Cambridge University researchers have found a way to unleash more current from organic solar cells – a breakthrough that could not only revolutionise renewable energy but also enhance display technology used in cell phones and TVs.
A Cavendish Laboratory team in the UK has led the advance and is exploring ways to accelerate commercialisation following a joint study with the University of Washington.
The potential power of organic solar cells has long been recognised but consistency issues have dogged progress. Cavendish researchers believe they have found the solution.
They developed sensitive, laser-based techniques to track the motion and interaction of electrons in these cells. They were surprised to find 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 close the gap between organic and silicon solar cells, bringing the large-scale deployment of solar cells closer to reality.
They also believe that some of these design concepts could 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 work on solar cells at Cambridge forms part of a broader initiative to harness hi-tech knowledge in the physics sciences to tackle global challenges such as climate change and renewable energy.
Organic solar cells are a new class of solar cell that mimics the natural process of plant photosynthesis but currently lack the efficiency to compete with the more costly commercial silicon cells.
At the moment, organic solar cells can achieve as much as 12 per cent efficiency in turning light into electricity, compared with 20 to 25 per cent for silicon-based cells. The breakthrough by the Cavendish 'spin doctors' is set to literally change the balance of power.
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