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 m(2) g(-1)) even after calcinations at 450 degrees 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 similar to 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 similar to 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. (C) 2008 Elsevier B.V. All rights reserved.