1. Division of Physics and Applied Physics; School of Physical and Mathematical Sciences; Nanyang Technological University; 637371 Singapore
2. Energy Research Institute @ NTU (ERI@N); Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
3. Singapore-Berkeley Research Initiative for Sustainable Energy; 1 Create Way Singapore 138602 Singapore
4. NOVITAS, Nanoelectronics Centre of Excellence; School of Electrical and Electronic Engineering; Nanyang Technological University; Singapore 639798