Ultrathin graphene film offers new concept for solar energy

A collaborative team of researchers from Swinburne University of Technology, the University of Sydney and Australian National University has developed a solar-absorbing ultrathin film that has potential in solar-thermal energy harvesting. The 90 nm material is 1000 times finer than a human hair and can rapidly heat to temperatures as high as 160°C under natural sunlight in an open environment.

The research team has developed a 2.5 x 5 cm working prototype to demonstrate the photothermal performance of the graphene-based metamaterial absorber and has proposed a scalable manufacturing strategy to fabricate the graphene-based absorber at low cost.

“Our cost-effective and scalable graphene absorber is promising for integrated, large-scale applications that require polarisation-independent, angle-insensitive and broad-bandwidth absorption, such as energy harvesting, thermal emitters, optical interconnects, photodetectors and optical modulators,” explained lead author Dr Han Lin, Senior Research Fellow at Swinburne’s Centre for Micro-Photonics.

The technology has the potential to lead to ‘invisible cloaking technology’ via the development of large-scale thin films enclosing objects to be hidden. It is hoped that the new graphene-based material will also open new avenues in thermophotovoltaics (the direct conversion of heat to electricity), solar seawater desalination, infrared lighting and heating, optical components, modulators and interconnects for communication devices, photodetectors and colourful display.

“This is among many graphene innovations in our group,” said Professor Baohua Jia, Research Leader of Nanophotonic Solar Technology at 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, respectively, which are both scalable and low cost.”

Co-author Dr Keng-Te Lin added, “Fabrication on a flexible substrate and the robustness stemming from graphene make it suitable for industrial use.”

Professor Martijn de Sterke, Director of the Institute of Photonics and Optical Science, said, “Through our collaboration we came up with a very innovative and successful result. We have essentially developed a new class of optical material, the properties of which can be tuned for multiple uses.”

The research, published in Nature Photonics, has been funded by an Australian Research Council Discovery Project grant.

Image credit: ©swinburne.edu.au