Graphene sheets are most commonly created using chemical vapor deposition, in which a copper foil is exposed to methane gas at high temperatures (over 1000-degrees Celsius). During the process, carbon breaks free from the methane and comes to rest on the surface of the copper foil, resulting in the one atom-thick honeycomb lattice we’ve come to associate with graphene.
Removing the graphene from the foil is challenging work, however, which is one of the obstacles to wider-scale commercial production of graphene sheets. New research from a joint U.S./UK/Singapore research team, recently published in Advanced Functional Materials, may have discovered a new and better method.
“Normally, transferring a monolayer graphene from the copper foils into the substrates is challenging and results in many defects and wrinkles,” said Dr. Mohammad Mahdi Tavakoli of the Massachusetts Institute of Technology (MIT), and lead author of the publication. “In this regard, Roll-to-Roll (R2R) transfer process is a critical step for scaling up and commercialization of graphene.”
The researchers used a polymer called parylene, often used in aerospace and biomedicine, to improve the quality and conductivity of the transferred graphene. The team demonstrated the method by making thin-film solar cells using their graphene layer in place of one of the cell’s electrodes along with a parylene layer.