Improved stability and enhanced efficiency of dye sensitized solar cells by using europium doped yttrium vanadate down-shifting nanophosphor

Through detailed experiments, it has been deduced that ultraviolet (UV) light is a major factor in the degradation of dye-sensitized solar cell (DSSC) performance due to generation of surface defects in nanoporous TiO2 and dye structural modification with free radical formation. We describe a simple spray deposition method to coat europium doped yttrium vanadate (YVO4:Eu3+) down-shifting (DS) phosphor nanoparticles (NPs) on the front side of DSSCs in order to enhance photocurrent and mitigate UV induced degradation. The nanophosphor provides an enhancement in short-wavelength spectral response of solar cells, and long-term stability is also improved under illumination, due to down-shifting of high energy UV photons to the visible region. Our observations demonstrate that the DS nanophosphor layer can be used as an optical filter with visible light transmission and UV light absorption, through placement on the front surface of DSSCs to provide stability, as well as for improving the performance.