1. Department
of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
2. Center
for Polymers and Organic Solids, University of California—Santa Barbara, Santa Barbara, California 93106, United States
3. Material
Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
4. Organic
and Carbon Electronics Laboratory, Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States
5. Analytical
Instrumentation Facility, North Carolina State University, Raleigh, North Carolina 27695, United States