Novel double-layered photoanodes based on porous-hollow TiO2 microspheres and La(OH)3:Yb3+/Er3+ for highly efficient dye-sensitized solar cells

A novel composite double-layer film was developed using TiO 2 /La(OH) 3 :Yb 3+ /Er 3+ nanoparticles (P25/UC) and porous-hollow TiO 2 microspheres (PHTS) for highly efficient dye-sensitized solar cells (DSSCs). P25/UC was used as the first layer and coated onto fluorine-doped tin oxide glass substrate to create a good contact and upconversion effect. The P25/UC layer can absorb and convert infrared light into visible red and green light, increasing light utilization. PHTS has a large size and a high specific surface area, was deposited onto the surface of the P25/UC film to improve the light scattering performance and dye adsorption of solar cells. The P25/UC composite double-layer film (P25/UC + PHTS) achieved the highest short-circuit current density of 20.33 mA/cm 2 and photoelectron conversion efficiency of 8.89% due to the synergistic effect of the upconversion layers and light-scattering layers, which increased by 51.26% and 38.04% compared with that of the pure P25 film photoelectrode.