1. Department of Photovoltaics and Materials Technology, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
2. Department of Chemical and Biomolecular Engineering, The University of Tennessee Knoxville, Knoxville, Tennessee 37996, United States
3. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
4. Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States