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/cm ². 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%.