Precise Pressure to Improve Solar CellsCategory: Science & Technology
Posted: December 3, 2012 09:00AM
One of the obstacles for solar power is that materials often only respond to certain frequencies of light, and not more of the wide spectrum shining on them. This selectivity is related to the band gap, the property which makes a semiconductor a semiconductor. Now researchers at MIT have found a way to manipulate the band gap in order to broaden the spectrum a semiconductor can absorb.
The band gap is the gap between the conducting and non-conducting electron energy levels for an atom. If an electron does not have the energy to cross the gap, it cannot move, and thus cannot be harnessed as an electric current. What the researchers have done though is found a way to induce changes in molybdenum disulfide's (MoS2) band gap by applying force to it. This material can be made into a sheet just one molecule thick and by pressing into it to create a funnel shape, the atomic structure changes enough to tune the band gap. This tuning should make it responsive to a wider range of frequencies than it is currently.
Thus far this research has only been theoretical, but the next step will be to experimentally test it. Earlier this month we saw how again strain on a material can affect its electrical properties, but then it was making graphene a semiconductor. Together these two results definitely show that the field of strain engineering is deserving of further exploration.