1. Division of NanophotonicsCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology Beijing 100190 China
2. University of ChineseAcademy of Sciences Beijing 100049 P. R. China
3. State Key Laboratory of Optoelectronic Materials and TechnologiesGuangdong Province Key Laboratory of Display Material and TechnologySchool of Electronics and Information TechnologySun Yat‐sen University Guangzhou 510275 China