Researchers from the Massachusetts Institute of Technology (MIT) have developed a new process for creating large pieces of ultra-thin graphene that could lead to new classes of devices that emit and harvest light.
Scientists for years have been searching for a better way to make large sheets of thin, transparent electrodes for use in electronics like computer and smartphone screens and solar cells. The standard for doing so today involves a material called indium tin oxide (ITO) due to its electrical conductivity and optical transparency but it has its shortcomings. Namely, it is based on expensive elements.
Graphene has emerged as a prime candidate to replace ITO as it is an excellent electrical conductor, is very thin and incredibly flexible. Best yet, it can easily be grown in the laboratory through a process called chemical vapor deposition (CVD) which uses copper as a seed layer.
The problem, however, is that it is very difficult to separate the CVD-grown graphene from the copper substrate. During this stage, the graphene sheets often develop tears and wrinkles that reduce electrical conductivity.
By using a buffer layer comprised of a polymer material called parylene, the researchers demonstrated the ability to reliably manufacture large-area graphene sheets that “maintain the electrical and mechanical properties of the pristine graphene,” said Giovanni Azzellino, an MIT postdoc that worked on the project.
The buffer material is already widely used in microelectronics meaning supply chains and equipment to develop and handle it are already plentiful. What’s more, the entire process should be relatively easy to scale up for industrial production. Best yet, the graphene “comes for almost free,” Azzellino added.