1. Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80303, United States
2. Department of Materials Science and Engineering, and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, Raleigh, North Carolina 27695, United States
3. Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
4. Physics Department, Wellesley College, Wellesley, Massachusetts 02481, United States
5. Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80303, United States