Enhancing the performance of dye-sensitized solar cells based on TiO2 nanotube/nanoparticle composite photoanodes

Improved efficiencies in quasi solid-state and liquid state dye-sensitized solar cells (DSSCs) are achieved by constructing TiO2-based photoanodes with nanostructures of nanotubes (NTs) and nanoparticles (NPs). High surface area, high quality, and good crystallinity of TiO2 NTs were synthesized through a simple reflux method by using commercial P25 NPs as a precursor. The highest conversion efficiency was investigated while the composite photoanode composed of the mixture of 10% (v/v) NTs in NPs, where assembled DSSCs exhibited the conversion efficiency of 2.4% in PEGDME-based electrolyte and 10.27% in DMPII-based liquid electrolyte, with TiO2 composite thickness of 6 μm and 12 μm, respectively, which showed improved conversion efficiency by 20.6% and 10.5% as compared to that of pure TiO2 NP DSSC. Electrochemical impedance spectra (EIS) demonstrate that TiO2 NTs are beneficial to improve the electron transport property as well as possess high charge collection and light harvesting and thus lead to the enhancement of the conversion efficiency.