Novel form of graphene-based optical material developed

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 is 1000 times finer than a human hair and 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 (the direct conversion of heat to electricity)
- solar seawater desalination
- infrared light source and heater
- optical components: modulators and interconnects for communication devices
- photodetectors
It could even lead to the development of invisible cloaking technology via large-scale thin films enclosing the objects to be hidden.
Professor Martijn De Sterke from the University of Sydney Nano Institute and School of Âé¶¹ÒùÔºics is Director of the Institute for Photonics and Optical Science. He 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 Professor 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," said first author of the research paper, Dr. 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," Dr. Keng-Te Lin, another author 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 Dr. Bjorn Sturmberg, who completed his Ph.D. in physics at the University of Sydney in 2016 and is now a lecturer at the Australian National University.
More information: Han Lin et al. A 90-nm-thick graphene metamaterial for strong and extremely broadband absorption of unpolarized light. Nature Photonics. March 18, 2019
Journal information: Nature Photonics
Provided by University of Sydney