1. Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
2. Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
3. National Center for Photovoltaics, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
4. Center for Nanoscale Systems, Harvard University, Cambridge, Massachusetts 02138, United States
5. Materials Research Laboratory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
6. Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
7. Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
8. Department of Physics, University of Virginia, Charlottesville, Virginia 22904, United States