1. LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, the Photonics Institute, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
2. ARC Centre of Excellence in Exciton Science, Department of Materials Science and Engineering, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
3. Department of Electrical and Electronics Engineering, Department of Physics, UNAM─Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey