Figure 4

(a) Scanning electron microscopy (SEM) image of dye-sensitized TiO₂ film incorporated with popcorn NPs. (b) Energy dispersive spectroscopy (EDS) of TiO₂ film incorporated with popcorn NPs. (c) Optical absorption spectra of TiO₂ film with (red curve) or without popcorn NPs (black curve) and dye (N719) sensitized TiO₂ film with (green curve) or without popcorn NPs (blue curve). (d) Relative light absorption change (ΔOA/OA) of dye-sensitized TiO₂ film with popcorn NPs. The thickness of the film is 3 μm. Here, ΔOA(λ)/OA(λ) = (OA_{TiO2+dye+popcorn}(λ) − OA_TiO2+dye(λ))/OA_TiO2+dye(λ), where OA_{TiO2+dye+popcorn}(λ) and OA_TiO2+dye(λ) are the optical absorptions at wavelength λ of dye-sensitized TiO₂ films with and without popcorn NPs, respectively.