Application of TiO2 hollow microspheres incorporated with up-conversion NaYF4:Yb3+, Er3+ nanoparticles and commercial available carbon counter electrodes in dye-sensitized solar cells

In this work, the up-conversion phosphor NaYF 4 :Yb 3+ , Er 3+ nanocrystalline mixed with P 25 and TiO 2 hollow microspheres with high light scattering ability were fabricated as electrode for dye-sensitized solar cells (DSSCs). Meanwhile, we take advantage of the low cost feature of the carbon counter electrode to replace the precious metal Platinum (Pt) of DSSCs. SEM results show that the well-dispersed TiO 2 hollow microspheres size is 1.5 μm with surface consisting of a large number of rice-like nanorods. The particle size of the as-prepared NaYF 4 :Yb 3+ , Er 3+ nanoparticles is about 80 nm. The Photocurrent-Voltage curve of P 25 /NaYF 4 :Yb 3+ , Er 3+ cell under 980 nm infrared light has an obvious infrared photoresponse. The fabricated DSSCs using NaYF 4 :Yb 3+ , Er 3+ achieves power conversion efficiency (PCE) of 5.27% under one sun illumination, which shows an increase of 16% when compared with the benchmark P 25 cell (4.55%). In addition, the optimized DSSC using TiO 2 hollow microspheres as the top scattering layers with NaYF 4 :Yb 3+ , Er 3+ /P 25 exhibits a prominent PCE of 6.23%, which shows a 37% increase in conversion efficiency when compared with the commercial P 25 cell (4.55%). The increase in conversion efficiency should be contributed to the dual effects of the enhanced light harvesting of up-conversion NaYF 4 :Yb 3+ , Er 3+ and light utilization of the top light scattering TiO 2 hollow microsphere.