Spatially resolved photocurrent mapping of efficient organic solar cells fabricated on a woven mesh electrode

ABSTRACT Flexible organic photovoltaic devices may soon find applications in various fields, such as portable electronics or building‐integrated photovoltaics, occupying market niches that are currently not covered by the prevailing photovoltaic technology based on silicon and other inorganic materials. For these applications, there is an urgent need to replace the commonly used indium tin oxide by transparent and electrically conductive materials that can be processed cost‐effectively by large‐area compatible printing and coating processes. Here, we fabricated P3HT/PCBM organic solar cells with a power conversion efficiency of 3.1% on a flexible, transparent and conductive woven fabric electrode. The electrode is produced by a roll‐to‐roll process and consists of a polymer‐embedded fibre/metal wire grid. Metal wires protrude as little as 5 µm from the electrode plane, providing electrical contact points on a smooth surface suitable for thin film deposition. The use of spatially resolved photocurrent mapping experiments showed a high level of detailed information, with the unexpected indication that there probably exists a maximum in the cell performance versus mesh size opening and that woven fabric electrodes with largest geometrical open area do not necessarily perform better. Copyright © 2012 John Wiley & Sons, Ltd. We present an improved transparent, flexible and conductive electrode based on a woven precision fabric, embedded into a transparent polymer layer with minimal metal wire exposure. Using the benchmark P3HT/PCBM active materials, we demonstrate organic solar cells with power conversion efficiencies of 3.1%. Spatially resolved photocurrent experiments highlight important design criteria for the further optimization of such fabric electrodes.