Phosphor positioning for effective wavelength conversion in dye-sensitized solar cells

Abstract

In the present study, the wavelength conversion effect resulting from phosphor’s position in dye-sensitized solar cells (DSSCs) is investigated. Integrating phosphor (in particular, t-LaVO4:Dy3+ downshifting phosphor) into DSSCs enables C106-organometallic dye to generate excess electrons because of the wavelength conversion process from ultraviolet to visible light. The coupling of downshifting phosphors with ultraviolet wavelengths inside DSSCs induces increasing quantities of visible light, which can be absorbed into C106 dye; this phenomenon leads to an increase in the energy conversion efficiency of DSSCs. We observe that the wavelength conversion effect depends on the position of phosphor inside a DSSCs. The methods of introducing downshifting t-LaVO4:Dy3+ phosphor crystals onto a TiO2 film electrode and dispersing these crystals into an iodide electrolyte produce an increase in the overall solar-to-electrical energy conversion efficiency (η) to 9.6% and 9.5%, respectively, from 9.2% for DSSCs without phosphor components. DSSCs with phosphor both positioned on the TiO2 film and dispersed into the iodide electrolyte show a highly increased overall efficiency (η) of 9.9%. For this study, the correlation between phosphor positioning and the wavelength conversion effect inside a DSSCs is comparatively investigated, and we suggest that the results of this study represent the most viable strategy to maximally utilize the solar spectrum.