Nanosheet-assembling Hierarchical Zinc Stannate Microspheres for Enhanced Efficiency of Dye-Sensitized Solar Cells

Highlights: • Nanosheet-assembling hierarchical Zn₂SnO₄ microspheres (NHMSs) are proposed. • The NHMSs are used as photoanodes for dye-sensitized solar cells (DSSCs). • The NHMSs based DSSCs enhance the light harvesting within the electrodes. • A high efficiency of 3.43% is achieved with this ternary metal oxide and structure. - Abstract: Nanosheet-assembling hierarchical Zn₂SnO₄ microspheres (NHMSs) are synthesized via one-pot solvothermal route and used as photoanodes for dye-sensitized solar cells (DSSCs). An overall photoconversion efficiency of 3.43% has been achieved with this ternary metal oxide and structure, significantly higher than that derived from dispersed nanosheets (DNSs) electrode (2.06%). The hierarchical Zn₂SnO₄ microsphere structure is proven to be favorable for enhancement of overall dye-sensitized solar cells photoconversion efficiency via (1) the hierarchical Zn₂SnO₄ microspheres can function as efficient light scatters to enhance the light-harvesting efficiency; (2) intersectional contact with one another of the nanosheets of densely packed neighboring microspheres offers the transport channel for fast electron transport, avoiding the high resistance existing in the nanoparticle-based microspheres due to the relatively small interface resistance; (3) these spherical assemblies form large external pores for dye loading, at the same time, provide a "main trunk" for the quick electrolyte diffusion throughout the Zn₂SnO₄ layer in the film