Monolayered Graphene Oxide as a Low Contact Resistance Protection Layer in Alkanethiol Solid-State Devices

• Published in: Journal of physical chemistry. C Vol. 122; no. 18; pp. 9731 - 9737
• Main Authors: Kühnel, Martin, Petersen, Søren V, Hviid, Rune, Overgaard, Marc H, Laursen, Bo W, Nørgaard, Kasper
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10.05.2018
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.7b12606

Vapor deposition of metals has long been the primary method for making contact with organic molecules in electronic devices in a fast and scalable manner. However, direct metal evaporation has proven to be the primary cause of device failure in solid-state molecular devices due to the degradation of the self-assembled molecular monolayers. The introduction of a protective interlayer between the molecular monolayer and the evaporated top electrode greatly improves the yield of working devices but at the cost of an increased internal contact resistance that depends on the nature of the interlayer and its interface with both organic molecules and metal top electrode. In the present work, we investigate the performance of a single layered graphene oxide as an atomically thin interlayer in solid-state molecular devices. We show that a single layered graphene oxide sheet is sufficient to protect an organic monolayer of alkane thiols from metal-induced degradation and short-circuiting. Remarkably, and despite graphene oxide being an insulating material, the contact resistance in our devices with a graphene oxide as a protective interlayer is similar to that of pure metal/molecule/metal junctions. We interpret this observation as graphene oxide effectively becoming part of the top electrode. The graphene oxide monolayer is thus a very promising candidate as a protective interlayer in solid-state molecular devices.