In an effort to improve the efficiency of solar cells, researchers have shifted their focus from the active material of the cell to its coating. Using the phenomenon of Whispering Gallery Modes, which describe the way whispers under cathedral-like domes can be clearly heard far across the room, they designed a commonplace, inexpensive coating that theoretically increases the light delivered to a typical thin-film amorphous-silicon (a-Si) solar cell’s photovoltaic (PV) material by 12-15%.
The researchers attempted to demonstrate that by starting with any thin-film solar cell with smooth surfaces and fabricated on a flat substrate, they could enhance the absorption by applying a coating to the thin film cell, without roughening the flat, smooth surfaces. Their concept involves a layer of nanospheres arrayed above the PV material.
The most exciting aspects of the research are that the nanosphere array layer is calculated to produce a twelve percent to fifteen percent increase in sunlight absorption of typical anti-reflection coated a-Si thin film solar cells, the array can be made from common and cheap silicon dioxide or polystyrene, and known and existing manufacturing processes can be used to add it to typical thin-film solar cells.
The researchers expect further experimental work to clarify ways that spheres of different sizes can be used to tune both size and spacing for even more optimum efficiencies.
Light Absorption Enhancement in Thin-Film Solar Cells Using Whispering Gallery Modes in Dielectric Nanospheres
To be published in Advanced Materials in the October 2011 issue.
Gopal R. Rao, Ph.D.
Web Science Editor
Materials Research Society (MRS)