1. National Renewable Energy Laboratory, Golden, Colorado 80401, United States
2. Department
of Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
3. Department
of Electrical Engineering, University of Washington, Seattle, Washington 98195, United States
4. Renewable
and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80309 United States
5. Corning Research & Development Corporation, Corning, New York 14830, United States
6. Solid State
Physics Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, India