Synthesis of LaVO4: Dy3+ luminescent nanostructure and optimization of its performance as down-converter in dye-sensitized solar cells

The effect of downconversion film of LaVO4:Dy3+ nanocrystals, which could absorb UV light and downconvert it to visible light, for increasing the current density of DSSC has been studied. La(CH3CO2)3 as a new source of La was used to synthesis of tetragonal LaVO4:Dy3+ nanocrystals as down shifting material in dye sensitized solar cells by using hydrothermal method. Besides, the optimized Dy3+ concentration and annealing temperature which affect the morphology, particle size, photoluminescence and crystal structure of the produced nanostructures were found for the first time. The as-synthesized products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution field-emission transmission electron microscopy (HRTEM), photoluminescence spectroscopy (PL), scanning electronic microscopy (SEM), spectra energy dispersive analysis of X-ray (EDAX) and ultraviolet–visible (UV–Vis) techniques. The photoluminescence studies of the LaVO4:Dy3+ nanocrystals revealed strong enhancement in emission intensity, when Dy3+ concentration was increased from 0 to 0.08 mmol and annealed at 500 °C. The lattice structure transforms from tetragonal to monoclinic phase subsequent to annealing at 700 and 900 °C. Using this down-conversion material, the current density of solar cell increased by 6.7%, compared to the uncoated solar cell.