Enhancing the performance of dye-sensitized solar cells based on organic dye sensitized TiO2 nanoparticles/nanowires composite photoanodes with ionic liquid electrolyte

Dye-sensitized solar cells (DSSCs) are attractive solar cell option because of their relatively low manufacturing cost and simple process technology. In the present investigation, photoanodes were prepared using TiO2 nanoparticles (TNPs), TiO2 nanowires (TNWs) and its various composites (TNPWs). TNPs and TNWs were prepared by sol-gel/hydrothermal methods and mixed at various weight ratios (100 wt.% TNPs without TNWs), (90 wt.% TNPs with 10 wt.% TNWs), (50 wt.% TNPs with 50 wt.% TNWs), (10 wt.% TNPs with 90 wt.% TNWs); (total weight 5 g). DSSCs were fabricated based on Indigo dye sensitized photoanodes with ionic liquid electrolyte PMII (1-propyl-3-methylimmidazolium iodide) and cobalt sulfide coated counter electrode. The crystalline structure and morphology of TNPs and TNWs were characterized by X-ray diffraction (XRD) and electron microscopes. Photovoltaic study revealed that DSSC-4 made with composite photoanode (10 wt.% TNWs + 90 wt.% TNPs) had highest photo conversion efficiency (PCE) of 2.27% as compared to DSSC-2 (made with pure TNPs photoanode; eta = 1.00%) and DSSC-3 (pure TNWs photoanode; eta = 0.77%). Electrochemical impedance spectra (EIS) demonstrated that composite TNPWs photoanodes are beneficial to improve the electron transport property as well as possessed high charge collection efficiency and light harvesting, which steer to the enhancement of PCE of DSSCs. (C) 2014 Elsevier Ltd. All rights reserved.