1. Guangdong Province Key Laboratory of Display Material and Technology, State Key Laboratory of Optoelectronic Material and Technology, School of Electronics and Information Technology; Sun Yat-sen University; Guangzhou P. R. China
2. State Key Laboratory on Advanced Displays and Optoelectronics Technologies; The Hong Kong University of Science and Technology; Clear Water Bay Hong Kong
3. Engineering Department; University of Cambridge; Cambridge United Kingdom CB3 0FA