Friday 15, February 2013; 3:00 p.m.; Chem 200

Dr. Alex Sinitskii
Assistant Professor, Department of Chemistry,
University of Nebraska-Lincoln

Presents:

“Narrow Graphene Nanoribbons for Electronics and Photovoltaics”

Graphene, a two-dimensional carbon allotrope, is often considered as a complement or even replacement for silicon in many electronics applications. However, the absence of an electronic bandgap in graphene prevents its use in logic devices. According to theoretical studies, a bandgap compared to that in silicon (1.1 eV) could be found in narrow graphene nanoribbons (GNRs) that have atomically precise armchair edges and widths less than 2 nm. In this seminar, I will compare different top-down and bottom-up approaches that are often used for the fabrication of GNRs. The top-down approaches, such as a combination of electron-beam lithography and dry etching, sonochemical method, nanowire lithography, and unzipping of carbon nanotubes, typically yield ribbons with widths > 10 nm and disordered edges. In contrast, emergingbottom-uptechniques allow fabrication of GNRs that are less than 2 nm wide and have atomically precise edges, but they are typically too short for practical device fabrication.

In the second part of my talk, I will discuss a recently developed bottom-up approach for gram quantities of narrow GNRs, which yields ribbons that are less than 2 nm wide, have atomically precise armchair edges, and could be > 1 µm long. Such synthetic GNRs could be conveniently deposited from solution on any substrate, such as Si/SiO2, mica and Au(111), for further studies. These GNRs have a bandgap of about 1.4 eV, which is comparable to that in silicon (1.1 eV), making them promising for applications in field-effect transistors with high on-off ratios. Also, since these GNRs could be synthesized in gram quantities and at a very high yield, they could be used for bulk applications, including different coatings, composites and photovoltaic devices.