Impact of Sn-Sr co-doping on structural, morphological and optical properties of TiO₂ for solar energy conversion applications

In this study, undoped and tin (Sn), strontium (Sr) single and co-doped titanium dioxide (TiO₂) nanoparticles were prepared by the sol-gel technique for potential dye-sensitized solar cell (DSSC) applications. Structural analysis using X-ray diffraction and Laser-Raman spectroscopy substantiated the presence of the anatase phase within a tetragonal crystal system in all prepared samples, with a transition to the rutile phase observed in Sn, Sr-co-doped TiO₂. FTIR spectra indicated peak shifts, demonstrating the interaction between the dopants and TiO₂ lattices. UV-DRS analysis revealed a shift in the optical absorption edge towards the visible region, while the calculated values of the band gap aligned with these findings. Photoluminescence emission intensity was lower in doped TiO₂ samples compared to undoped TiO₂, indicative of improved DSSC efficiency. When employed as active photoanodes in DSSC fabrication, equimolar Sn and Sr co-doped TiO₂ achieved an efficiency of 3.35 %, surpassing the efficiencies of undoped TiO₂ (0.56 %), Sn-doped TiO₂ (1.62 %), and Sr-doped TiO₂ (0.59 %). These findings suggest the potential of co-doping TiO₂ with Sn and Sr to enhance DSSC performance.