1. Shenzhen Technology University; College of New Materials and New Energies; 3002 Lantian Road Shenzhen Guangdong 518118 PR China
2. Nanyang Technological University; School of Materials Science and Engineering; 50 Nanyang Avenue Singapore 639798 Singapore
3. Hong Kong Polytechnic University; Department of Applied Physics; 11 Yuk Choi Road Hung Hom, Kowloon Hong Kong
4. The University of New South Wales; School of Materials Science and Engineering; High Street Kensington, Sydney NSW 2052 Australia