Hierarchical submicroflowers assembled from ultrathin anatase TiO2 nanosheets as light scattering centers in TiO2 photoanodes for dye-sensitized solar cells

Hierarchical TiO2 submicroflowers (HTFs) were mixed with anatase TiO2 nanoparticles (TNPs) to fabricate efficient photoanodes for dye-sensitized solar cells (DSSCs). HTFs with high specific surface area (98 m(2)g(-1)) and favorable dimension (similar to 660 nm) facilitate dye loading and light scattering of photoanodes, boosting the light harvesting capability of DSSCs. Moreover, due to the high crystallinity and reduced defects or grain boundaries, the HTFs embedded in the photoanodes act as efficient conductive pathways for charges. With excessive incorporation of HTFs, on the other hand, inevitable shrink of HTFs after calcination causes poor connectivity of TiO2 network and even cracks in the photoanodes, deteriorating the charge collection capability of DSSCs. As a result, a balance should be made between optical and photoelectrochemical characteristics of photoanodes via HTF introduction. The DSSC based on 10 wt % HTFs embedded photoanode exhibits the highest power conversion efficiency of 6.4%, which is 52.4% higher than that of DSSCs with TNP-based photoanodes. (C) 2018 Elsevier B.V. All rights reserved.