mdl4:
Image of surface acoustic waves on a crystal of tellurium oxide with (001) surface orientation, coated with a thin gold film of thickness 40 nm
Source: zhk
(image via www.amazingrust.com)
Organic Light Emitting Diodes have seemed sure to be the next big thing in large and small area displays. The ease of roll to roll processing combined with the vibrant colors that OLEDs offer had nearly every researcher in the industry behind them - that is until researchers from MIT (www.mit.edu) offered an intriguing and possibly far superior alternative: quantum dot displays.
Quantum Dots are small little clusters of semiconducting atoms. When electrons are stimulated in a quantum dot, they jump from a bond site on one of the semiconductor atoms to an unbonded, “free” state. When they fall back into a bonded state, they emit light with an energy equal to the distance between the bonded and unbonded state.
The clusters that form quantum dots are so small that the electrons that sit within the cluster are confined quantum mechanically. Left on their own, free electrons would spread out into a volume much larger than what’s offered by a quantum dot. Because they are confined by the edges of the dot, however, they exist at a state of higher energy. Researchers can tune the energy jump between the unbonded state and bonded state by changing the size of the quantum dot and the corresponding space that the free electron is squashed into.
By doing this, they also control the wavelength of the light which is hitting our eyes. As shown in the picture, controlling the quantum dot size so that it yields the red, green and blue light required for a display is quite possible.
Quantum dot displays bypass some of the current existing issues for OLEDs, including current issues surrounding roll to roll processing, and issues with solvent processing. The real advantage that quantum dot displays pose, however, is they are insensitive to contamination from water in the atmosphere, so they don’t have to be processed in a glove box.
Source: amazingrust.com
(image via www.technologyreview.com)
The Nobel Prize in Physics was awarded this year to researchers from the University of Manchester (www.manchester.edu). It was awarded for the discovery of graphene, a special nanostructured form of elemental carbon which appears as a single, atomically flat, hexagonal array of atoms.
There are a lot of reasons that graphene is a discovery which is monumental enough to win a Nobel Prize: its high surface area to volume ratio being one and another being that it can be used to quantum confine the electrons that flow through it to only two dimensions. The result of quantum confinement is that electrons can flow really, really fast even though graphene also possesses characteristics common to semiconductor, where the electrons flow far slower.
Because graphene operates at blistering speeds, it’s currently being considered in satellite communications, where the circuits that transmit signals to and from the satellite must operate at frequencies nearing 1 THz (imagine if you had a computer chip that ran at 1000 GHz instead of around 5GHz like they do now - pretty fast, huh?). Graphene transistors are also ambipolar, meaning that they can conduct both positive AND negative charge equally well: a feat which semiconductors physically aren’t capable of achieving.
Researchers at University of California, Riverside (www.ucr.edu) want to use this ambipolarity to leverage Graphene in the growing communications industry by creating circuits that have higher bandwidths and, as a result, can listen to more stuff at once.
(Graphene is a direct competitor to the semiconductors i work with. With that said, I’m excited to see if they can outdo us - if for no other reason than to know where to apply for a job once I’m out of school!)
Source: technologyreview.com
(image via www.sciencedaily.com)
The secrets of “Mayan Blue”, a pigment used by the mysterious Mesoamerican culture famed for its fade-proof qualities, have finally been revealed. French physicists used X-Rays from a synchotron source scattered off of the surface of Mayan pottery to determine the structure of the strange material, which is formed by burning a mixture of indigo and clay to form a ceramic composite. High temperature migration drives the organic pigment deep into the porous structure of the ceramic as part of a sintering process, protecting the Mayan Blue from the same oxidizing and corrosive environment that tears most organic pigments apart over time.
Source: sciencedaily.com
(image via www.optics.rochester.edu)
Researchers at Tufts University have found a way to create synthetic spider silk using genetically modified E. Coli bacteria, marking a huge step forward in the search for an industrially viable form of the material. The search for synthetic dragline silk, a material long considered the holy grail of textiles because it is stronger than steel and incredibly lightweight, has stymied academic and industrial researchers alike for decades. The trouble was that the genetic code associated with the production of dragline silk protein was never fully sequenced and attempts at using this poorly sequenced genome for production resulted in correspondingly weak silk. The full genetic sequence for dragline silk was discovered last year and researchers at Tufts were scrambling since then to add this genetic sequence to E. Coli DNA. The next step towards the large-scale production of spider silk is finding an alternative to the high-temperature and caustic spinning processes required to form the tough material into a fiber.
Source: optics.rochester.edu
