1. Department of Materials Science, Università di Milano-Bicocca, via Cozzi 55, 20125 Milan, Italy
2. CNR-IFN, L-NESS, via Anzani 42, I-22100 Como, Italy
3. School of Chemistry and Biochemistry, Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
4. Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Center of Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
5. Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO 80303, USA
6. Department of Chemical and Biological Engineering, Department of Chemistry, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO 80303, USA
7. Center for Polymers and Organic Solids, Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA