Organic solar cells are a type of solar cell that produce energy by mimicking the process of plant photosynthesis. Compared to current silicon based solar cells they are thinner and more flexible. This means that the production process is likely to be faster and cheaper than before.
However, until recently they lacked the efficiency to be able to compete with their commercial counterparts. For instance, they can achieve just 12% efficiency in turning light into electricity, compared with 20-25% for silicon-based cells. This is partly due to the problem of consistency as scientists have been struggling to find out why some types of molecules outperform others.
This has changed with the new report by the University of Washington and the University of Cambridge. They discovered that the differences in the performance of molecules is due to their “spin”. “Spin” is a quantum property of particles related to their angular momentum with electrons being categorised as either “spin-up” or “spin-down”. One of the reasons why organic solar cells seemed to be inefficient is due to the process of “recombination”, where electrons lose their energy. Researchers now have found that if they arrange the “spin” in a certain way then they can block this loss of energy and increase the current flow from the cell.
The team believe that the new design concepts from this work will help to close the gap between the organic and more commercial silicon cells. In the long term this will help to deploy solar cells on a large scale. There are also benefits outside of renewable energy. The researchers also believe that some of the design concepts could also be used in OLEDs (Organic Light Emitting Diodes). This is a fast growing display technology used to make the displays on phones and TVs more efficient.
Dr Akshay Roa, who is a Cavendish Laboratory Research Fellow, has commented that “this discovery is very exciting, as we can now harness spin physics to improve solar cells, something we had previously not thought possible. We should see new materials and solar cells that make use of this very soon.”
The breakthrough is important it means that better designs can be created for these cells. Even though solar cells now provide less than 0.2% of power in the US, better designs mean that the cells become more efficient and cost effective. As a result, in theory organic solar cells may revolutionize the way that we collect renewable energy in years to come.
The study has been published in the journal Nature.
Related articles
- Regulating electron ‘spin’ may be key to making organic solar cells competitive (sciencedaily.com)
- Electron spin key to solar cell breakthrough (venitism.blogspot.com)
- Weaving power generation into the fabric of everyday life | Lou Del Bello (theguardian.com)
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