In-situ doping and post-treatments modulate the photoelectrical properties and stability of electropolymerization poly(3,4-ethylenedioxythiophene)

Poly(3,4-ethylenedioxythiophene) (PEDOT) has been widely used in electrode materials, electrochromic materials, biosensors, supercapacitor, and solar cells, etc. In these applications, high requirement for the stability of PEDOT is indispensable. This study focused on enhancing the stability of electro-polymerized PEDOT electrodes by in-situ doping and solvent treatment in order to reduce the dissolution products of PEDOT under photoelectric conditions. The post-treatment was a combination of soaking and/or rising with deionized water, anhydrous ethanol and sulfuric acid solution (pH = 2) for different times. Among them, the sample rinsed successively with anhydrous ethanol and deionized water was the most effective post-treatment method, which can reduce the dissolution amount by 35%. Through doping para-toluenesulfonic acid (TsOH), the dissolution amount was further decreased by 58%. The surface hydrophobicity of PEDOT was increased from 23 degrees to 38 degrees after doping with TsOH, which was beneficial to the stability of PEDOT. Except for sodium polystyrene sulfonate (PSS) doping, the photocurrent response of PEDOT can be increased by doping other selected substances. Specially, the photocurrent response of TsOH-PEDOT was increased by 59%. There is a certain negative correlation between dissolution amount and the photocurrent response, suggesting less dissolution is conductive to maintaining high photoelectric performance.