Enhancement of dye sensitized solar cell efficiency through introducing concurrent upconversion/downconversion core/shell nanoparticles as spectral converters

Extending the spectral absorption of dye-sensitized solar cells from the visible into near-infrared and ultra-violet range enables the minimization of non-absorption loss of solar photons. Here, we report a viable strategy to implement simultaneously near-infrared upconversion and ultra-violet downconversion for dye-sensitized solar cells through constructing a type of upconversion-core/downconversion-shell-structured nanoparticles. For the first time, NaYF4:20%Yb,2%Er@NaYF4:7%Eu core/shell nanoparticles are applied to TiO2 photoanode for fabricating near-infrared/ultra-violet-enabled dye-sensitized solar cell devices. The incorporation of designed nanoparticles into TiO2 photoanode of dye-sensitized solar cells achieves high efficiency of 7.664% under one sun illumination, increasing the power conversion efficiency by about 13.95%. We confirm that the enhancement of overall efficiency includes 4.82% upconversion contribution, 7.58% downconversion function and 1.55% scattering effect. Our strategy opens the path for further broadening the solar spectral use to improve the performance of photovoltaic devices.