Fabrication of cost effective and efficient dye sensitized solar cells with WO₃-TiO₂ nanocomposites as photoanode and MWCNT as Pt-free counter electrode

Tungsten oxide/titanium oxide nanocomposites (nWO₃-TiO₂) with three different WO₃-TiO₂ mass ratios (n = 1%, 3% and 5%) were synthesized and used as a photo-anode to fabricate dye sensitized solar cells (DSSC), in conjunction with multiwall carbon nanotube (MWCNTs) as a platinum free (Pt-free) counter electrode. It was observed that [1%WO₃-TiO₂/N719/MWCNT] DSSC exhibited an efficiency enhancement of about 40% as compared to the conventional TiO₂/dye/Pt solar cell, and 18% efficiency enhancement compared to [1%WO₃-TiO₂/N719/Pt] solar cell. The reduced electron-hole (e, h⁺) recombination in the nWO₃-TiO₂ nanocomposite due to reduced surface trap states, the increased accumulation of electrons at the photo-anode mediated by the photo-excitation of the dye, the efficient electron transportation and increased light absorption can be attributed to the superior performance of [nWO₃-TiO₂/N719/MWCNT] DSSCs in general. Also nWO₃-TiO₂ nanocomposite, when used as a photo-catalyst in the presence of UV radiation for the photo-catalytic degradation of Methylene blue (MB) dye, demonstrated the dye degradation efficiency as high as 99.99%. The enhanced degradation of MB dye further confirms the reduced charge (e, h⁺) recombination and enhanced light absorption, the features essential for a good DSSC. In addition to the photovoltaic and photo-catalytic studies, the morphological and optical characterization of nWO₃-TiO₂ nanocomposite photo-anodes films, the catalytic, electrochemical and electrical characterization of counter electrode and the fabricated DSSCs were carried out.