1. Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, Unites States
2. Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, Unites States
3. Center for Materials, Devices and Integrated Systems, Rensselaer Polytechnic Institute, Troy, New York 12180, Unites States