1. Department of Chemistry, Rice University, Houston, Texas 77005, United States
2. Applied Physics Graduate Program, Rice University, Houston, Texas 77005, United States
3. Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
4. ARC Centre of Excellence in Exciton Science, School of Mathematics and Statistics, The University of Melbourne, Parkville, VIC 3010, Australia
5. Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
6. Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States