1. Solar Energy Laboratory, Department of Electrical and Electronic Engineering, University of Rajshahi, Rajshahi 6205, Bangladesh
2. Department of Physics, University of Rajshahi, Rajshahi 6205, Bangladesh
3. Department of Materials Science and Engineering, University of Rajshahi, Rajshahi 6205, Bangladesh
4. Department of Chemistry, University of Rajshahi, Rajshahi 6205, Bangladesh
5. Department of Materials Science & Engineering, Clemson University, Clemson, South Carolina 29634-0971, United States