1. Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
2. School of Nano Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
3. Functional Materials and Device Laboratory, School of Energy Science & Engineering, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
4. School of Energy Science & Engineering, Indian Institute of Technology Kharagpur, Kharagpur-721302, India