Nanocrystalline F-doped tin dioxide materials: texture, morphology and photosensitization with a perylene-substituted organotin

The controlled hydrolysis of fluoro(2-methylbutan-2-oxy)di(pentan-2,4-dionato)tin followed by annealing at 400-550 °C gave conductive mesoporous F-doped SnO₂ materials. The materials consist of a porous network of aggregated nanoparticles, the mesoporosity observed corresponding to the interparticle space. Tuning of the annealing temperature enabled us to prepare materials with surface areas ranging from 70 to 150 m² g⁻¹, with an average pore size comprised between 50 and 100 Å and with a mean particle diameter ranging from 50 to 120 Å. Resistivities as low as 1-2 Ω cm were measured for the sample treated at 550 °C which contained 2-3 at.% of fluorine. This powder reacted with 3-(6-trihex-1-ynylstannylhexyl)perylene to furnish a dye-sensitized F-doped SnO₂ mesoporous materials. An intensity-dependent photocurrent was produced under blue light illumination using the cavity microelectrode (CME) technique. With an aqueous NaBr solution, the photopotential reaches 700 mV, a value slightly higher than that found for an undoped sensitized SnO₂ powder (∼600 mV).