Argonne National Laboratory Center for Nanoscale Materials U.S. Department of Energy

New inorganic semiconductor layers hold promise for solar energy

Inorganic surface ligands

Inorganic surface ligands enable facile electron transport between quantum dots and opened novel opportunities for using nanostructures in solar cells.

Inorganic dot array

Arrays of quantum dots allow fabrication of solar cells by printing and other inexpensive techniques.

A team of users from the University of Chicago, working with the NanoBio Interfaces Group, 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 toward addressing fundamental problems with current solar technology.

Because current solar cells are based on silicon, which is costly and environmentally unfriendly to manufacture, they are not cost-effective over large areas. The challenge 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. 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 transform light into negative and positive electrical charges and easily release them to generate electrical current.

Many methods to grow the semiconductors need high temperatures, but a cheaper approach would be to make them in solution. The team developed a soluble precursor using quantum dots. Small grains of semiconductors suspended in a liquid were "glued" together with molecular metal chalcogenide complexes. The process heats the material to about 200°C, much lower than the temperatures required for manufacturing silicon solar cells. The result is a layer of material with good semiconducting properties.

J.S Lee et al., "Band-like transport, high electron mobility and high photoconductivity in all-inorganic nanocrystal arrays," Nature Nanotech., 6, 348-352 (2011) (online)

In the News

June 2011

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