Light harvesting enhancement for dye-sensitized solar cells by novel anode containing cauliflower-like TiO2 spheres

Cauliflower-like TiO2 rough spheres, which are about 200 nm large, have greatly enhanced light harvesting efficiency and energy conversion efficiency of dye-sensitized solar cells (DSC), due to their high light scattering effect and large BET surface area (80.7 m2 g−1) even after calcinations at 450 °C for 30 min. The large size TiO2 rough and smooth spheres, produced at different initial temperatures by hydrolysis of Ti(OBu)4 with P105 (EO37PO56EO37) or F68 (EO78PO30EO78) tri-block copolymer as structural agents, have nearly the same diameter of~ 275 nm and strong light scattering effects in the wavelength of 400–750 nm. However, rough spheres have even higher light scattering effect and larger BET surface area than smooth spheres for the roughness of the surface. By adding ~25 wt.% large TiO2 spheres into the over-layer of TiO2 film composed of 20 nm TiO2 particles as light scattering centers, the energy conversion efficiency of the film containing rough spheres reaches 7.36%, much larger than that of smooth spheres (6.25%). From another point of view, the TiO2 rough spheres may have the satisfying ability in other fields of application such as photo-catalysis, drug carriers and so on.