By EurekAlert! – March 18, 2015 (ECNmag.com/news)
A flexible organic solar cell from TREASORES project undergoing mechanical testing: the cell is repeatedly flexed to a 25 mm radius whilst monitoring its performance. Such cells have shown lifetimes in excess of 4,000 hours. Credit (Image: National Physical Laboratory (NPL), England)
In order to make solar energy widely affordable scientists and engineers all over the world are looking for low-cost production technologies. Flexible organic solar cells have a huge potential in this regard because they require only a minimum amount of (rather cheap) materials and can be manufactured in large quantities by roll-to-roll (R2R) processing. This requires, however, that the transparent electrodes, the barrier layers and even the entire devices be flexible. The EU-funded project “TREASORES” (Transparent Electrodes for Large Area Large Scale Production of Organic Optoelectronic Devices), which started in November 2012 with an overall budget of more than 14 Mio Euro and is led by Empa researcher Frank Nüesch, aims at developing and demonstrating technologies to facilitate R2R production of organic optoelectronic devices such as solar cells and LED lighting panels.
Transparent electrodes with superior performance
The TREASORES project recently completed its mid-term review and has already achieved some major milestones. The international team that comprises researchers from 19 labs and companies from five European countries has, for instance, developed an ultra-thin transparent silver electrode that is cheaper than, and outperforms, currently used indium tin oxide (ITO) electrodes. The researchers could also demonstrate a record efficiency of 7 % for a perovskite-based solar cell using such novel transparent electrodes. What’s more, their first fully R2R-produced solar cells already achieved commercially acceptable lifetimes when tested «in the field». The next step, says Nüesch, is to scale up and improve the most promising technologies identified so far, say, to produce barrier materials and transparent electrodes in larger quantities, i.e. in rolls of more than 100 meters in length.