1. Department of Chemistry; The Hong Kong University of Science and Technology; Clear Water Bay Kowloon Hong Kong
2. Department of Electronic Engineering; The Chinese University of Hong Kong; Shatin New Territories Hong Kong
3. Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials; Department of Physics; Jinan University; Guangzhou Guangdong 510632 China
4. Department of Applied Physics; The Hong Kong Polytechnic University; Hung Hom Kowloon Hong Kong