Revolutionary solar cells double as lasers
Date: March 28, 2014
Source: University of Cambridge
Latest research finds that the trailblazing 'perovskite' material used in solar cells can double up as a laser, strongly suggesting the astonishing efficiency levels already achieved in these cells is only part of the journey.
Commercial silicon-based solar cells -- such as those seen on the roofs of houses across the country -- operate at about 20% efficiency for converting the Sun's rays into electrical energy. It's taken over 20 years to achieve that rate of efficiency.
A relatively new type of solar cell based on a perovskite material -- named for scientist Lev Perovski, who first discovered materials with this structure in the Ural Mountains in the 19th century -- was recently pioneered by an Oxford research team led by Professor Henry Snaith.
Perovskite solar cells, the source of huge excitement in the research community, already lie just a fraction behind commercial silicon, having reached a remarkable 17% efficiency after a mere two years of research -- transforming prospects for cheap large-area solar energy generation.
Now, researchers from Professor Sir Richard Friend's group at Cambridge's Cavendish Laboratory -- working with Snaith's Oxford group -- have demonstrated that perovskite cells excel not just at absorbing light but also at emitting it. The new findings, recently published online in the Journal of Physical Chemistry Letters, show that these 'wonder cells' can also produce cheap lasers.
By sandwiching a thin layer of the lead halide perovskite between two mirrors, the team produced an optically driven laser which proves these cells "show very efficient luminescence" -- with up to 70% of absorbed light re-emitted.
The researchers point to the fundamental relationship, first established by Shockley and Queisser in 1961, between the generation of electrical charges following light absorption and the process of 'recombination' of these charges to emit light.
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