Dual functions of YF3:Eu3+ for improving photovoltaic performance of dye-sensitized solar cells

In order to enhance the photovoltaic performance of dye-sensitized solar cell (DSSC), a novel design is demonstrated by introducing rare-earth compound europium ion doped yttrium fluoride (YF₃:Eu³⁺) in TiO₂ film in the DSSC. As a conversion luminescence medium, YF₃:Eu³⁺ transfers ultraviolet light to visible light via down-conversion, and increases incident harvest and photocurrent of DSSC. As a p-type dopant, Eu³⁺ elevates the Fermi level of TiO₂ film and thus heightens photovoltage of the DSSC. The conversion luminescence and p-type doping effect are demonstrated by photoluminescence spectra and Mott-Schottky plots. When the ratio of YF₃:Eu³⁺/TiO₂ in the doping layer is optimized as 5 wt.%, the light-to-electric energy conversion efficiency of the DSSC reaches 7.74%, which is increased by 32% compared to that of the DSSC without YF₃:Eu³⁺ doping. Double functions of doped rare-earth compound provide a new route for enhancing the photovoltaic performance of solar cells.