Anatase TiO2 hollow spheres embedded TiO2 nanocrystalline photoanode for dye-sensitized solar cells

The anatase TiO2 hollow spheres with diameter of 500 nm and shell thickness of 25 nm are embedded in P25 TiO2 nanocrystalline photoanodes to improve the light scattering ability of the photoanode. Photoanodes embedded with different contents of TiO2 hollow spheres are prepared and the profiles of the photoanodes are systematically characterized. It is found that the morphologies of the photoanodes were modified by the TiO2 hollow spheres. With increasing the TiO2 hollow spheres’ contents, the light scattering ability of the modified photoanodes is effectively improved, while the dye adsorption decreases. By optimizing the TiO2 hollow spheres’ content in TiO2 nanocrystalline, a higher performance of the DSSC (Jsc = 16 mA cm−2, Voc = 0.72 V, FF = 0.648 and η = 7.59%) is obtained compared with the pure TiO2 nanocrystalline DSSC (Jsc = 13.96 mA cm−2, Voc = 0.686 V, FF = 0.684 and η = 6.67%, measured at 98.3 mW cm−2, AM1.5). The improved performance is mainly due to the enhanced light scattering by the TiO2 hollow spheres. The open circuit voltage of the hollow spheres modified DSSCs is higher than that of the DSSC with pure P25 photoanode, which can be attributed to the fact that TiO2 hollow spheres substitute of the TiO2 nanocrystallines and reduce the interface recombination by decreasing the surface charge trap-site density of the photoanodes.