Synthesis and characteristics of Tb-doped Y ₂SiO ₅ nanophosphors and luminescent layer for enhanced photovoltaic cell performance

Nanophosphors based on green emitting terbium doped yttrium silicates with the general formula Y ₂SiO ₅:Tb ³⁺ with a size of 30∼60 nm were synthesized by the hydrothermal method. The prepared nanophosphors were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy and fluorescence spectroscopy. It was found that the nanophosphors crystallize in an X ₁-type monoclinic structure (P2 ₁/c) and absorb UV light from 220 to 300 nm which they then down-convert into visible-light (strong green emission at around 545 nm ( ⁵D ₄ → ⁷F _J)). As TiO ₂-based dye-sensitized solar cells exhibit their maximum incident photon to current efficiency at around 500∼600 nm, the wavelength-modulation characteristics of the nanophosphors can be efficient for dye-sensitized solar cell systems. Therefore, the Y ₂SiO ₅:Tb ³⁺ nanophosphors were introduced into a TiO ₂-based dye-sensitized solar cell and their effects on the performance of the solar cell were investigated.