1. Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
2. Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
3. Adroit Materials, Inc., 2054 Kildaire Farm Rd., Cary, North Carolina 27518, USA
4. Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, North Carolina 27695, USA