1. Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA.
2. Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
3. Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR.
4. Center for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA.
5. Department of Electrical, Computer, and Energy Engineering and Materials Science and Engineering Program, University of Colorado, Boulder, CO 80309, USA.
6. Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO 80309, USA.