1. Department of Electrical Engineering, Center for Advanced Photovoltaics, South Dakota State University, Brookings, South Dakota 57007, United States
2. Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
3. Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India