Performance Enhancement in Dye-Sensitized Solar Cells with Composite Mixtures of TiO2 Nanoparticles and TiO2 Nanotubes

In the present investigation, a new composite nanostructured photoanodes were prepared using TiO2 nanotubes (TNTs) with TiO2 nanoparticles (TNPs). TNPs were synthesized by sol–gel method, and TNTs were prepared through alkali hydrothermal method. Dye-sensitized solar cells (DSSCs) were fabricated with different photoanodes comprising of various ratios of TNTs + TNPs, synthetic indigo dye as photosensitizer, PMII (1-propyl-3-methylimidazolium iodide) as ionic liquid electrolyte and cobalt sulfide as counter electrode. The structures and morphologies of TNPs and TNTs were analyzed through X-ray diffractometer, transmission electron microscope and scanning electron microscopes. The results of the investigation showed that the DSSC-4 made with composite photoanode structure (TNTs/TNPs) (90% of TNPs + 10% of TNTs) had improved photocurrent efficiency (2.11%) than pure TNPs (1.00%) and TNT film (0.78%). Electrochemical impedance spectra revealed that the composite TNTs/TNPs film-based DSSCs possessed the lowest charge-transfer resistances and longest electron lifetime. Hence, it could be concluded that the composite TNTs/TNPs photoanode facilitates the charge transport rate and enhances the efficiencies of DSSCs.