by Colin Jeffrey @ gizmag.com:
Researchers from the University of Manchester and University of Sheffield have developed a new prototype semi-transparent, graphene-based LED device that could form the basis of flexible screens for use in the next-generation of mobile phones, tablets and televisions. The incredibly thin display was created using sandwiched “heterostructures”, is only 10-40 atoms thick and emits a sheet of light across its entire surface.
Flexible graphene-based LED clears the way for flexible displays - [Link]
IBM has not only perfected a method of growing wafer scale graphene as a potential material for the post-silicon era, but has found a way to use it today to dramatically cut the cost of GaN LEDs.
IBM Grows Wafer Scale Graphene – [Link]
The image may be a bit grainy and (at the moment) just monochrome but that is only to be expected for what is the world’s first flexible display to incorporate graphene in its pixel electronics. The new display technology is a result of collaboration between the Cambridge Graphene Centre and Plastic Logic. Plastic Logic has already developed flexible display electronics but this new prototype is an active matrix electrophoretic display, similar to the screens used in today’s e-readers, made of flexible plastic instead of glass. In contrast to conventional displays, the pixel electronics, or backplane, of this display includes a solution-processed graphene electrode, replacing the sputtered metal electrode layer within Plastic Logic’s conventional devices, bringing product and process benefits.
First Graphene-based Flexible Display - [Link]
The world’s thinnest LED at only 3 atoms thick:
Researchers at the University of Washington (UW) have demonstrated electroluminescence in a flexible, mechanically strong construct of the semiconductor tungsten selenide only three atoms thick.
The researchers harvested single sheets of tungsten selenide (WSe2) using adhesive tape, a technique invented for the production of graphene. They used a support and dielectric layer of boron nitride on a base of silicon dioxide on silicon, to come up with the thinnest possible LED.
The LEDs now used in most consumer electronics are rigid and are hundreds to thousands of times as thick as the material being developed at UW — which the team characterizes as 1/10,000th the thickness of a human hair.
Existing inorganic LEDs are not appropriate for use in bendable, foldable applications such as electronic devices and displays integrated into clothing. Organic light-emitting diodes are the usual candidates for such applications, but the techniques being pioneered at UW can produce devices that are not only much thinner — and stackable — but also far more versatile.
UW Researchers Create World’s Thinnest LED At Only 3 Atoms Thick - [Link]
In a paper published in Nature Communications researchers at IBM describe how they have built a silicon-based receiver chip incorporating GFETs or Graphene Field Effect Transistors (the purple structure in the photo) into the circuit. The multi-stage receiver integrated circuit consists of 3 graphene transistors, 4 inductors, 2 capacitors, and 2 resistors.
“This is the first time that someone has shown graphene devices and circuits to perform modern wireless communication functions comparable to silicon technology,”
said Supratik Guha, Director of Physical Sciences at IBM Research. In a test the team successfully used the graphene-based receiver to process a digital transmission on 4.3GHz. The binary sequence received was 01001001 01000010 01001101, which represents ASCII coding of the letters IBM.
IBM Chip uses Graphene FETs - [Link]
Researchers experimenting with the properties of Graphene have discovered that when the single-atom-thick sheet is exposed to extreme low temperatures and high magnetic field it has the ability to filter electrons according to their spin direction.
At room temperature and with no magnetic field the flake of graphene functions as a normal conductor with electrons flowing throughout the sheet. With the application of a magnetic field perpendicular to the sheet the electrons migrate out to the sheet edges while the rest of the sheet has the properties of an insulator. Current flow around the edges is either clockwise or anticlockwise depending on the orientation of the field (known as the quantum Hall effect).
When the MIT researchers switched a second magnetic field in the same plane as the Graphene sheet they found that electrons move around the edge in either clockwise or counterclockwise direction depending on the electron’s direction of spin. [via]
Graphene could be good for Quantum Computing - [Link]
A team of Columbia Engineering researchers, led by Mechanical Engineering Professor James Hone and Electrical Engineering Professor Kenneth Shepard, exploring the properties of graphene have demonstrated a new electro-mechanical resonant component.
The resonator’s structure consists of a 2-4 micrometer long strip of graphene suspended over a metal gate electrode. The strip of graphene has a natural resonance governed by its physical dimension and is used in the demonstration as the frequency determining element in an RF feedback oscillator circuit. Applying a voltage to the gate electrode stresses and deflects the graphene strip changing its resonant frequency. The team applied baseband audio and tones to the gate electrode to produce a 100 MHz FM signal.[via]
Tiny FM Transmitter uses Voltage Controlled Graphene Resonator - [Link]
Graphene is by definition flat and planar, but researchers at Michigan Tech have discovered a manner of fabricating 3-D graphene–a honeycomb structure that can replace the expensive precious metals in solar cells and potentially other energy applications such as batteries and even superconductors. [via]
3D Graphene for Cheaper Solar Cells - [Link]
A team of researchers at Brown University (USA) has concluded that graphene, a material touted to replace silicon in future semiconductor devices, disrupts functions of living cells. If the results of the study are confirmed by others, graphene could end up in the same hazardous material category as carbon nanotubes.
Graphene has many unique properties, but from a toxicology perspective the most important is that it is often made as a dry powder with the potential for inhalation exposure. Graphene fragments that make up the powder have sharp, pointy edges that can penetrate cell walls and allow the rest of the fragment to be drawn into the cell.
The researchers started with toxicity studies of graphene, which showed that it did in fact disrupt cell functions. To discover why, atomically detailed computer simulations of the graphene material interacting with a living cell were created. The simulations indicated the same results as the toxicity experiments. After the simulations follow-up studies were performed on human lung, skin, and immune cells in Petri dishes, and they confirmed that graphene fragments as large as 10 microns can pierce and be swallowed up by living cells. [via]
Graphene a Possible Health Hazard? - [Link]
According to researchers at the Swedish Royal Institute of Technology (KTH) in Stockholm, graphene can increase the sensitivity of micro-electromechanical system (MEMS) sensors by up to 100 times due to exteme thinness of graphene films compared to other piezoresistive materials.
Piezoresistive pressure sensors typically integrate silicon piezoresistors into sensor membranes so that strain can be read in terms of resistance. The MEMS version suspends the membrane over a cavity by etching out the underying silicon dioxide. In the KTH version, an extremely thin layer of graphene is suspended over a cavity etched into a silicon dioxide layer on a silicon substrate. The extreme thinness of the graphene membrane – less than a nanometer with a monolayer membrane – increases the sensitivity of the electromechanical effect. [via]
Graphene Beats Silicon in Strain Gauges - [Link]