Nanostructured Carbon-TiO₂ Shells Onto Silica Beads as a Promising Candidate for the Alternative Photoanode in Dye-Sensitized Solar Cells

We report a novel strategy to enhance the performance of dye-sensitized solar cells (DSSCs) by incorporating small amounts of nanostructured carbon-TiO₂ beads into the photoanode. A commercially available triblock copolymer, Pluronic P123, containing TiO₂ precursors in the hydrophilic domains was coated onto SiO₂ nanospheres and converted into graphitic carbons by thermal treatment in Ar atmosphere. By distributing carbon species with the size of ∼50 nm throughout the TiO₂ photoanode, the power conversion efficiency of DSSC cell was improved by up to 10.1% due to the increase in the value of short circuit current compared with that of neat TiO₂ photoanode based DSSC cell, which was confirmed by photocurrent–voltage profile and incident photon-to-current conversion efficiency. The introduction of carbons into TiO₂ photoanode in DSSCs led to not only the decrease in the series resistance and the charge transfer resistance of photoanode but also the increase in lifetime of photoinjected electrons as evidenced by electrochemical impedance spectroscopy. The stability of the DSSC cells equipped with the carbon-TiO₂ beads integrated photoanode was also prominent. It suggests a simple fabrication protocol of an alternative zero-dimensional graphitic TiO₂ photoanodes that can replace the conventional TiO₂ photoanode.