Preparation of YbF3-Ho@TiO2 core–shell sub-microcrystal spheres and their application to the electrode of dye-sensitized solar cells

Abstract

A double-layer heterostructured photoanode for dye-sensitized solar cells (DSSCs) was designed using YbF₃-Ho@TiO₂ core–shell sub-microcrystal sphere compounds. This heterostructured photoanode possessed efficient light scattering effects due to the sub-microcrystal sphere morphology and additional near infrared light harvesting via the upconversion function of YbF₃-Ho@TiO₂. More importantly, this heterostructured photoanode could facilitate the charge separation, suppress the recombination process of the injected electrons with I₃⁻ at the photoanode/dye/electrolyte interface and prolong the lifetime of electrons. Therefore, DSSCs based on the photoanode with a double-layer heterostructure showed a higher short-circuit photocurrent density of 17.06 mA cm⁻² and an overall conversion efficiency of 7.73%, which indicated a 17% enhancement in the photocurrent and 21% improvement in the energy conversion efficiency compared with the reference TiO₂ DSSCs (14.56 mA cm⁻², 6.39%).