The Investigation of High Quality PEDOT:PSS Film by Multilayer-Processing and Acid Treatment

In this study, we have investigated the performance of multilayer films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) treated with one of the perfluorinated carboxylic acids, named trifluoroacetic acid (TFA). According to the increased density of the PEDOT chain under unit area conditions, the sheet resistance (Rsq) has improved from 300 to 65 Ω/sq through additional processing of PEDOT:PSS from single layer to multilayer. After the further treatment with TFA, however, the Rsq of the multilayer PEDOT:PSS was enhanced to 45 Ω/sq, leading to the decline of film thickness from 400 to 270 nm. Both conductivity and work function based on X-ray photoelectron spectroscopy results have built a breakthrough by double-processing because of the higher density of conductive PEDOT chains and the increase of 0.4 eV alternatives to typical indium tin oxide substrate, respectively. This improvement is contributed to the development of more effective transparent electrodes.