Cheaper solar semiconductor layers from quantum dots, colloidal “ink”

University of Chicago researchers worked with the Argonne National Laboratory on a spray-on collodial “ink” that creates inorganic nano-crystal arrays. The solution-based manufacturing method could lead to cheaper semiconductor layers in solar cells, with “an order of magnitude” better electron mobility than previous attempts.

June 2, 2011 — University of Chicago researchers worked with the US Department of Energy’s (DOE) Argonne National Laboratory on a spray-on collodial “ink” that creates inorganic nano-crystal arrays with excellent electron mobility.

The inorganic layer could make large-area solar installations cheaper than today’s silicon-based cells, said team leader Dmitri Talapin, a joint researcher with U Chicago and Argonne. It could also be more environmentally friendly than Si.

The team developed a quantum-dot-based (QD-based) soluble precursor to manufacture solar cells using a solution-based process. Small semiconductor grains, suspended in a liquid, were”glued” together with new molecules called “molecular metal chalcogenide complexes.” The 200°C processing temperature was much lower than that used in c-Si photovoltaics manufacturing, and it resulted in a good semiconducting layer that could convert solar energy to electrical charges.

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Figure. QD arrays allow solar cell fab by printing and other inexpensive techniques.

This precursor layer enables printed solar cells manufactured with inks stamped or rolled onto the substrate, noted Talapin. The solution-based method results in electron mobility “an order of magnitude higher” than previous attempts, said Talapin, who believes the nanoparticle layer could lead to “competitive” solar cells.

Intense X-rays from the DOE Office of Science’s Advanced Photon Source at Argonne allowed researchers to watch the semiconductor film’s creation.

The study made use of University of Chicago students and postdocs who were engaged in the theoretical chemistry, and Argonne’s sophisticated instrumentation and infrastructure.

Results were published in Nature Nanotechnology, “Band-like transport, high electron mobility and high photoconductivity in all-inorganic nanocrystal arrays.” Access the article here:

The research was supported by the Office of Naval Research and a National Science Foundation CAREER award. Work at the Center for Nanoscale Materials and the Advanced Photon Source was supported by the DOE’s Office of Science.

The Center for Nanoscale Materials at Argonne National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), supported by the DOE Office of Science. For more information about the DOE NSRCs, please visit

Courtesy of Louise Lerner, Argonne.

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