Researchers at Stanford University have developed a new technology that promises to increase the efficiency of thin-film solar cells (TFSC). Whereas traditional methods allow light to pass straight through the outer layer of the cells to the photovoltaic material underneath, this solution utilizes Nanocrystalline silicon to trap light inside "nanoshells." The nanoshells force light to circulate inside their structure several times, allowing the photovoltaic material underneath to absorb more light. The technology works in a similar way to a whispering gallery — an architectural phenomenon that allows two people to whisper to each other while standing on opposite sides of a room.
To produce the shells, the researchers create tiny balls of silica (the base material for manufacturing glass), coat them with a layer of silicon, and then dissolve the silica using hydrofluoric acid, leaving behind light-sensitive silicon shells. The team say that the shells require just one-twentieth of the material currently needed to manufacture thin-film cells, which could allow for the use of more efficient materials in the future.
"A twentieth of the material, of course, costs one-twentieth and weighs one-twentieth what a solid layer does... This might allow us to cost effectively produce better-performing solar cells of rare or expensive materials."
Thin-film solar cells are shaping up to be an important technology for the future — recently we saw a prototype that used TFSC inside a phone display in order to improve battery life. The main problem with the technology at present is efficiency, as even the best cells have been capable of converting only 20 percent of available light, less than half of the most efficient full-sized panels. It's extremely early days for the tech at the moment and although the team says this solution will be more efficient and cost-effective, it's not providing any figures just yet.