Improved properties of dye-sensitized solar cells by multifunctional scattering layer of yolk-shell-like TiO2 microspheres

• Novel yolk-shell TiO2 hierarchical microsphere (YSTHS) photoanode was prepared.
• The properties of the DSSC with YSTHS photoanode were significantly improved.
• The increase of Jsc and η were attributed to the enhancement of light scattering and dye adsorption.
• The enhanced light scattering and dye adsorption were ascribed to the unique structure of the YSTHS.

Novel yolk-shell-like TiO2 hierarchical microspheres (YSTHSs) were synthesized by a facile one-pot hydrothermal method. These YSTHSs exhibited excellent light scattering ability and high specific surface area for more dye adsorption. A YSTHSs multifunctional scattering layer was fabricated on top of a conventional TiO2 nanocrystalline layer (T) to form a heterostructure bilayer photoanode (T-YSTHS). The influences of the YSTHSs on the properties of the photoanode and dye-sensitized solar cell (DSSC) were investigated. Studies indicated that by introducing the YSTHSs, the light scattering, dye loading, electron mobility and lifetime of this bilayer photoanode were remarkably increased, resulting in the great enhancement in the short-circuit current density (Jsc) and thus the photoelectric conversion efficiency (PCE) of the DSSCs. This T-YSTHS based DSSC exhibited the maximum Jsc of 16.35 mA cm−2 and PCE of 6.01%, remarkably higher than those of the conventional TiO2 nanocrystalline (2T)-based DSSC by 27.1% and 20.4%, respectively. The remarkable enhancement in Jsc and PCE for the T-YSTHS-based DSSC compared to the 2T-based DSSCs are mainly attributed to the significant enhancement in light scattering and the increase in the specific surface area for dye adsorption due to the unique yolk-shell hierarchical microsphere structure of the YSTHSs.