1. School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, and CREOL & FPCE, The College of Optics and Photonics and Department of Physics, University of Central Florida, Orlando, Florida 32816-2700