Graphene-based thin film absorbs solar energy

Researchers at the University of Sydney, Swinburne University of Technology and the Australian National University (ANU) have collaborated to develop a solar-absorbing, ultrathin film that has great potential for use in solar thermal energy harvesting.

Described in the journal Nature Photonics, the 90 nm graphene metamaterial is 1000 times finer than a human hair and can be rapidly heated up to 160°C under natural sunlight in an open environment.

“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 study co-author Dr Bjorn Sturmberg, who completed his PhD at the University of Sydney and is now a lecturer at ANU.

The researchers suggest that the material opens new avenues in thermophotovoltaics (the direct conversion of heat to electricity); solar seawater desalination; infrared lighting and heating; optical componentry (modulators and interconnects for communication devices); and photodetection. It could even lead to the development of ‘invisible cloaking technology’ through developing large-scale thin films enclosing the objects to be ‘hidden’.

“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 Dr Han Lin, Senior Research Fellow at Swinburne’s Centre for Micro-Photonics and first author on the paper.

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

The researchers have developed a 2.5 x 5 cm working prototype to demonstrate the photothermal 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.

“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,” said Professor Baohua Jia, Research Leader, Nanophotonic Solar Technology, in Swinburne’s Centre for Micro-Photonics.

“This is among many graphene innovations in our group.”

Image caption: Schematic of the graphene-based metamaterial absorber. Source: Nature Photonics.

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