Combo of two nanotech approaches may provide more efficient solar cells

January 9th, 2008 - 2:32 pm ICT by admin  

Washington, January 9 (ANI): Combination of two nanotechnology procedures one involving thin films of metal oxide nanoparticles doped with other elements, and the other employing quantum dots or nanosize crystals that strongly absorb visible light may significantly enhance solar cells efficiency in converting sunlight into electricity, suggests an international team of researchers.

Both doping and quantum dot sensitisation extend the visible light absorption of the metal oxide materials.

Lead researcher Jin Zhang, professor of chemistry at the University of California, Santa Cruz, says that the combination of the two approaches produces better solar cell materials than either one alone does.

His team which includes researchers from California, Mexico, and China created a thin film doped with nitrogen and sensitised with quantum dots. The new nanocomposite materials functioning was greater than the sum of its two individual components, they found.

“We have discovered a new strategy that could be very useful for enhancing the photo response and conversion efficiency of solar cells based on nanomaterials,” Zhang said.

“We initially thought that the best we might do is get results as good as the sum of the two, and maybe if we didn’t make this right, we’d get something worse. But surprisingly, these materials were much better,” he added.

Zhang believes that the nanocomposite material may provide not only solar cells with enhanced efficiency, but also a state-of-the-art photoelectrochemical cell that will use energy generated from sunlight to split water and produce hydrogen fuel.

He also feels that their nanocomposite material may potentially be useful in devices for converting carbon dioxide into hydrocarbon fuels, such as methane.

“I’m very excited because this work is preliminary and there’s a lot of optimizing we can do now. We have three materials–or three parameters–that we can play with to make the energy levels just right,” Zhang said.

He revealed that his team has been trying to manipulate materials so that when sunlight strikes them, the free electrons generated could easily move from one energy level to another, or jump across the different materials, and be efficiently converted to electricity.

“What we’re doing is essentially ‘band-gap engineering.’ We’re manipulating the energy levels of the nanocomposite material so the electrons can work more efficiently for electricity generation. If our model is correct, we’re making a good case for this kind of strategy,” Zhang said.

The research teams work has been reported in the Journal of Physical Chemistry. (ANI)

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