Enhancing photoelectrical performance of dye–sensitized solar cell by doping SrTiO₃:Sm³⁺@SiO₂ core–shell nanoparticles in the photoanode

Highlights: •A new SrTiO₃:Sm³⁺@SiO₂ core–shell nanoparticles was synthesized. •The effect of SrTiO₃:Sm³⁺@SiO₂ doped in the photoanode was investigated. •SrTiO₃:Sm³⁺@SiO₂ doped in photoanode appeared the higher efficiency. •Down-conversion, suppressing recombination and light scattering were explained. -- Abstract: SrTiO₃:Sm³⁺@SiO₂ (STS@SiO₂) core–shell nanoparticles were fabricated by Stöber method after a simple hydrothermal process and then being introduced into the TiO₂ photoanode to assemble dye–sensitized solar cells (DSSCs). X–ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM) analysis confirmed the formation of core–shell nanoparticles with cubic structured SrTiO₃:Sm³⁺ (STS) as core, SiO₂ as shell. The photo–fluorescence (PL) and ultraviolet–visible (UV–Vis) absorption spectra of photoanodes with different STS@SiO₂ content indicate a down–conversion from ultraviolet light to visible light which matched the strong absorbing region of the N719 dye. Compared with the pure TiO₂ and STS doped TiO₂ photoanode, STS@SiO₂ doped TiO₂ photoanode showed a greater photovoltaic efficiency. The photoelectric conversion efficiency (η) of 5.07% for 10 wt% STS@SiO₂ doped TiO₂–based DSSC was higher than that of 3.72% for pure TiO₂–based DSSC and 4.29% for 10 wt% STS doped TiO₂–based DSSC. This phenomenon could be explained by STS@SiO₂ core–shell nanoparticles' triple ability to extend spectral response range to the ultraviolet region, suppress the recombination of electron–electrolyte and lengthen the light traveling distance in the photoanode by the scattering