties. The PEDOT:FTS film polymerized in the presence of DMAc (DMAc-PEDOT:FTS) exhibited better performance than those polymerized without DMAc (Normal-PEDOT:FTS) in terms of both optical transmittance and surface resistance, and the DMAc-PEDOT:FTS film gave a work function of 4.67 eV which is 0.3 eV higher than that of the Normal-PEDOT:FTS film. Optical transmittance and surface resistance of the DMAc-PEDOT:FTS films could be controlled to be 52–87% and 130–390 Ω/sq, respectively. When an optimized DMAc-PEDOT:FTS film was employed as an anode, the Alq3 [(8-hydroxy-quinolinato)-aluminium] based FOLED device exhibited 30% higher luminous efficiency and more than 20 times higher max luminance than the device with the Normal-PEDOT:FTS anode.