Dye-sensitized photocells with meso-macroporous TiO2 film electrodes

Meso-macroporous anatase TiO2 films, described in a previous work, have been used for the first time as electrodes for dye-sensitized photoelectrochemical cells. The mesopores provide a large surface area that is favorable for efficient light absorption, and the macropores serve as pathways for diffusion of electroactive agents (EAAs). Although the introduction of macropores led to an improvement in the magnitude of the short-circuit photocurrent (J(sc)), electron recombination on the SnO2 substrate surface at the bottom of the macropores deteriorated the open-circuit voltage (V-oc). This unfavorable process has been depressed by applying a thin (200 to 300 nm) TiO2 film between the meso-macroporous film and the SnO2 substrate, to obtain finally a dye-sensitized photoelectrode with a V-oc nearly identical with, and a J(sc) superior to, the values for a conventional porous TiO2 film electrode.