a
Department of Physics and Astronomy, 6100 Main Street, Houston, USA
b
Department of Chemical and Biomolecular Engineering, 6100 Main Street, Houston, USA
E-mail: mp@rice.edu
c
Department of Chemistry, R. E. Smalley Institute for Nanoscale Science & Technology, Rice University, 6100 Main Street, Houston, USA
e
Materials Science and Engineering Graduate Program, and Liquid Crystal Materials Research Center, University of Colorado, 2000 Colorado Ave, Boulder, USA
f
Renewable and Sustainable Energy Institute, University of Colorado and National Renewable Energy Laboratory, Boulder, USA