Investigations the structural, optical and photovoltaic properties of La doped TiO₂ photoanode based dye sensitized solar cells

Films of TiO₂, La-doped TiO₂ (La–TiO₂), La–TiO₂/TiO₂ and TiO₂/La–TiO₂ are prepared by sol-gel (dip coating) route. The structural properties like phase, grain size, dislocation line density, inter-planner distance, and lattice parameters are calculated by X-ray diffractometer (XRD). All films have anatase phase which is good for solar cells application. Film of La-doped TiO₂/TiO₂ has high grain size. The optical properties like transmittance, absorbance, refractive index, extinction coefficient, dielectric constants and band gap are measured by UV–Vis spectroscopy. The film of La-doped TiO₂/TiO₂ has low bandgap and high transmittance in visible range making it a good candidate for dye sensitized solar cells (DSSCs). DSSCs from these electrodes are prepared by using electrolyte (iodide/tri-iodide) and dye (N719). 1% La–TiO₂/TiO₂ based cell has highest open-circuit voltage (0.74 V), Fill-Factor (0.73), short-circuit current density (6.57 mA/cm²), and efficiency (3.53%) as compared to other cells. Low value of bandgap energy, weak recombination rate, improvement in charge transfer rate is mainly responsible to achieve highest efficiency rate (3.53%).