Flexible transparent electrodes are a key element in the development of thin films photovoltaics and in particular organic photovoltaic (OPV) cells. The fabrication of transparent conductors is currently realized with thin films of transparent conductive oxides (TCOs), and in particular indium tin oxide (ITO). However, the as-made ITO transparent electrodes suffer from limitations like a costly fabrication process, brittleness and risky price of indium.The use of solution-processable electrodes would be a promising alternative since it would afford large area, low-cost and low temperature deposition method. Recently, extensive efforts have been focused on new transparent electrodes based on nanomaterials. In particular, the use of metallic nanowires appears as a very promising route.We have developed an optimized solution process to synthesize high performance metallic nanowires, mainly based on silver and copper. The purified nanowires are then spray-coated at low temperature (< 80C) on various substrates to form percolative random networks. Very good performances were obtained, e.g.less than 25 ohm.sq-1at 90% transparency on plastic substrates, and excellent flexibility was achieved even on very thin films (< 2 microns). In some cases, nanowires were also dispersed in polymers to fabricate efficient conducting hybrid materials. The nanowire based electrodes were then integrated into various organic solar cells, with performances similar to ITO reference.Details on the synthesis of nanowires and deposition processes will be presented, including determination of deposited metal amount for high performance electrodes. Performances of OPV cells using these electrodes will also be shown and benchmarked with ITO references.

Metallic nanowire based flexible transparent electrodes for organic photovoltaic solar cells

246th National Meeting (2013)

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