UK-based collaboration works to develop graphene ultra-barrier materials

The Centre of Process Innovation (CPI) recently announced it was part of a UK-based collaboration with University of Cambridge, FlexEnable Ltd., and the National Physical Laboratory. The goal of the partnership was to develop ultra-barrier materials using graphene, to create flexible, transparent electronic-based plastic displays for smartphones, tablets, and wearable electronics. Manufacturers of these products require barriers with a greater degree of flexibility, which graphene can likely provide.

FlexEnable, the lead business partner, saw many uses for the graphene ultra-barrier materials.

Graphene-based barrier coatings and films could be used for flexible OLED lighting and LED encapsulants as well as display products, on a widespread commercial basis.

Using graphene interlayers, displays can be made very flexibly. The barrier materials will be transparent, robust, and impervious to various molecules that could cause damage. This represents a great increase in potential for the technology in various applications and industries, which use barrier coatings and films but require a greater degree of flexibility and strength.

At the time the collaboration was announced, James Johnstone, Business Development Manager at CPI, said, “The collaboration brings together world class supply chain expertise across the UK to bridge the gap from Graphene research to the manufacturing of commercial flexible display screens. The Hofmann group at the Department of Engineering in Cambridge is a key innovator in the growth and processing of graphene films. NPL are experts in the traceable measurement of water transfer characteristics and FlexEnable brings an industrial focus to the project with their extensive expertise in the manufacture of flexible electronics and flexible display screens in particular. CPI’s role in the project is to use roll-to-roll atomic layer deposition technologies to scale up, test and fabricate the ultra barrier materials.”

Also at the time the collaboration was announced, Chuck Milligan, CEO of FlexEnable added, “Graphene and other 2D materials are extremely relevant for the flexible electronics industry, with the potential for broad usage from conductors to semiconductors, insulators and even barriers. Building on FlexEnable’s previous leading-edge work with graphene, our involvement will enable the accelerated integration of these game-changing materials in a new generation of ultra-flexible end-user applications with innovative form factors.”

The partnership is hoping to bring their barrier coatings and materials onto the market for commercial use as soon as possible.

The International Technology Roadmap for Semiconductors believes that the post-silicon era will begin in about 2028 and Graphene is considered to be the revolutionary, replacement material.

The electron mobility of Graphene at room temperature is already more than 10 times that of silicon (15.000 cm2/Vs compared to 1,400 cm2/Vs). Researchers at the University of British Columbia (UBC) have now achieved infinity—superconductivity by doping Graphene with lithium and then cooling it to 5.9 degrees Kelvin.

UBC professor Andrea Damascelli, however, has hopes to push doped graphene into higher temperatures of criticality by augmenting the methods of his predecessors.

“Increasing the ultimate value of Tc achievable on monolayer graphene is at present our key goal,” Damascelli said. “We are exploring specific combinations of new substrates and dopants in order to further enhance and stabilize superconductivity, in much the same way that enhanced transition temperatures have been achieved in other two-dimensional quantum materials, such as single-layer FeSe.”

He has already begun experimenting with dopants in single atomic layers (monolayers) of graphene and has been measuring whether or not the adsorbed atoms diffuse over the surface and get stuck within the graphene lattice.

“The key advantages of one dopant versus the other are the easiness in donating the right amount of electrons to monolayer graphene, the stability of the adatoms on the graphene surface (some diffuse or intercalate more easily than others, which may be detrimental to stabilizing superconductivity), as well as the modification they induce in the interaction between electrons and atomic vibration of the graphene layer which in the end directly controls the strength of superconductivity and the value of the critical temperature. Finding the ideal dopants — the most stable and the ones leading to the highest Tc — is crucial for possible future applications.”

“Our monolayer graphene was epitaxially grown [under an argon atmosphere on hydrogen-etched silicon carbide substrates] by our collaborators at the Max Planck Institute in Stuttgart, in researcher Ulrich Starke’s group. These samples were reconditioned [annealed at 500 degrees Celsius] immediately before the angle resolved photo emission spectroscopy (ARPES) measurements in our chamber at UBC in the Quantum Materials Lab, to obtain atomically-clean pristine graphene,” Damascelli said. “Lithium adatoms were then deposited in ultra-high-vacuum conditions from a commercial alkali metal source, with the graphene samples held at a temperature of 8 degrees Kelvin. The low temperature turned out to be key in being able to decorate graphene with a well ordered Li-superstructure, which in turn is essential for observing superconductivity.”

Along with associates worldwide, the Damascelli group at UBC will tune the parameters of his doped graphene material in the hope of achieving superconductivity at room temperature and normal atmospheric pressures.

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