Improved dye sensitized solar cell performance in larger cell size by using TiO2 nanotubes

Typical dye sensitized solar cells (DSSCs) exhibit a severe reduction of power conversion efficiency when the cell size is increased. In order to cope with this issue, we have investigated the use of anodized TiO2 nanotubes on Ti foil in combination with the standard TiO2 nanoparticle paste coated anode structure. The presence of nanotubes in the anode structure enabled a significant mitigation of the size-dependent deterioration of the DSSC performance, with a trend of much milder decrease of the efficiency as a function of the cell dimension up to 9 cm(2). The observed improvement is partly attributed to the elimination of fluorine-doped tin oxide glass in the anode structure, as well as the enhanced charge collection via the nanotube coated Ti substrate, resulting from enhanced mechanical and electrical connections and possibly improved light trapping. The introduction of TiO2 nanotubes on the Ti foil substrate led to a substantial improvement of the J(sc) current density. Online supplementary data available from stacks.iop.org/Nano/24/045401/mmedia