1. Department of Chemistry, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, China (SAR)
2. Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, China (SAR)
3. MIIT Key Laboratory of Advanced Display Materials and Devices, Ministry of Industry and Information Technology, Institute of Optoelectronics & Nanomaterials, Nanjing University of Science and Technology, Nanjing 210094, China