TechBlog

Bypassing decades-old conventions in making computer chips, Princeton engineers developed a novel way to replace silicon with carbon on large surfaces, clearing the way for new generations of faster, more powerful cell phones, computers and other electronics.

The electronics industry has pushed the capabilities of silicon — the material at the heart of all computer chips — to its limit, and one intriguing replacement has been carbon, said Stephen Chou, professor of electrical engineering. A material called graphene — a single layer of carbon atoms arranged in a honeycomb lattice — could allow electronics to process information and produce radio transmissions 10 times better than silicon-based devices.

Until now, however, switching from silicon to carbon has not been possible because technologists believed they needed graphene material in the same form as the silicon used to make chips: a single crystal of material 8 or 12 inches wide. The largest single-crystal graphene sheets made to date have been no wider than a couple millimeters, not big enough for a single chip. Chou and researchers in his lab realized that a big graphene wafer is not necessary, as long they could place small crystals of graphene only in the active areas of the chip. They developed a novel method to achieve this goal and demonstrated it by making high-performance working graphene transistors. 

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New York — Applied Materials, Inc. recently announced it was named Green Energy Innovator of the Year for its pioneering work on the Applied SunFab Thin Film Line, at a gala presenting the prestigious 9th Annual Platts Global Energy Awards.

“Applied Materials is focused on lowering the cost of solar photovoltaic generated energy through the application of nanomanufacturing technologies,” said Mark Pinto, Senior Vice President, Chief Technology Officer and General Manager Energy and Environmental Solutions. “The nominees in the category of Green Energy Innovator were international in breadth and included leading global green energy innovators. Amongst such competition, I am pleased to receive this acknowledgement and proud of the great work our teams around the world are doing to help make solar energy an affordable solution to the world’s power needs.”

The award highlighted the revolutionary SunFab, the world’s first and only integrated production line for manufacturing thin film silicon solar modules using 5.7 square meter (m2) glass panels. These ultra-large substrates, sized at 2.2m x 2.6m, are four times bigger than today’s typical thin film solar modules. Key to the SunFab’s success is that it can be replicated by customers around the globe to rapidly establish solar panel manufacturing capacity and achieve lower production cost per watt to drive down the cost of solar electricity.

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In the race to make solar cells cheaper and more efficient, many researchers and start-up companies are betting on new designs that exploit nanostructures — materials engineered on the scale of a billionth of a meter. Using nanotechnology, researchers can experiment with and control how a material generates, captures, transports, and stores free electrons — properties that are important for the conversion of sunlight into electricity.Two nanotech methods for engineering solar cell materials have shown particular promise. One uses thin films of metal oxide nanoparticles, such as titanium dioxide, doped with other elements, such as nitrogen. Another strategy employs quantum dots — nanosize crystals — that strongly absorb visible light. These tiny semiconductors inject electrons into a metal oxide film, or “sensitize” it, to increase solar energy conversion. Both doping and quantum dot sensitization extend the visible light absorption of the metal oxide materials.Combining these two approaches appears to yield better solar cell materials than either one alone does, according to Jin Zhang, professor of chemistry at the University of California, Santa Cruz. Zhang led a team of researchers from California, Mexico, and China that created a thin film doped with nitrogen and sensitized with quantum dots. When tested, the new nanocomposite material performed better than predicted — as if the functioning of the whole material was greater than the sum of its two individual components.

“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,” said Zhang. “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.”

The group’s findings were reported in the Journal of Physical Chemistry in a paper posted online on January 4. Lead author of the paper was Tzarara Lopez-Luke, a graduate student visiting in Zheng’s lab who is now at the Instituto de Investigaciones Metalurgicas, UMSNH, Morelia, Mexico.

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