Novel Form of Graphene-Based Metamaterial

Schematic of graphene-based metamaterial absorber. (Source: U. Sydney / NPG)

Researchers at the University of Sydney, Swinburne Univer­sity of Tech­nology and the Australian National Univer­sity have colla­borated to develop a solar absorbing, ultrathin film with unique properties that has great potential for use in solar thermal energy harvesting. The 90-nanometre material can be rapidly heated up to 160 degrees under natural sunlight in an open environment.

This new graphene-based material also opens new avenues in thermo­photovoltaics, solar seawater desalination, infrared light source and heater, optical components as modulators and inter­connects for communication devices and photo­detectors. It could even lead to the development of invisible cloaking technology through developing large-scale thin films enclosing the objects to be hidden. Martijn De Sterke from the Univer­sity of Sydney Nano Institute said: “Through our colla­boration we came up with a very innovative and successful result. We have developed a new class of optical material, the properties of which can be tuned for multiple uses.”

The researchers have developed a 2.5cm x 5cm working prototype to demonstrate the photo-thermal performance of the graphene-based metamaterial absorber. They have also proposed a scalable manufacture strategy to fabricate the proposed graphene-based absorber at low cost. “This is among many graphene inno­vations in our group,” said Baohua Jia, Research Leader, Nano­photonic Solar Technology, in Swinburne’s Centre for Micro-Photonics. “In this work, the reduced graphene oxide layer and grating structures were coated with a solution and fabricated by a laser nanofabri­cation method, which are both scalable and low cost.”

“Our cost-effective and scalable graphene absorber is promising for integrated, large-scale appli­cations, such as energy-harvesting, thermal emitters, optical inter­connects, photo­detectors and optical modulators,” Han Lin, Senior Research Fellow at Swinburne’s Centre for Micro-Photonics. “Fabri­cation on a flexible substrate and the robust­ness stemming from graphene make it suitable for industrial use,” Keng-Te Lin, another researcher from Swinburne, said. “The physical effect causing this outstanding absorption in such a thin layer is quite general and thereby opens up a lot of exciting appli­cations,” said Bjorn Sturmberg, who completed his PhD in physics at the University of Sydney in 2016. (Source: U. Sydney)

Reference: H. Lin et al.: A 90-nm-thick graphene metamaterial for strong and extremely broadband absorption of unpolarized light, Nat. Phot. 13, 270 (2019); DOI: 10.1038/s41566-019-0389-3

Link: Centre for Micro-Photonics, Swinburne University of Technology, Hawthorn, Australia

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