For all the attention graphene gets thanks to its impressive list of properties, how many of us have actually encountered it in anything other than its raw graphite form? Show of hands. No-one? That's because it is still difficult to mass-produce without introducing defects. Now a team at the Korea Institute of Science and Technology (KIST) has developed a graphene substitute from plastic that offers the benefits of graphene for use in solar cells and semiconductor chips, but is easy to mass-produce.
The technique that currently shows the greatest potential for producing high quality graphene at large scales is chemical vapor deposition (CVD). This is a complicated eight-step process whereby gaseous reactants are deposited onto a metal film substrate that acts as a catalyst. Once the graphene is formed, it needs to be removed from the metal substrate and transferred to another board, such as a solar cell substrate, which runs the risk of wrinkling or cracking the graphene.
The KIST team claims the process used to produce its new synthesized carbon nanosheets is much simpler, involving a two-steps that are catalyst- and transfer-free. Based on the same continuous process used to mass-produce carbon fiber, the researchers say it also faces a much easier transition to full-scale commercialization. Furthermore, the team was able to show that the nanosheets can be used directly as transparent electrodes for organic solar cells without requiring any additional processing.
Put (very) simply, to produce carbon nanosheets with properties similar to graphene, the researchers spin-coated a polymer solution onto a quartz substrate and heat-treated it at 1,200° C (2,192° F). They claim that by eliminating the need for a metal substrate or for transferring the nanosheets to another board, they bypass the steps that are likely to lead to defects in the material.
"[The process] is expected to be applied for commercialization of transparent and conductive 2D carbon materials without difficulty since this process is based on the continuous and mass-produced process of carbon fiber," said Dr. Han Ik Joh who led the research team.
The team's work is detailed in a paper published in the journal Nanoscale.