Ultra-thin graphite films soak up heat to keep smartphones cool
Making every micrometer count is a key consideration for designers and engineers working on modern smartphones, and a new material could free up some valuable space. Scientists have developed a nanometer-thick form of graphite that helps keep electronic devices cool, and does so while taking up just a fraction of the real estate of current solutions.
Graphite films play an important role in keeping many electronic devices cool, with their excellent thermal conductivity used to neutralize the heat produced by the surrounding components. But they aren’t so easy to make, involving a multistep process where the material is subjected to extreme temperatures of up to 3,200 °C (5,792 °F) to produce films measuring around a few micrometers thick.
“The method used to make these graphite films, using polymer as a source material, is complex and very energy intensive,” says G. Deokar, who led the new research.
Deokar and his colleaques at Saudi Arabia’s King Abdullah University of Science and Technology (KAUST) have been working on a more efficient way to produce these graphite cooling devices. The technique involves using nickel foils as a catalyst to turn hot methane gas into graphite. The graphite films that form on the surface of the nickel foils measure just 100 nanometers thick. For reference, 1,000 nanometers make up 1 micrometer.
These sheets, which the team calls nanometer-thick graphite films (NGFs), were produced by subjecting the material to temperatures of around 900 °C (1,652 °F). The process sees NGFs form on either side of the foil, which can be grown in sheets measuring up to 55 sq cm (8.52 in). These sheets can in turn be extracted and transferred to other surfaces.
These NGFs are far thinner than the micrometer-thick graphite films currently used, but still far thicker than single-layer graphene. It may occupy a sweet spot in this way, according to the researchers, offering a degree of flexibility and robustness offered by neither of those materials, while being cheaper to produce.
“NGFs complement graphene and industrial graphite sheets, adding to the toolbox of layered carbon films,” Costa says.
These conductive and semi-transparent sheets could be used for more than just keeping mobile devices cool. The researchers say their versatile nature could see them used as components for solar cells or for sensors that detect NO2 gas.
“We plan to integrate NGFs in devices where they would act as a multifunctional active material,” Costa says.