Tailoring the Nanostructure of TiO2. Photoanodes for Efficient Co(II)/Co(III)-Mediated Dye-Sensitized Solar Cells

Novel nanostructured films employing hyperbranched and all-linear TiO2 nanorods have been developed with the aim to overcome the impediments to the diffusion of bulky redox shuttles in photo-electrochemical devices. The porosity of the working electrodes has been tailored by appropriately selecting the nanocrystal building blocks to study how the electrode features affect the electrochemical parameters underlying the charge-transport phenomena and the photovoltaic properties of dye-sensitized solar cells. An optimized combination of porosity, light-harvesting capability, and enhanced electron-transport properties leads to a remarkable improvement of the device efficiency from 1.3% to 8.6%. These results suggest that it is indeed possible to properly design photoanodes based on shape-engineered nanocrystals, which can be suitable for different electrochemical devices such as fuel cells or storage devices employing viscous or quasi-solid electrolytes.