Novel synergistic combination of Al/N Co-doped TiO^sub 2^ nanoparticles for highly efficient dye-sensitized solar cells

The present investigation reports the sol-gel synthesis of novel Aluminium/Nitrogen (Al/N)-codoped TiO2 nanoparticles (NPs) and their successful incorporation in dye-sensitized solar cells (DSSCs). The impact of Al doping on the operation of Al/N-doped TiO2 DSSCs has been systematically investigated by varying Al content, while keeping N content constant. The prepared samples have been examined for their crystallite size, surface morphology, chemical state, surface area, optical response and electrical response using various characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Visible spectroscopy (UV–Vis), Scanning electron microscopy (SEM), Tunnelling electron microscopy (TEM) and Electrochemical impedance spectroscopy (EIS). The photovoltaic measurement of all the prepared cells has been performed using solar simulator under 100 mW cm−2 light intensity. A DSSC with 2 wt% Al/N-doped TiO2 NPs shows the best power conversion efficiency (PCE) of 11.08% about 40.78% enhancement in the PCE relative to Degussa P25 based DSSC. The experimental results show that an adequate inclusion of Al and N in TiO2 nanostructure lead to smaller particle size, stabilized structure, increased specific surface area, elevated dye loading, smooth charge carrier separation, enhanced short circuit current density (Jsc) and hence improved PCE of DSSC.