High-Efficiency Electrode Based on Nitrogen-Doped TiO2 Nanofibers for Dye-Sensitized Solar Cells

Highly efficient dye-sensitized solar cell (DSSC) was fabricated using nitrogen-doped TiO2 nanofibers successfully prepared by the electrospinning process followed by hydrothermal treatment. The influence of the nitrogen doping on the morphology, crystallinity and optical behaviour of TiO2 nanofibers were analysed by field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD), X-ray photoemission spectroscopy (XPS), electrochemistry impedance spectra (EIS) and UV-vis spectroscopy analyses. Experimental results evidenced the incorporation of nitrogen atoms into the lattice of TiO2 nanofibers which led to enhancement of the absorption in the visible light region, the charge transfer, electron lifetime and the recombination reaction at the TiO2 photoelectrode/electrolyte interface as compared to the pristine TiO2 nanofibers. It was found that the overall conversion efficiency of DSSCs based on photoanode of N-doped TiO2 nanofiber is significantly higher than DSSCs based on un-doped TiO2 nanofibers. Typically, doping TiO2 nanofibers by nitrogen atoms led to increase the current density from 6.75 to 11.16 mA/cm2. Moreover, the N-doped TiO2 nanofibers revealed energy conversion efficiency of 4.7% which is distinctly high compared to the un-doped nanofibers which showed 1.56%.