Ultrafine dice-like anatase TiO2 for highly efficient dye-sensitized solar cells

• Ultrafine dice-like TiO2 has been fabricated on a large scale.
• Dice-like TiO2 film exhibits excellent light scattering due to their aggregations with facet-to-facet joints.
• The pore properties of dice-like TiO2 suppressed the multilayer adsorption of N719 dye in nano-cavity.
• The ultrafine–ultrafine combination contributed an efficiency of 8.66%.

TiO2 is the preferred photoanode material for dye-sensitized solar cells owing to its unique structural and photoelectric characteristics. Because of the weak light scattering, ultrafine TiO2 nanoparticles were regarded as unpromising materials for light scattering layer in dye-sensitized solar cells. We successfully developed a novel nanostructured anatase TiO2 (below 20 nm), i.e., ultrafine dice-like TiO2 with nano-concavity and facet-to-facet joints. Compared with spherical nanostructures with point-to-point joints, the dice-like TiO2 film as photoanode displays some surprising characteristics such as superior light scattering, highly photoelectric conversion performance and inhibiting multilayer dye aggregation. We further fabricate ultrafine–ultrafine anatase TiO2 combination of dice-like TiO2 as scattering layer and commercial TiO2 (P-18) as highly transparent active layer. Because of the bilayer TiO2 combination, the energy conversion efficiency could be enhanced significantly to 8.66%, 36% higher than that of the device with commercial TiO2 nanospheres (200 nm) as scattering layer. The well-balanced combination is a novel practicable strategy to improve the performance of dye-sensitized solar cells.

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