Next-gen smartphones to keep their cool

October 07, 2020

The powerful electronics packed inside the latest smartphones can be a significant challenge to keep cool. KAUST researchers have developed a fast and efficient way to make a carbon material that could be ideally suited to dissipating heat in electronic devices. This versatile material could also have additional uses ranging from gas sensors to solar cells.

Many electronic devices use graphite films to draw away and dissipate the heat generated by their electronic components. Although graphite is a naturally occurring form of carbon, heat management of electronics is a demanding application and usually relies on use of high-quality micrometer-thick manufactured graphite films. "However, the method used to make these graphite films, using polymer as a source material, is complex and very energy intensive," says G. Deokar, a postdoc in Pedro Costa's lab, who led the work. The films are made in a multistep process that requires temperatures of up to 3200 degrees Celsius and which cannot produce films any thinner than a few micrometers.

Deokar, Costa and their colleagues have developed a quick, energy-efficient way to make graphite sheets that are approximately 100 nanometers thick. The team grew nanometer-thick graphite films (NGF) on nickel foils using a technique called chemical vapor deposition (CVD) in which the nickel catalytically converts hot methane gas into graphite on its surface. "We achieved NGFs with a CVD growth step of just five minutes at a reaction temperature of 900 degrees Celsius," Deokar says.

The NGFs, which could be grown in sheets of up to 55 square centimeters, grew on both sides of the foil. It could be extracted and transferred to other surfaces without the need of a polymer supporting layer, which is a common requirement when handling single-layer graphene films.

Working with electron microscopy specialist Alessandro Genovese, the team captured cross-sectional transmission electron microscopy (TEM) images of the NGF on nickel. "Observing the interface of the graphite films to the nickel foil was an unprecedented achievement that will shed additional light on the growth mechanisms of these films," Costa says.

In terms of thickness, NGF sits between commercially available micrometer-thick graphite films and single-layer graphene. "NGFs complement graphene and industrial graphite sheets, adding to the toolbox of layered carbon films," Costa says. Due to its flexibility, for example, NGF could lend itself to heat management in flexible phones now starting to appear on the market. "NGF integration would be cheaper and more robust than what could be obtained with a graphene film," he adds.

However, NGFs could find many applications in addition to heat dissipation. One intriguing feature, highlighted in the TEM images, was that some sections of the NGF were just a few carbon sheets thick. "Remarkably, the presence of the few-layer graphene domains resulted in a reasonable degree of visible light transparency of the overall film," Deokar says. The team proposed that conducting, semitransparent NGFs could be used as a component of solar cells, or as a sensor material for detecting NO2 gas. "We plan to integrate NGFs in devices where they would act as a multifunctional active material," Costa says.
-end-


King Abdullah University of Science & Technology (KAUST)

Related Carbon Articles from Brightsurf:

The biggest trees capture the most carbon: Large trees dominate carbon storage in forests
A recent study examining carbon storage in Pacific Northwest forests demonstrated that although large-diameter trees (21 inches) only comprised 3% of total stems, they accounted for 42% of the total aboveground carbon storage.

Carbon storage from the lab
Researchers at the University of Freiburg established the world's largest collection of moss species for the peat industry and science

Carbon-carbon covalent bonds far more flexible than presumed
A Hokkaido University research group has successfully demonstrated that carbon-carbon (C-C) covalent bonds expand and contract flexibly in response to light and heat.

Metal wires of carbon complete toolbox for carbon-based computers
Carbon-based computers have the potential to be a lot faster and much more energy efficient than silicon-based computers, but 2D graphene and carbon nanotubes have proved challenging to turn into the elements needed to construct transistor circuits.

Cascades with carbon dioxide
Carbon dioxide (CO(2)) is not just an undesirable greenhouse gas, it is also an interesting source of raw materials that are valuable and can be recycled sustainably.

Two-dimensional carbon networks
Lithium-ion batteries usually contain graphitic carbons as anode materials. Scientists have investigated the carbonic nanoweb graphdiyne as a novel two-dimensional carbon network for its suitability in battery applications.

Can wood construction transform cities from carbon source to carbon vault?
A new study by researchers and architects at Yale and the Potsdam Institute for Climate Impact Research predicts that a transition to timber-based wood products in the construction of new housing, buildings, and infrastructure would not only offset enormous amounts of carbon emissions related to concrete and steel production -- it could turn the world's cities into a vast carbon sink.

Investigation of oceanic 'black carbon' uncovers mystery in global carbon cycle
An unexpected finding published today in Nature Communications challenges a long-held assumption about the origin of oceanic black coal, and introduces a tantalizing new mystery: If oceanic black carbon is significantly different from the black carbon found in rivers, where did it come from?

First fully rechargeable carbon dioxide battery with carbon neutrality
Researchers at the University of Illinois at Chicago are the first to show that lithium-carbon dioxide batteries can be designed to operate in a fully rechargeable manner, and they have successfully tested a lithium-carbon dioxide battery prototype running up to 500 consecutive cycles of charge/recharge processes.

How and when was carbon distributed in the Earth?
A magma ocean existing during the core formation is thought to have been highly depleted in carbon due to its high-siderophile (iron loving) behavior.

Read More: Carbon News and Carbon Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.