1. Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
2. Department
of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
3. National
Center for Photovoltaics, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
4. Department of Metallurgical and Materials
Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
5. Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, United States