ISOS Conference - A clear success

	Box: Next year's summit, ISOS-4, will take place in Colorado where NREL is hosting the conference. Read more here. Solar Energy Materials & Solar Cells is intended as a vehicle for the dissemination of research results on materials science and technology related to photovoltaic, photo thermal and photo electrochemical solar energy conversion. Materials science is taken in the broadest possible sense and encompasses physics, chemistry, optics, materials fabrication and analysis for all types of materials. Read more here.  Round robin: In experimental methodology, a round robin test is an inter-laboratory test (measurement, analysis, or experiment) performed independently several times. There are different reasons for performing a round robin test: Determine the Reproducibility of a test method or process or to verify a new method of analysis: If a new method of analysis has been developed, a round robin test involving proven methods would verify whether the new method produces results that agree with the established method.

A direct result of the conference is going to be the publishing of a whole series of articles in the journal: Solar Energy Materials & Solar Cells. They will produce a special issue with articles from the keynote speakers and an article describing the findings from a recent Risø DTU initiated polymer solar cell round-robin that were discussed at the conference. In addition to this, there is also a blueprint for a comprehensive guideline on how to create stability measurements on polymer solar cells will be published.

The search for stability
Polymer solar cells are a relatively new technology compared to the more established silicon-based solar cell technology. Polymer solar cells have several advantages that make it interesting to develop the technology. They are potentially very cheap to manufacture with roll to roll techniques, and the active substances which convert solar energy into electricity, are nowhere near as expensive as the silicon that conventional solar cells are based on.

The Achilles heel, if you can talk about one, is that they are not as stable as the silicon-based cells. And it is precisely the lack of stability which is the conference hub. Dr. Eva Bundgaard, a Post. Doc with the Solar Energy Programme, was a part of the ISOS-3 planning group and took her share of the work load on the conference planning. She explains:

"Some 80 researchers from most of Europe, USA and Asia attended the conference which was scheduled for April but due to volcanic ash from Iceland had to be postponed until late October. There was plenty to do getting the practicalities in place. Before and after the conference itself experimental workshops were held here at Risø DTU. At the workshop researchers could test their own active ingredients for polymer solar cells in Risø's successful large-scale production equipment."

Unique insight into large-scale production
There are very particular challenges when working on a large-scale production and Risø DTU's research group is one of the few who have taken up the challenge. Challenges include how to transfer the power you can measure in the small compact cells, which other researchers typically work with, to a larger scale, since larger area generally means lower power. And then there's the whole issue of price and quantity of both the active ingredients, not to mention the production and the device.

"The 30 workshop participants came primarily from academia, and got the chance to get a unique insight into the challenges of working with roll to roll techniques. They could watch up close how much work and expertise it takes to get the production running, as there were lots of smaller challenges along the way in the workshop. And it requires that one is a bit of a problem solver when working with this new technique", Eva explains.


Photo: Picture from the workshop where they worked with roll-to-roll techniques.

All participants had only positive feedback from the workshop, and went to the task with great enthusiasm. In return they received the latest available knowledge with regards to techniques that they could take home to their own laboratories.

Sharing knowledge in a young industry
The conference itself ran over three days where the first day was spent as a traditional conference with presentations from leading research groups and a poster session where teams presented their progress. The next two days were a bit more unconventional. Here lectures were followed by discussion in 3 smaller groups.

"It was really exciting to participate in the discussions that took place at the conference. The technology is still so young that many unanswered questions still remain. This means that there is a great openness and goodwill when it comes to sharing knowledge across both academia and industry. And we are still in the process of building consensus in the field. Not just on different approaches but also on something as essential as a common measurement method. , "Says Eva Bundgaard.

In the budding polymer solar cell industry a number of so-called round-robin rounds has been launched. During a round-robin materials are send around to many different laboratories, to test and measure its properties. At the conference results from a round-robin initiated by Frederick C. Krebs, and based on polymer solar cells produced at the workshop at Risø DTU in April 2010, was discussed in one of the sessions and a new round-robin will elapse in 2011.

"Round-Robin"
In the launched round-robin the solar cells stability was measured to ascertain that solar cell stability can be verified in other laboratories, and so that you can obtain a common framework of understanding when results from different research groups can be comparable.

"The experiment, however, showed very clearly that it is unfortunately still the case that one cannot compare results from one laboratory to another. There are simply still too many uncertainties involved in measuring methods. Therefore, we also discussed how the industry could work towards getting a standard, as seen, for the silicon-based solar cells, "explains Eva. This discussion resulted in the article with the guidelines which is published in the above-mentioned special issue.

The Conference also decided to launch yet another round-robin test, number four, that focuses on measuring the efficiency of the cells.


Photo: picture from the workshop where participants could test their own active substances.