Electronics - Page 27

German scientists at the University of Siegen, along with scientists from the KTH-Royal Institute of Technology in Kista, Sweden, claim that laser annealing can improve the quality of printed graphene (and other 2D materials) inks. This can be beneficial for various applications like flexible electronics devices, including batteries and supercapacitors, transistors, solar cells and displays.

The researchers succeeded in producing uniform, transparent and conductive graphene thin films by simply drop-casting dispersions of the carbon sheet onto a glass surface and combining this drop-casting step with laser annealing. The annealing process involves scanning a laser beam across the surface of the films, which distinctly improves their transparency and how well they conduct electricity.

Scientists from Ulsan National Institute of Science and Technology (UNIST) and Pohang University of Science and Technology in South Korea synthesised nitrogenated 2D crystals using a simple chemical reaction in liquid phase.

Introducing foreign elements (there are not carbon) into graphene's carbon lattice structure is a known way of developing other 2D crystals. Nitrogen has a suitable atomic size and structure to fit into a strong network of carbon atoms, by creating bonds in which electrons are shared by the whole network.

A team of researchers from the University of Pennsylvania, University of California and University of Illinois at Urbana-Champaign has demonstrated a way to change the amount of electrons that reside in a given region within a piece of graphene and have a proof-of-principle in making the fundamental building blocks of semiconductor devices using the 2D material. Their method enables this value to be tuned through the application of an electric field, which means that graphene circuits made in this way could theoretically be manipulated without physically altering the device.

Chemically doping graphene to achieve p- and n-type version of the material (similar to traditional circuits) is possible, but it comes at the price of sacrificing some of its unique electrical properties. A similar effect is possible by applying local voltage changes to the material, but manufacturing and placing the necessary electrodes is complicated. The team of researchers claims it has now come up with a non-destructive, reversible way of doping, that doesn’t involve any physical changes to the graphene.

EPFL researchers investigated heat dissipation in graphene and other two-dimensional materials, and have shown that heat can propagate as a wave over very long distances. This discovery can provide a valuable tool for for cooling down circuits at the nanoscale, and contribute to the efforts to replace silicon in next-gen electronics.

2D sheets behave in unexpected ways compared to 3D ones, and understanding the propagation of heat in them is a challenge. The EPFL researchers demonstrated that heat can propagate without significant losses in 2D even at room temperature, thanks to the phenomenon of wave-like diffusion, called "second sound". In that case, all phonons (vibrations of atomes) move together in unison over very long distances. This could be of great value for future electronic components that use 2D materials. 

Scientists at the University of Basel demonstrated for the first time that electrons in graphene can be moved along a predefined path. This movement occurs without loss and could provide a basis for electronics applications.

Electrons are known to move through graphene practically undisturbed similar to rays of light. Attempts have been made to find a way to guide them, which the Basel team has now accomplished. The developed mechanism is based on a graphene property - combining an electrical field and a magnetic field makes the electrons move along a snake state. The line bends to the right, then to the left due to the sequence of positive and negative mass a phenomenon unique to graphene that could be used as a novel switch that can be incorporated into a wide variety of devices and operated simply by altering the magnetic field or the electrical field.

Researchers from the University of Minnesota used an ultrathin black phosphorus film of only 20 layers of atoms to demonstrate high-speed data communication on nanoscale optical circuits. They report that the devices show improved efficiency compared to graphene-based ones.

The University of Minnesota team created intricate optical circuits in silicon and then laid thin flakes of black phosphorus over these structures using facilities at the University's Minnesota Nano Center. The team showed that the performance of the black phosphorus photodetectors even rivals that of comparable devices made of germanium, considered the gold standard in on-chip photodetection.

A science and technology roadmap for graphene, related two-dimensional crystals, other 2d materials, and hybrid systems was put together in a joint effort by over 60 academics and industrialists. The roadmap covers the next 10 years and beyond, and its objective is to guide the research community and industry toward the development of products based on graphene and related materials.

The roadmap highlights three broad areas of activity. The first task is to identify new layered materials, assess their potential, and develop reliable, reproducible and safe means of producing them on an industrial scale. Identification of new device concepts enabled by 2d materials is also required, along with the development of component technologies. The ultimate goal is to integrate components and structures based on 2d materials into systems capable of providing new functionalities and application areas.

A team of international researchers at the Department of Energy’s SLAC National Accelerator Laboratory examined the properties of materials that combine graphene with a common type of semiconducting polymer and found that a thin film of the polymer transported electric charge better when grown on a single layer of graphene than it does when placed on a thin layer of silicon.

The scientists claim that their study is one of the first to measure the charge transport in these materials in the vertical direction the direction that charge travels in organic photovoltaic devices like solar cells or in light-emitting diodes. A somewhat surprising result of the study was that a polymer film about 50 nanometers thick conducted charge about 50 times better when deposited on graphene than the same film about 10 nanometers thick.

Researchers at the University of Illinois at Urbana-Champaign developed a single-step process to achieve 3D texturing of graphene and graphite, using a commercially available thermally activated shape-memory polymer substrate. 

Since crumpled graphene was shown to have modulated electrical and optical properties, finding methods to produce folded/crumpled graphene surfaces can be helpful for various applications, like electronics and biomaterials, electrodes for battery and supercapacitor applications, coating layers, omniphobic/anti-bacterial surfaces for advanced coating applications and more.

Researchers at the Virginia Commonwealth University and universities in China and Japan suggested a new carbon allotrope called "penta-graphene" (a five-sided variation on the familiar six-sided graphene structure), speculated to have several advantages compared to traditional graphene.

Currently in the computer modelling phase, the material appears to be dynamically, thermally and mechanically stable. The researchers claim that the material might outperform graphene in certain applications, as it would be mechanically stable, possess very high strength, and be capable of withstanding temperatures of up to 1,000 degrees Kelvin.