Hierarchical double-layered SnO2 film as a photoanode for dye-sensitized solar cells

Abstract

In this paper, a self-assembling double-layered film consisting of SnO₂ nanosheet arrays as an underlayer and hierarchical SnO₂ microspheres as an overlayer was fabricated via a facile hydrothermal process. The effect of experimental parameters, such as seed layer, acetylacetone, and NH₄F on the morphology of the SnO₂ hierarchical double-layered film was investigated. We disclose that these hierarchical structures are the consequence of the simultaneous processes of growing and recrystallization on the FTO seeded surface and in solution. A formation mechanism was proposed to understand the growth process. The reflectance spectra of SnO₂ double-layered films were also examined.The novel SnO₂-based film shows an enhanced light-to-electricity conversion efficiency compared with a simple composite of SnO₂ nanosheet arrays and microspheres due to their self-assembling capability and favorable nanostructures.