1. School of Chemistry & Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
2. Department of Chemistry & Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
3. School of Electrical & Computer Engineering and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0250, United States