Posted: November 10, 2009

Upconversion significantly boosts solar cell efficiency

(Nanowerk News) University of Sydney researchers Dr Tim Schmidt and Professor Max Crossley have come up with an ingenious low-cost device to harvest low energy photons, with the potential of significantly boosting the efficiency of conventional solar cells using a process called upconversion.
Schmidt and Crossley, from the University's School of Chemistry, have achieved a massive jump in upconversion efficiency, enabling an efficiency increase in single threshold solar cells of about one-third. This is done by harvesting the part of the solar spectrum currently unused by solar cells.
The team are synthesising unique sensitiser and emitter molecules to bring about tailor-made devices to boost solar energy conversion efficiencies in two types of solar cell: amorphous silicon, and crystalline silicon.
The findings, which are published in the most recent issue of the journal Physical Chemistry Chemical Physics, pave the way to boosting the efficiency limit to over 50 per cent under the standard solar spectrum and up to 63 per cent under 100 fold solar concentration.
"All but the most expensive solar cells utilise a material with a Single energy threshold in the material which produces voltage by promoting electrons above this threshold upon absorption of light," said Dr Schmidt. "As a consequence, particles of light (photons) with energy less than this threshold cannot be harvested by the cell. Additionally, energy in excess of this threshold is lost to heat."
"By performing upconversion cheaply, we will lift the ceiling afflicting traditional solar calls and bring a revolution in solar cell efficiencies."
"Australia is the world leader in both of these technologies, and by applying our technology, Australia can lead the world still further," said Dr Schmidt.
Dr Schmidt was an award winner in the recently announced 2009 NSW/ACT Young Tall Poppy Awards.
Source: University of Sydney