Widely Applicable Coinage Metal Window Electrodes on Flexible Polyester Substrates Applied to Organic Photovoltaics
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- 作者：Helena M. Stec ; Ross A. Hatton
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2012
- 出版时间：November 28, 2012
- 年：2012
- 卷：4
- 期：11
- 页码：6013-6020
- 全文大小：327K
- 年卷期：v.4,no.11(November 28, 2012)
- ISSN：1944-8252
文摘
The fabrication, exceptional properties, and application of 8 nm thick Cu, Ag, Au, and Cu/Ag bilayer electrodes on flexible polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrates is reported. These electrodes are fabricated using a solvent free process in which the plastic surface is chemically modified with a molecular monolayer of thiol and amine terminated alkylsilanes prior to metal deposition. The resulting electrodes have a sheet resistance of 鈮?4 惟 sq鈥?, are exceptionally robust and can be rapidly thermally annealed at 200 掳C to reduce their sheet resistance to 鈮? 惟 sq鈥?. Notably, annealing Au electrodes briefly at 200 掳C causes the surface to revert almost entirely to the {111} face, rendering it ideal as a model electrode for fundamental science and practical application alike. The power conversion efficiency of 1 cm2 organic photovoltaics (OPVs) employing 8 nm Ag and Au films as the hole-extracting window electrode exhibit performance comparable to those on indium鈥搕in oxide, with the advantage that they are resistant to repeated bending through a small radius of curvature and are chemically well-defined. OPVs employing Cu and bilayer Cu:Ag electrodes exhibit inferior performance due to a lower open-circuit voltage and fill factor. Measurements of the interfacial energetics made using the Kelvin probe technique provide insight into the physical reason for this difference. The results show how coinage metal electrodes offer a viable alternative to ITO on flexible substrates for OPVs and highlight the challenges associated with the use of Cu as an electrode material in this context.