title: Thin film nano solar cells--from device optimization to upscaling.
abstract: Stainless steel based dye solar cells have been upscaled from small, laboratory size test cells of 0.32 cm2 active area to 6 cm x 6 cm "mini-modules" with active areas ca. 15 cm2. Stainless steel works as the photoelectrode substrate whilst the counter electrode is prepared on indium-doped tin oxide coated polyethyleneterephtalate or polyethylenenaphtalate plastic foil (fluorine-doped tin oxide coated glass as a reference). Additional current collector structures were deposited on the counter electrode substrate with inkjet-printing of silver nanoparticle ink in order to reduce the lateral resistance of the plastic foil. Flexible substrates enable roll-to-roll type industrial manufacturing of the cells and the steel's superior conductivity compared to the typical substrate materials such as glass and plastic makes it possible to prepare even substantially larger modules. The best efficiencies obtained this far with the "mini-module" using a stainless steel photoelectrode are 2.5% with a platinum-sputtered indium-doped tin oxide coated polyethyleneterephtalate counter electrode and 3.4% with a thermally platinized fluorine-doped tin oxide coated glass counter electrode. These efficiencies are on the same level than those measured with small cells prepared with similar methods and materials (3.4%-4.7%, depending on configuration, which are amongst the highest reported for this kind of a dye solar cell). Replacing expensive conducting glass with steel and plastic foils as the substrate materials leads also to economical savings in the cell production.
authors.affiliation: Helsinki University of Technology, Advanced Energy Systems, Department of Applied Physics, PO Box 5100, FIN-02015 TKK, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Toivola
authors.forename: Time
authors.initials: T
authors.lastname: Peltola
authors.forename: Kati
authors.initials: K
authors.lastname: Miettunen
authors.forename: Janne
authors.initials: J
authors.lastname: Halme
authors.forename: Peter
authors.initials: P
authors.lastname: Lund