A dual-functional NaLuF4:Yb3+/Er3+ material for enhancing photon harvesting in dye-sensitized solar cells

A new strategy to improve the efficiency of dye-sensitized solar cells by using the external near-infrared light harvesting and light-scattering dual-functional upconversion (UC) material NaLuF4:Yb3+/Er3+ is proposed. The photoluminescence spectra of NaLuF4:Yb3+/Er3+ showed the emission of green and red light, and these luminescence bands coincided well with the absorption wavelength of N719 dye. A small amount of UC material could serve as a good scattering material in photoelectrodes. The photoelectric conversion efficiency reaches 7.58% at a concentration of 5 wt% of UC (weight ratio of UC to TiO2), which is 27.18% higher than that of P25 photoanode (5.96%) with similar thickness. This finding may be attributed to the UC luminescence and light scattering properties of the UC material.