Graphene CVD sheets - updates and market status - Page 18

Researchers from Rice University and Tsinghua University discovered (using theoretical calculations) that defects in graphene can cause it to become weak - if they occur at the grain boundaries of graphene sheets. Those grain boundaries occur because graphene grown in labs (usually using CVD) are not perfect and this creates several "islands" of graphene that merge together. The researchers say that at these points, graphene is about half as strong as perfect graphene.

The atoms on the lines that connect those islands are called grain boundaries - and the atoms at those lines usually bond in five- and seven- atom rings. These are weaker than the normal hexagon rings of graphene. The weakest points are seven-atom rings. These are found at junctions of three islands, and that's where cracks in graphene are most likely to form.

Researchers from Harvard University developed a graphene-based electrically-tunable plasmonic mid-infrared antenna array. They say this device can be useful for multi-analyte sensors, reconfigurable meta-surfaces and optoelectronics devices.

This is the first time nanoantennas can be tuned to the mid-infrared part of the electromagnetic spectrum by simply applying a voltage. This works because a graphene sheet, placed in the nanogap of a dipole antenna, acts as an electrically tunable nano-circuit element.

PlanarTech announced today that UK's 2-DTech (a subsidiary of the University of Manchester) has ordered an enhanced planarGROW-4S CVD system. The system, which was ordered in Q3 2012 and delivered in Q4 2012 will be used to produce high quality graphene for researchers at the University of Manchester.

The planarGROW-4S system has been enhanced to include a 3-zone 1,400C high-temperature furnace and an Oerlikon turbopump for ultra-high vacuum operation.

New research done by Nokia shows that mechanically flexible all-solid state batteries can be made from monolayer graphene (provided by Graphenea and grown by CVD directly onto copper foil). The total thickness of the resulting battery was about 50 micrometer. The complete structure is a cathode graphene (on copper foil), polymer electrolyte, and anode lithium foil

The researchers report that the ultrathin battery showed the highest energy density of 10 W h L^-1 and the highest power density of 300 W L^-1. It also shows excellent cyclic stability and sustains a discharge current density of 100 microA cm^-2 over 100 cycles, maintaining energy capacity over 0.02 mA h cm^-2.

The ten-year European graphene research program (called FET - Graphene Flagship) was awarded €1 billion. This project includes 74 partners, and Spain's Graphenea was happy to tell us that their the main graphene producer for this project.

Graphenea has a pilot line with a capacity of 50,000 cm²/year of CVD graphene. The company plans to extend this line to 130 milion cm²/year in the near future (that's 2600 times the current capacity!).

Researchers from Oxford University has found a new way of growing defect-free graphene using CVD. Defects weaken the material and prevent electronics from flowing freely through it, and this method could pave the way toward large-scale graphene production.

Graphene domains across grain boundaries

The researchers say that the random graphene flakes which are formed during the CVD process can be lined up by manipulating the alignment of carbon atoms on a relatively cheap copper foil. In fact the atomic structure of the copper surface acts as a 'guide' that controls the orientation of the carbon atoms growing on top of them. By combining the control of the copper foil and the pressure applied during growth makes it possible to control the thickness of these domains, the geometry of their edges and the grain boundaries where they meet.

The University of Cambridge announce plans to establish a new center for graphene research. The Cambridge Graphene Centre (CGC) will start operation on February 1st 2013 and the university will open a dedicated facility with state-of-the-art equipment towards the end of 2013.

The UK government gave a grant of over £12 million to support the new center's activities. The CGC will use the money to buy equipment and support projects that aim to develop new mass-production high-quality graphene production processes and some potential applications. The CGC's director will be Professor Andrea Ferrari.

Researchers from the Beckman Institute have researchers the electronics behavior of graphene with grain boundaries. They explain that when graphene is grown, lattices of the carbon grains are formed randomly, linked together at different angles of orientation in a hexagonal network. But sometimes when the process is not perfect, defects called grain boundaries (GBs) form. These boundaries scatter the flow of electrons in graphene, which harms the material's electronic performance.

The researchers grew polycrystalline graphene on a silicon wafer using CVD, and then examined the atomic-scale grain boundaries using scanning tunneling microscopy and spectroscopy. The electron scattering at the boundaries significantly limits the electronic performance compared to grain boundary free graphene.  In fact they say that when the electrons' itinerary takes them to a grain boundary, it is like hitting a hill - the electrons bounce off, interfere with themselves and create a wave pattern. The hill slows the electrons down - which means that the grain boundary is a resistor in series with a conductor.

Researchers from MIT developed a new solar (photovoltaic) cell that is made from several graphene sheets coated with nanowires. They say that this flexible and transparent cell could be made on the cheap.

The new solar panels use graphene as a replacement for ITO. The new electrode material is cheaper and provides several advantages over ITO: flexibility, low weight, mechanical strength and chemical robustness. The idea is to use a series of polymer coatings to modify the graphene properties, allowing them to bond a layer of zinc oxide nanowires to it, and then an overlay of a material that responds to light waves—either lead-sulfide quantum dots or a type of polymer called P3HT. Despite these modifications, graphene's innate properties remain intact.

Researchers from the University of Texas at Austin have developed flexible graphene field-effect transistors (G-FET) that features record current densities and the highest power and conversion gain ever. The team says that the transistors show near symmetric electron and hole transport and are the most mechanically robust flexible graphene devices fabricated to date. They are also resistant to water.

The G-FETs were made directly atop patterned dielectrics on plastic sheets using conventional microelectronic lithography. In those devices, multi-finger metal gate electrodes are embedded in the plastic sheet. The graphene was grown using CVD.