Impedance measurements of nanoporosity in electrodeposited ZnO films for DSSC

Porous ZnO/dye hybrid films have been deposited by cathodic electrodeposition, and their active surface area after dye desorption was evaluated by impedance measurements with the semiconducting electrode polarized in accumulation. Surface area ratios have been deduced for a large number of films from imaginary part Z '' vs. frequency measurements, having a constant rate over the frequency range from 0.5 Hz to >50 Hz. The active surface increased by a factor of roughly 150 per every micron of film with respect to the area of a flat ZnO electrode: this linear relationship held from less than 1 pm up to 9 pm thick films. (c) 2010 Elsevier B.V. All rights reserved.