1. Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States
2. Organic
and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, North Carolina 27695, United States
3. Department
of Physics and Astronomy, Appalachian State University, Boone, North Carolina 28608, United States
4. Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States