Nanotechnology Today

How Close Are We To Molecular Manufacturing? (and Other Happenings in the World of Nanotechnology)

Wednesday, July 3, 2013

Efficiency Down, Energy Up

Science has spent the past several decades attempting to increase the efficiency of solar cells in order to make solar energy a viable alternative to fossil fuels.  The average solar cell has a 15-20% efficiency (i.e. converting 15-20% of solar energy into usable electricity).  Sharp Electronics has managed to develop a solar cell boasting 44.4% efficiency, however this is a concentrator system which requires lenses to concentrate sunlight onto the solar cells.  But the scientists at MIT are working on a solution that actually reduces the efficiency.  Huh?

Jeffrey Grossman, senior author of a new paper published in Nano Letters, is using nanotechnology in an effort to improve the functionality of solar cells.  Using graphene (a one-atom thick sheet of carbon atoms) and molybdenum disulfide (a one atom thick sheet of molybdenum and sulfur) together to form a 2 atom thick sheet produces a solar cell capable of converting sunlight to electricity at an efficiency of 1-2%.  While hardly efficient, because it is only 1 nanometer thick (1 billionth of a meter), they can be stacked to boost the overall efficiency of the system.  Pound for pound, this new material generates a 1,000 times more energy than conventional photovoltaics.  This can open the door for weight-sensitive applications such as aircraft or hard to access locations where transportation costs factor in.

While it is not yet manufactured in bulk, molybdenum disulfide is cheaper than silicon and opens the door to the potential for cheaper energy from the sun.