Incorporation of Mn²⁺ and Co²⁺ to TiO₂ nanoparticles and the performance of dye-sensitized solar cells

Dye-sensitized solar cells were fabricated using (Mn and Co) M-doped TiO₂ electrodes which were successfully synthesized via the hydrothermal method. Furthermore, the effect of Mn²⁺ and Co ²⁺ ions content on the properties of TiO₂ electrodes was studied. The materials were characterized by XRD, TEM/HRTEM, EDS, BET specific surface area (S_BET), pore-size distribution by BJH, UV-Vis Spectroscopy, and their photoconversion efficiencies were evaluated using I-V characterization, IPCE and EIS. X-ray diffraction results reveal both undoped and M-doped TiO₂ structure without any impurity phase. The X-ray diffraction patterns of the (Mn and Co) ions doped TiO₂ is almost the same as that of pure TiO₂, showing that (Mn and Co) have little influence on the formation of anatase titania. The influence of dopant (Mn, Co) ions on band energetics and photoelectrochemical properties of nanostructured TiO₂ electrodes was investigated. The total trap densities were remarkably increased as TiO₂ electrodes were doped with (Mn and Co). Experiment results showed that the content of M-doped TiO₂ plays an important role in the photoelectrochemical properties. The conversion efficiency was decreased with (Mn and Co)-doped TiO₂ electrodes under irradiation of 100 mW/cm² white light due to the high change of flat band edge and the charge recombination which happened related to trap density of TiO₂ electrodes with (Mn and Co) ions doping.