Extending the current collector into the nanoporous matrix of dye sensitized electrodes

A new type of high surface area TiO2 electrode for DSSCs is proposed. The new electrode consists of a transparent conductive nanoporous matrix that is coated with a thin layer of TiO2. This design ensures a distance of several nanometers between the TiO2-electrolyte interface and the current collector throughout the nanoporous electrode, in contrast to several micrometers associated with the standard electrode. In addition the new electrode contains inherent screening capability due to the high doping level of the conducting core matrix. Theoretically, this electrode should overcome the collection and image field problems associated with solid-state DSSCs. Using a flat analogue of the new electrode we show that unless the TiO2 coating is thicker than 6 nm, the electrode performance is very low due to fast recombination. Two mechanisms for the thickness effect on the recombination rate, that are proposed, provide new insight to the DSSC operation.