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Organic solar cells set to revolutionize renewable energy

Last Updated: Thursday, August 8, 2013 - 14:39

Washington: Researchers have discovered that manipulating the `spin` of electrons in organic solar cells, a new class of solar cell mimicking the natural process of plant photosynthesis, dramatically improves their performance.

The sells currently lack the efficiency to compete with the more costly commercial silicon cells and can just achieve as much as 12 percent efficiency in turning light into electricity, compared with 20 to 25 percent for silicon-based cells.

However, researchers from the Universities of Cambridge and Washington discovered that manipulating the `spin` of electrons has provided a vital breakthrough in the pursuit of cheap, high performing solar power technologies.

Organic solar cells replicate photosynthesis using large, carbon-based molecules to harvest sunlight instead of the inorganic semiconductors used in commercial, silicon-based solar cells.

These organic cells can be very thin, light and highly flexible, as well as printed from inks similar to newspapers - allowing for much faster and cheaper production processes than current solar cells.

Researchers from Cambridge`s Cavendish Laboratory developed sensitive laser-based techniques to track the motion and interaction of electrons in these cells. To their surprise, the team found that the performance differences between materials could be attributed to the quantum property of `spin`.

`Spin` is a property of particles related to their angular momentum, with electrons coming in two flavours, `spin-up` or `spin-down`.

Electrons in solar cells can be lost through a process called `recombination`, where electrons lose their energy - or "excitation" state - and fall back into an empty state known as the "hole".

Researchers found that by arranging the electrons `spin` in a specific way, they can block the energy collapse from `recombination` and increase current from the cell.

"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" said Dr. Akshay Rao, a Research Fellow at the Cavendish Laboratory and Corpus Christi College, Cambridge, who lead the study with colleagues Philip Chow and Dr. Simon Gelinas.

The Cambridge team believe that design concepts coming out of this work could help to close the gap between organic and silicon solar cells, bringing the large-scale deployment of solar cells closer to reality.

In addition, some of these design concepts could also be applied to Organic Light Emitting diodes, a new and rapidly growing display technology, allowing for more efficient displays in cell phones and TVs.

The study has been published in the journal Nature.


First Published: Thursday, August 8, 2013 - 14:39
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