Zinc oxide gives green shine to new photo...( Photodetectors -- devices found in c...)

Photodetectors -- devices found in cell phones, digital cameras and other consumer gadgets that utilize photoconducting materials -- are a green technology in performance (converting light into electricity), but the manufacture of very powerful photodetectors needs to be improved before they can qualify for solid green status.

This is especially true if photoconducting materials are to be widely used for producing solar energy.

Northwestern University researchers have designed a high-performing photoconducting material that uses zinc oxide -- an environmentally friendly inorganic compound found in baby powder and suntan lotion -- instead of lead sulfide. (Currently, the best performing photoconductor is based on lead sulfide nanoparticles.)

The new material converts light into electricity but, unlike conventional materials, also features a novel combination of attractive attributes: environmentally benign chemistry, low-cost production, a high level of detectivity, mechanical flexibility and wavelength tunability (ability to design the material to absorb the most important part of the solar spectrum).

This impressive package of features holds promise for the material's use in large-area photovoltaic solar cells as well as flexible electronics -- even in clothing and newspapers. Conventional photoconducting materials are expensive to manufacture, making them unsuitable for widespread solar energy use, and they are rigid, making them unsuitable for flexible electronics.

Features of the new hybrid material and its synthesis are detailed in a study published by the journal Nature Materials.

"One property of our hybrid material that is especially important for solar-energy devices is its high level of detectivity -- less light is needed to get a good strong and clear signal," said lead researcher Samuel I. Stupp, Board of Trustees Professor of Materials Science and Engineering, Chemistry and Medicine at No
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