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

Abstract

Films of TiO 2 , La-doped TiO 2 (La–TiO 2 ), La–TiO 2 /TiO 2 and TiO 2 /La–TiO 2 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 TiO 2 /TiO 2 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 TiO 2 /TiO 2 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–TiO 2 /TiO 2 based cell has highest open-circuit voltage (0.74 V), Fill-Factor (0.73), short-circuit current density (6.57 mA/cm 2 ), 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%). • Bi-layers films of TiO 2 and La-TiO 2 are deposited by sol-gel technique. • 1% La-TiO 2 /TiO 2 film has large grain size, small E g and high transmittance in the visible region. • 1% La-TiO 2 /TiO 2 film has maximum efficiency (3.53%).