Several highly efficient catalysts for Pt-free and FTO-free counter electrodes of dye-sensitized solar cells

Three nanomaterials, namely, titanium carbide (TiC), tungsten oxide (WO2), and vanadium nitride (VN), are introduced into dye-sensitized solar cells (DSCs) as counter electrode (CE) catalysts to replace the expensive Pt CE. Three kinds of substrates of bare glass (BG), Ti foil, and polyimide (PI) film are applied as F-doped tin oxide (FTO)-free substrates for rigid and flexible DSCs; thus realizing FTO-free and Pt-free CEs simultaneously in the DSC system. A carbon layer is used as an electron collector to replace the expensive FTO conductive layer in the insulative BG and PI film. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization curves are performed to compare the catalytic activities of these CEs for the reduction of triiodide to iodide. The results demonstrate that the DSCs that use TiC, WO2, and VN as CEs on Ti foil have better photovoltaic performance than those that use CEs on traditional FTO glass. Moreover, the TiC, WO2, and VN on the BG substrates show excellent catalytic activities that can match the performance of the CEs on FTO glasses.