New inorganic semiconductor layers hold promise for solar energy

A team of researchers from the University of Chicago and the U.S. Department of Energy's (DOE) Argonne National Laboratory has demonstrated a method that could produce cheaper semiconductor layers for solar cells.

The inorganic nanocrystal arrays, created by spraying a new type of colloidal "ink", have excellent electron mobility and could be a step towards addressing fundamental problems with current solar technology.

"With today's solar technology, if you want to get significant amounts of electricity, you'd have to build huge installations over many square miles," said team leader Dmitri Talapin, who holds a joint appointment with Argonne and the university.

But because current solar cells are based on silicon, which is costly and environmentally unfriendly to manufacture, they aren't cost-effective over large areas. The challenge for scientists is to find a way to manufacture large numbers of solar cells that are both efficient and cheap.

One possibility to make solar cells more economically would be to "print" them, similar to how newspapers are printed. "You'd use a kind of 'ink,' stamped on using a roll technology with a flexible substrate," Talapin said.

Solar cells have several layers of different materials stacked on top of each other. The team focused on the most important layer, which captures sunlight and converts it into electricity. This layer, made of a semiconducting material, must be able to transform light into negative and positive electrical charges but also easily release them to move further along the material to generate electrical current.