MATERIALS | PHOTOVOLTAICS
Solar cells work because a photon of light excites
an electron – leaving behind a ‘hole’. These electrons and holes can be harvested as electricity if they can be kept apart. In organic solar cells, the electron and hole are more likely to recombine than in a silicon- based solar cell – hence their lower efficiency. Researchers use two components to prevent this
recombination: a donor material, which contributes electrons; and an acceptor material, which takes up electrons to generate and transport charges. Using a combination of spectroscopy and computer modelling, the researchers tracked the mechanisms within organic solar cells, and identi- fied a key loss mechanism. They found that, by engineering strong molecu-
Above: A
self-assembly technique to create a thin surface layer has been applied to OPVs
“Organic solar cells can do lots of things that
inorganic solar cells can’t, but their commercial development has plateaued in recent years – in part due to their inferior efficiency,” said Alexander Gillett, of the Cavendish Laboratory at Cambridge University.
While a typical silicon-based solar cell has an
efficiency of 20-25%, organic solar cells reach efficiencies of less than 19% under laboratory conditions – and real-world efficiencies of 10-12%.
lar interactions between the donor and acceptor materials, it was possible to keep the electron and hole further apart – preventing them from recom- bining. The researchers say their method provides a
clear strategy for achieving organic solar cells with efficiencies of 20% or more. The next hurdle is to improve the lifetime of
organic solar cells – which the team is currently working to solve.
Improve plastic sheet and rigid food packaging
■ Anti-block agents ■ Anti-static agents ■ Anti-fog agents
IMAGE: KAUNAS UNIVERSITY OF TECHNOLOGY
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