Synthesis and Enhancement of Graphene for Optoelectronic Devices

Students: Michael Newburger (Physics) and Rachael Teuschler (ECE)

Advisor: Paul Berger (ECE)

Abstract: Following the fading hype and attention of the 2010 Nobel Prize for Physics awarded for the discovery of graphene, how to efficaciously leverage its unique properties has remained elusive. But graphene could soon be effective for vertical transport applications in economical plastic solar cells as a thin, flexible, highly solar transparent replacement of current, rigid indium tin oxide (ITO) anodes which require a rapidly depleting Indium resource. Our team has focused on facile ways to synthesize graphene with reduced catalyst wastage, and scalable roll-to-roll methods for exfoliation and attachment to the solar cell mechanical support. Our goal is to synthesize continuous graphene sheets, atomically thin and wrinkle-free, with conductivities exceeding 20 Ω/□ and optical transparency exceeding 92%, explore multiple transfer methods promoting material conservation and structural integrity, measure the sheet resistance and optical transmission of transferred graphene, and explore chemical doping methods of the graphene structure for improved photovoltaic efficiency. We have grown graphene by chemical vapor deposition on a home-built reactor maintained solely by this team, on nickel and copper foils and have transferred this graphene onto quartz slides by direct stamp, chemical etch and electro-chemical transfer methods. The grown and transferred graphene structures have been identified and characterized by Raman Spectroscopy, a key indicator of sp2 carbon bonding, proving our ability to grow and transfer graphene on a large scale for industrial production. Sheet resistance will now be measured by depositing contacts and using a four point probe method and full construction of a photovoltaic cell will allow for plastic solar cell efficiency testing. Understanding graphene’s properties and structure doping allows for the creation of economical, more efficient photovoltaic cells, expanding the market for point-of-use solar power attached to clothing, backpacks, or conformally coating curved automobiles, unlike brittle silicon cells.

Booth: 244