Australian researchers set new record for solar cell efficiency
28 Aug 2009
A team of Australian and US researchers has set a new solar cell efficiency record when their multi-cell array achieved an efficiency of 43 per cent beating the previous record by 0.3 per cent.
Professor Martin Green of the University of New South Wales, leading the record breaking effort, said that only a fraction of the energy from the sunlight that falls on the cell is converted to electricity.
He said that sunlight is made up of small particles of light with different energy. To create electricity each photon of light must have enough energy to free an electron inside the solar cell, however if the energy of the photon is low, no electrical current is created as the photon just bounces off the cell, he added.
He added that a standard cell can respond to photons only above an energy threshold.
Silicon has a low energy threshold which allows most wavelengths of energy to free an electron, but at the same time silicon cells are not efficient in converting short wavelengths such as blue light, he said.
However, cells made of material with lower threshold are not as efficient converters are cells that are matched to that colour, according to Green.
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