In Situ Synthesized Economical Tungsten Dioxide Imbedded in Mesoporous Carbon for Dye-Sensitized Solar Cells As Counter Electrode Catalyst

Tungsten dioxide imbedded in mesoporous carbon (WO2-MC) was obtained by in situ synthesis and then introduced into dye-sensitized solar cells (DSCs) as a counter electrode (CE) catalyst. Catalytic activity for redox couple regeneration was improved significantly through combining high electrical conductivity and catalytic activity into one material, WO2-MC, in which WO2 served as a catalyst and MC served as an electrical conductor. This has been proved by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The triiodide/iodide-based DSC using WO2-MC as CE showed a high power conversion efficiency (PCE) of 7.76%, which surpassed the performance of the DSC using traditional Pt CE (7.55%). In addition, the WO2-MC and WO2 nanorods exhibited higher catalytic activity than Pt for the regeneration of a new organic redox couple, di-5-(1-methyltetrazole) disulfide/5-mercapto-1-methyltetrazole N-tetramethylammonium salt (T-2/T-). The PCE of the T-2/T--based DSCs using WO2-MC, WO2, and Pt were 5.22, 4.66, and 3.09%, respectively.