Nano graphite films to keep next-generation smartphones cool

October 13, 2020 //By Jean-Pierre Joosting
Kaust graphite films to keep next-generation smartphones cool
The high-density of electronics packed inside the latest smartphones can face challenging thermal issues leading researchers to develop nanometer-thick graphite films to keep such devices cool.

KAUST researchers have developed a fast and efficient way to make a carbon material that could be used to dissipate heat in electronic devices such as smartphones or any electronic device where heat is a challenge. This versatile material in the form of nanometer-thick graphite films 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. Further, the process 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.

Model for NGF growth with respect to the Ni surface topography. The variable number of graphene layers correlates with the orientation, size and boundaries of the Ni grains at the surface of the polycrystalline metal foil. Image courtesy of KAUST, Xavier Pita (© 2020).

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