Category Physics

Molecular Nanoribbons as Electronic Highways

One-dimensional (1D) zigzag [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoribbons are produced by folding two-dimensional ultrathin PCBM nanosheets in a simple solvent process. The unique 1D PCBM nanostructures exhibit uniform width of 3.8 ± 0.3 nm, equivalent to four PCBM molecules, and lengths of 20–400 nm. These nanoribbons show well-defined crystalline structure, comprising PCBM molecules in a hexagonal arrangement without trapped solvent molecules. First-principle calculations and detailed experimental characterization provide an insight into the structure and formation mechanism of the 1D PCBM nanoribbons. Given their dimensions and physical properties, we foresee that these nanostructures should be ideal as acceptor material in organic solar cells.

One-dimensional (1D) zigzag [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoribbons are produced by folding two-dimensional ultrathin PCBM nanosheets in a simple solvent process. The unique 1D PCBM nanostructures exhibit uniform width of 3.8 ± 0.3 nm, equivalent to four PCBM molecules, and lengths of 20–400 nm. These nanoribbons show well-defined crystalline structure, comprising PCBM molecules in a hexagonal arrangement without trapped solvent molecules. First-principle calculations and detailed experimental characterization provide an insight into the structure and formation mechanism of the 1D PCBM nanoribbons. Given their dimensions and physical properties, we foresee that these nanostructures should be ideal as acceptor material in organic solar cells.

Physicists have develope...

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Light-Based Memory Chip is the 1st ever to Store Data Permanently

A schematic of the device, showing its structure and the propagation of light through it. Credit: Image courtesy of University of Oxford

A schematic of the device, showing its structure and the propagation of light through it. Credit: Image courtesy of University of Oxford

The device, which makes use of materials used in CDs and DVDs, could help dramatically improve the speed of modern computing. Today’s computers are held back by the relatively slow transmission of electronic data between the processor and the memory. ‘There’s no point using faster processors if the limiting factor is the shuttling of information to-and-from the memory — the so-called von-Neumann bottleneck,’ explains Professor Harish Bhaskaran.

Simply bridging the processor-memory gap with photons isn’t efficient, though, because of the need to convert them back into electronic signals at each end...

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Brilliant Colors from Environmentally Friendly Crystals

Quantum dots make it possible to display any color in full brilliance. Credit: © Fraunhofer IAP

Quantum dots make it possible to display any color in full brilliance. Credit: © Fraunhofer IAP

Quantum dots have made it possible to substantially increase color quality in LCD displays. However, these cadmium-based nanocrystals have proven to be harmful to the environment. Researchers are now developing a promising alternative: quantum dots based on indium phosphide.

The landscape is breathtaking. Because it is so real, you forget for a moment that the eagle circling the sky is not outside your window, but is instead on your television. Such realistic images are not only due to high resolution displays; the colors play a role as well. This is possible thanks to quantum dots (QDs), with a thickness of a few atoms...

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Coating Fragile Perovskite in Solar cells with Graphene developed for 1st time for high efficiency

The perovskite film (black, 200-300 nm) is covered by Spiro.OMeTAD, Graphene with gold contact at one edge, a glass substrate and an amorphous/crystalline silicon solar cell. Credit: F. Lang / HZB

The perovskite film (black, 200-300 nm) is covered by Spiro.OMeTAD, Graphene with gold contact at one edge, a glass substrate and an amorphous/crystalline silicon solar cell. Credit: F. Lang / HZB

Measurements show the graphene layer is an ideal front contact in several respects. Silicon absorbers primarily convert the red portion of the solar spectrum very effectively into electrical energy, whereas the blue portions are partially lost as heat. To reduce this loss, the silicon cell can be combined with an additional solar cell that primarily converts the blue portions.

Teams at HZB have already acquired extensive experience with these kinds of tandem cells. A particularly effective complement to conventional silicon is the hybrid material called perovskite. It has a band gap of 1...

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