Efficient flexible polymer light emitting diodes with conducting polymer anodes

We report polymer light emitting diodes fabricated on flexible poly(ethyleneterephthalate) substrates coated with a layer of poly(3,4-ethylene-dioxythiophene) : poly(styrenesulfonate) that was lithographically patterned to define the anode structure. A blend of poly(9,9-dioctylfluorene-co-benzothiadiazole) and poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) was then spin-coated on top as the emissive layer and the device was completed by vacuum deposition of a LiF/Al bilayer cathode. The resulting yellow light emitting diodes had typical peak power and current efficiencies of 13.7 lm W⁻¹ and 8.8 cd A⁻¹ respectively, which compare well with values for similar devices fabricated on ITO-coated rigid glass substrates. A maximum luminance in excess of 7300 cd m⁻² was achieved.