Unraveling the Enhanced Electrical Conductivity of PEDOT:PSS Thin Films for ITO-Free Organic Photovoltaics

We present the structure and the optical and mechanical properties of highly conductive PEDOT:PSS (1:2.5 wt%, PH1000) thin films fabricated with and without an immersion treatment process using a solution containing 67% ethylene glycol and 33% hexafluoro-isopropyl alcohol, by volume. The enhanced electrical conductivity of the PEDOT:PSS thin films originated from the formation of a conducting PEDOT network in combination with an increased electron concentration due to the conformational changes in the PEDOT chains. The modified PEDOT:PSS thin film was used as a transparent anode electrode for P3HT:PCBM blended film-based photovoltaics, resulting in a power conversion efficiency of 3.28% under 1-sun illumination.