1. Department of Materials Science and Engineering & Center for Functional Photonics (CFP), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong S.A.R.
2. Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstrassse 5-13 (D), 81377 Munich, Germany
3. Center for Advanced Materials, Qatar University, P.O. Box 2713, Doha, Qatar