1. School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
2. Nanoscale Device Characterization Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
3. Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
4. Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States