Effects of hydrochloric acid treatment of TiO2 nanoparticles/nanofibers bilayer film on the photovoltaic properties of dye-sensitized solar cells

The TiO 2 nanoparticles/nanofibers bilayer film has been fabricated via spin coating and electrospinning followed by calcination. The TiO 2 bilayer film with thickness of about 6.0   μm is composed of anatase TiO 2 phase. Dye-sensitized solar cells (DSSC) were assembled by hydrochloric acid (HCl) treated TiO 2 film. The results of the photocurrent action spectra, electrochemical impedance spectroscopy (EIS), and I – V curves showed that each photovoltaic parameter of DSSC increased with the concentration of HCl increasing, and reached a maximum value and afterwards decreased. The maximum incident monochromatic photo-to-electron conversion efficiency (at 350   nm) and maximum overall conversion efficiency ( η ) of 0.05   M HCl treated TiO 2 based DSSC were enhanced to 48.0% and 4.75%, which were respectively increased by 14% and 6.3% than those of DSSC based on untreated TiO 2 film.