Screen-printed Pt counter electrodes exhibiting high catalytic activity

Counter electrodes (CEs) for dye-sensitized solar cells (DSCs) are important for collecting electrons and catalyzing the iodide/tri-iodide reaction. Pt CEs are commonly prepared by magnetron sputtering , which is expensive and requires vacuum conditions. Incorporating the low cost surfactant Span-85 improved the adhesion between the Pt particles and conductive substrate, and allowed Pt-based CEs to be screen-printed. The screen-printed CE was compared with those prepared by dip-coating and spin-coating. Photoelectric conversion efficiencies of 7.30%, 6.96% and 7.03% were achieved for DSCs containing screen-printed, dip-coated and spin-coated CEs, respectively. Optical transmittance measurements, scanning electron microscopy, and film adhesion tests results showed that the surfactant improved film adhesion and increased transmittance, and the screen-printed CEs exhibited comparable transmittance to the dip-coated CEs. Screen-printing resulted in Pt particles being more uniformly distributed on the substrate, when compared with dip-coating or spin-coating. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel-polarization curves showed that the catalytic activity of the screen-printed Pt-based CEs were higher than that of the other CEs. Screen-printing is suitable for realizing the low-cost large-scale production of large Pt-based CEs.