1. Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
2. US Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States
3. Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
4. Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
5. Department of Materials Science, Graduate School of Engineering, Osaka Metropolitan University, Sakai, Osaka 599-8531, Japan