1. College of Materials, Xiamen University, Simingnan-Road 422, Xiamen 361005, P. R. China
2. Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Yanchang Road 149, Shanghai 200072, P. R. China
3. China College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, P. R. China