Sol-hydrothermal synthesis of TiO₂: Sm³⁺nanoparticles and their enhanced photovoltaic properties

A down-conversion (DC) photoelectrode of TiO₂:Sm³⁺nanocrystals synthesized by sol-hydrothermal method was introduced on dye-sensitized solar cells (DSSCs) to investigate the effect of DC nanocrystals in DSSCs. X-ray diffraction (XRD), energy disperse spectroscopy (EDS) and Brunauer-Emmet-Teller (BET) analysis were employed to characterize the structure, composition and pore size of the synthesized nanocrystals, respectively. The fluorescence spectroscopy indicates that the DC photoelectrode has the capability to convert ultraviolet light into visible light, which can be effectively absorbed by the sensitizer N719. The absorbed light will then be converted into electricity accordingly. Photovoltaic properties of the new DSSCs doped with 0.5 up to 1.5 mol% of samarium were investigated. The photoelectric performances show that the short-circuit current density (J_sc) of DSSCs based on a 1 mol% Sm³⁺doped TiO₂photoanode reached 16.71 mA/cm², enhanced by approximately 25.07% compared to that of the cell based on pure TiO₂photoelectrode. The power conversion efficiency (η) of the DSSCs was also increased by 16.7%. The enhancement can be attributed to the DC effect of TiO₂:Sm³⁺nanocrystals.