DSSC photoanodes fabricated with mesoporous TiO₂ hollow spheres

To enhance solar energy efficiency of a dye-sensitized solar cell (DSSC), high crystallinity mesoporous TiO₂ hollow spheres (MHS-TiO ₂) have been coated on the DSSC photoanode. The MHS-TiO₂ was prepared by calcination of the Ti(OBu)₄ coated mesoporous carbon hollow spheres at temperature of 873 K. Observations by XRD, FE-SEM, TEM, and HR-TEM suggest that the MHS-TiO₂ is composed of mainly fine anatase nano structures. The specific absorption edge and band gap of the MHS-TiO ₂ determined by diffuse reflectance ultraviolet-visible spectroscopy are 200-400 run and 3.44 eV, respectively. By X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), it is found that the MHS-TiO₂ possesses Ti-0 and Ti-(0)-Ti bond distances of 1.98 and 3.07 å with coordination numbers of 2.9 and 0.7, respectively. The current-voltage (I-V) curves of the DSSC utilizing the MHS-TiO₂ photoanodes were determined with an AM 1.5G solar simulator. Notably, the photovoltaic performances of the DSSC are 0.714 V in the open-circuit voltage, 2.52 mA-cm^-2 in the short-circuit current density, and 0.666 in the fill factor, and a better conversion efficiency (1.2%) is obtained.