Graphene CVD sheets - updates and market status - Page 12

Researchers from Glasgow University have come up with a method to mass produce graphene in a process that is reportedly much cheaper to employ than the current one.

The team used CVD in their research, but instead of using the traditional surface, used copper foils as the surface wherein high-grade graphene is created. As these copper foils are much cheaper than the usual substrate, the cost of production decreased dramatically.

An international team of researchers from six countries have designed a highly sensitive gas sensor made from boron-doped graphene, able to detect noxious gas molecules at extremely low concentrations, parts per billion in the case of nitrogen oxides and parts per million for ammonia. These sensors can be used for labs and industries that use ammonia, a highly corrosive health hazard, or to detect nitrogen oxides, a dangerous atmospheric pollutant emitted from automobile tailpipes. In addition to detecting toxic or flammable gases, theoretical work indicates that boron-doped graphene could lead to improved lithium-ion batteries and field-effect transistors. 

The sensor reaches a 27 times greater sensitivity to nitrogen oxides and 10,000 times greater sensitivity to ammonia compared to pristine graphene. The researchers believe these results will open a path to high-performance sensors that can detect trace amounts of many other molecules.

A few days ago we reported that the Fraunhofer Institute FEP will demonstrate an OLED device with a graphene-based electrode, as part of project GLADIATOR. The researchers hope that the graphene will enable devices that are highly flexible and stable. The CVD-produced monolayer graphene was produced by Graphenea, and the project that will run until April 2017 aims to produce larger demonstrators.

We had the good chance of talking to Beatrice Beyer, the project's coordinator at the Fraunhofer Institute, and she was kind enough to answer a few questions we had regarding the project and the technology they develop.

Q: Beatrice, thanks for your time. Can you explain to us how the graphene compares to ITO as an OLED electrode?

For the time being, the optoelectronic performance of graphene as a transparent electrode is still not as good as for the mature 'industry standard' ITO, but the performance and production technologies are continuously improving and we are optimistic that soon graphene based devices will reliably compete with ITO based on performance.

A newly published patent filing from LG reveals the specifications for a next-gen microwave oven that includes a graphene door to prevent the radiation inside from leaking out, ensuring more uniform heating. While the microwave itself sounds interesting, it seems that the manufacturing process, which follows a special layering approach, is the real innovation.

The process begins when a catalyst metal with microwave shielding properties such as copper is sandwiched between two layers of graphene synthesized by CVD. Next, a number of support materials are added to the structure in order to support the subsequent etching phases, which pattern the individual layers in a way that exposes both the graphene absorbent and the catalyst metal with its shielding properties for double effect.

As part of project GLADIATOR, The Fraunhofer Institute FEP will show an innovative organic light emitting diodes (OLEDs) with a graphene-based electrode at Plastic Electronics 2015. The fabricated OLED on transparent graphene electrodes has been realized on a small area, and the target of the next one and a half years of the project is to successfully achieve large area OLEDs.

With graphene as an electrode, the researchers at the Fraunhofer FEP hope for flexible devices with higher stability. The electrode contains CVD-produced monolayer graphene of high quality, supplied by Graphenea, in order to compete with the reference material ITO (which graphene, in this case, replaces), the transparency and conductivity of graphene must be very high. Therefore, not only the process of electrode manufacturing is being optimized, but also different ways of doping graphene to improve its properties are being examined.

In a research funded by a U.S. Department of Defense-Multidisciplinary University Research Initiative grant and Wenzhou Medical University, an international team of scientists has developed what is referred to as the first one-step process for making seamless carbon-based nanomaterials that possess superior thermal, electrical and mechanical properties in 3D. The research may hold potential for increased energy storage in high efficiency batteries and supercapacitors, increasing the efficiency of energy conversion in solar cells, for lightweight thermal coatings and more. 

The group's early testing showed that a 3D fiber-like supercapacitor made with uninterrupted fibers of carbon nanotubes and graphene matched or even surpassed bettered the reported record-high capacities for such devices. When tested as a counter electrode in a dye-sensitized solar cell, the material enabled the cell to convert power with up to 6.8% efficiency and more than doubled the performance of a similar cell that used an expensive platinum wire counter electrode. 

A few weeks ago we reported on a new IDTechEx market report, in which they predict that the graphene market will reach nearly $200 million by 2026, with the estimation that the largest sectors will be composites, energy applications and graphene coatings.

We were very interested in learning more, and Dr Khasha Ghaffarzadeh, IDTechEx's head of consulting was kind enough to answer a few questions and explain the company's view on the graphene market.

Q: IDTechEx has been following graphene for a long time with dedicated events and reports. Why is this new material interesting for IDTechEx?

We have a long track record of analyzing emerging advanced materials such as quantum dots, CNTs, Ag nanostructures, silicon nanostructures, OLED materials, etc. We were however pulled into the world of graphene by our clients’ questions. Once in, we soon realized that there is a big synergy between graphene and our events. in fact, our events on supercapacitors and printed electronics were the right near-term addressable market for graphene, and that is why we managed to rapidly build up the largest business-focused event on graphene. Our events on graphene are held in the USA and Europe each year see www.IDTechEx.com/usa.

Scientists at James Cook University in Queensland, Australia, and collaborators from institutions in Australia, Singapore, Japan, and the US have developed a new technique for growing graphene from tea tree extract. Graphene is only made of carbon atoms, so theoretically can be grown from any carbon source, but scientists are still looking for a graphene precursor and growth method that is sustainable, scalable, and economically feasible, since these are all requirements for realizing widespread commercialization of graphene-based devices.

In this study, the researchers have grown graphene from the tea tree plant Melaleuca alternifolia, a plant used to make essential oils in traditional medicine. They demonstrated that it is possible to fabricate large-area, nearly defect-free graphene films from tea tree oil in as little as a few seconds to a few minutes, whereas current growth methods usually take several hours. Unlike current methods, the new method also works at relatively low temperatures, does not require catalysts, and does not rely on methane or other nonrenewable, toxic, or explosive precursors.

Researchers at the University of Wisconsin-Madison have discovered a way of growing graphene nanoribbons with desirable semiconducting properties directly on a conventional germanium semiconductor wafer. This finding may allow manufacturers to easily use graphene nanoribbons in hybrid integrated circuits, which promise to deliver a major boost to the performance of next-gen electronic devices. This technology could also have specific uses in industrial and military applications, such as sensors that detect specific chemical and biological species and photonic devices that manipulate light.

The technique for producing graphene nanoribbons is said to be scalable and compatible with the prevailing infrastructure used in semiconductor processing - nanoribbons that can be grown directly on the surface of a semiconductor like germanium are more compatible with planar processing used in the semiconductor industry, and so would pose less of a barrier to integrating these materials into electronics in the future.

Scientists from Germany, the Netherlands, Spain and Saudi Arabia, along with Graphenea, designed an improved process for achieving wafer-scale fabrication of graphene devices. The process is said to be reliable and produce graphene sheets that are smooth and uniform across the wafer, conformally covering the electrode structures. 

The process relies on a series of actions that overturns traditional fabrication norms - lithography and contact evaporation are performed prior to graphene transfer. In the research, the scientists studied the values reported in literature for contact and sheet resistance obtained with the standard graphene fabrication and transfer method. Focusing on graphene grown by CVD, they found that there is significant scatter in the reported values. The scientists then performed the standard procedure themselves, finding that the resulting graphene sheet is inhomogeneous, with defects appearing in random places.