1. Department of Electrical and Electronics Engineering, BITS Pilani Hyderabad Campus, Hyderabad 500078, Telangana, India
2. Center for Energy Harvesting Materials and Systems, Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
3. Department of Physics, BITS Pilani Hyderabad Campus, Hyderabad 500078, Telangana, India