Pt-free counter electrodes based on modified screen-printed PEDOT:PSS catalytic layers for dye-sensitized solar cells

One of the most highlighted advantages of dye-sensitized solar cells (DSSCs) consists in the possibility to apply simple and low-cost printing techniques and solution processable materials for their assembling. Here, we report on screen-printed Pt-free counter electrodes (CEs) based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) dispersions with different content of theological agent -hydroxyethyl cellulose (HEC). These PEDOT:PSS dispersions, having measured pseudoplastic and thixotropic theological behaviour, were screen-printed onto FTO glasses. The content of Theological agent in PEDOT:PSS catalytic layers showed an effect on measured thickness, electrochemical properties, specific conductivity and subsequently on the evaluated photovoltaic performance of DSSCs. The PEDOT:PSS CE with the 0.03 wt% of HEC achieved the best electrochemical performance and specific conductivity (80 S cm(-1)), the lowest thickness of 200 nm and transparency in VIS light spectrum over 60%. DSSCs based on this PEDOT:PSS CE reached the highest conversion efficiency of 4.2% which is only approximately 40% lower value than eta = 6.9% evaluated for Pt CE.