Boron-Modified TiO2 Microsphere With Enhanced Photovoltaic Performance

Nanotubes-assembled rutile TiO₂ microspheres were successful prepared by a facile two-step hydrothermal approach in the presence of sodium metaborate tetrahydrate. SEM and FESEM micrographs revaled that the addition of boron enrichs the assembled nanorodes with a reduced diameter during hydrothermal process, probably result from the increased crystal defects induced more reaction sites for crystal growth after introduction of lots of boron compound. A slight shift to the left and weakened intensity of the diffraction peaks appeared in XRD pattern without obvious peaks for diboron trioxide evidenced the obtained rutile TiO₂ accompanied with boron at interstitial sites. When applied to the photoanode of dye-sensitized solar cell, the photovoltaic device achieved a favorable photoelectricity conversion efficiency of 3%, which was 74% higher than that of the non-modified TiO₂. Further investigation on the cells’ electrochemical properties were adopted by the impedance spectroscopy, which showed a longer electron lifetime and lower electron transfer rate at photoanode/dye/electrolyte interface compared to the pure TiO₂ sample.