Performance of transparent conductors on flexible glass and plastic substrates for thin film photovoltaics

High-performance transparent conductive indium-tin-oxide (ITO) films on flexible glass have been flextested to 25–50k bend cycles without breakage, and with ∼0.1% change in sheet resistance. In contrast, commercial ITO/PET samples undergo ∼50–100% increase in sheet resistance in the same test, indicating that such coatings/substrates may not be acceptable for use in some products or fabrication procedures. The flexible glass substrate enables high-temperature processing, which facilitates the high performance of the coatings. Measurements of the volume resistivity and water vapor transmission rate (WVTR) indicate that Corning ® Willow ® Glass is suitable as a PV substrate material without need for barrier coatings or glass lamination.