Screen-printed PEDOT:PSS/halloysite counter electrodes for dye-sensitized solar cells

Abstract

In this work, water-based and viscous screen-printing inks composed of conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) and insulating halloysite nanotubes as a filler (HNTs) with different organic additives were prepared by simply homogenization process. PEDOT:PSS/HNTs inks were screen-printed onto FTO substrates and were used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Incorporation of HNTs leads to a significant increase in ink thermal stability evaluated by TGA. XPS results indicate that simple homogenization process of PEDOT:PSS and HNTs led to the formation of compact PEDOT:PSS/HNTs nanocomposite structure where components are linked by physical interactions. Screen-printed PEDOT:PSS/HNTs CEs with 1 wt% of HNTs reached the highest conductivity (381 S/cm). Moreover, the positive effect of HNTs filler in CEs was confirmed by electrochemical measurements (CV and EIS). DSSCs with screen-printed PEDOT:PSS/HNTs CEs have overall better photovoltaic properties with ≈15% increase in the conversion efficiency (η = 4.5%) compared to PEDOT:PSS CEs.