1. School of Materials Science
and Engineering, Nanyang Technological University, Singapore 637553
2. Energy Research Institute@NTU
(ERI@N), Interdisciplinary Graduate School, Singapore 637553
3. Division of Physics and
Applied Physics, School of Physical and Mathematical Sciences, Singapore 637371
4. Energy Research Institute@NTU
(ERI@N), Nanyang Technological University, Singapore 637553