Fabrication of High Efficiency Dye-Sensitised Solar Cell with Zirconia-Doped TiO2 Nanoparticle and Nanowire Composite Photoanode Film

Dye-sensitised solar cells (DSSCs) were fabricated based on coumarin NKX-2700 dye-sensitised zirconia-doped TiO2 nanoparticle and nanowire composite photoanode film and quasi-solid-state electrolyte, sandwiched together with cobalt sulfide-coated counter electrode. Novel photoanodes were prepared using composite mixtures of 90wt-% TiO2 nanoparticles+10wt-% TiO2 nanowires (TNPWs) as base material and zirconia as doping metal. Hafnium oxide (HfO2) was applied on the zirconia-doped TNPWs (zirconia/TNPWs) film structure as a blocking layer. TiO2 nanoparticles, TiO2 nanowires, and zirconia/TNPWs were characterised by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The sensitising organic dye coumarin, NKX-2700, displayed maximum absorption wavelength ((max)) at 525nm, which could be observed from the UV-visible spectrum. DSSC-1 built with zirconia/TNPWs-doped photoanode with blocking layer revealed enhanced photo-current efficiency (PCE) as compared with other DSSCs and illustrated photovoltaic parameters: short circuit current J(SC)=20mAm(-2), open circuit voltage (V-OC=730mV, fill factor (FF)=68%, and PCE ()=9.93%. The electron transport and charge recombination behaviours of DSSCs were investigated by electrochemical impedance spectroscopy and the results exhibited that DSSC-1 possessed the lowest charge transfer resistance (R-rec) and longest electron lifetime ((rec)) compared with other DSSCs. Therefore, from the present investigation, it could be concluded that the improved performance of DSSC-1 is ascribed to the zirconia/TNPWs-doped photoanode with the blocking layer increasing the short circuit current, electron transport, and suppressing the recombination of charge carriers at the photoanode/dye/electrolyte interface.