Could lead to further solar power cost reductionsThe latest breakthrough by the University of New South Wales in Australia falls in the latter category. They've found a way to make very high efficiency solar cells out of low-grade silicon with more defects and contaminants, but also a lower price.
Standard commercial silicon cells currently have a maximum efficiency of around 19%. The new technique, patented by UNSW researchers earlier this year, is expected to produce efficiencies between 21% and 23%, says Scientia Professor Stuart Wenham from the School of Photovoltaics and Renewable Energy Engineering at UNSW.
The trick is a novel way to control hydrogen atoms in the silicon:
It’s been known for several decades that hydrogen atoms can be introduced into the atomic structure of silicon to help correct these defects, but until now, researchers have had limited success in controlling the hydrogen to maximise its benefits or even understanding why this happens.
“Our research team at UNSW has worked out how to control the charge state of hydrogen atoms in silicon – something that other people haven’t previously been able to do,” says Wenham.
Hydrogen atoms can exist in three ‘charge’ states – positive, neutral and negative. The charge state determines how well the hydrogen can move around the silicon and its reactivity, which is important to help correct the defects.
“We have seen a 10,000 times improvement in the mobility of the hydrogen and we can control the hydrogen so it chemically bonds to things like defects and contaminants, making these inactive,” says Wenham. (source)
This technology is still in the lab and probably won't be seen in commercial products for a number of years, but the UNSW team is already working with industry partners and equipment manufacturers to bring it market. Hopefully everything works out and this becomes one of many advances to bring the cost of solar power lower and lower...