1. State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, P. R. China
2. Department of Physics, Hong Kong Baptist University, Hong Kong SAR 999077, P. R. China
3. School of Optics and Technology, Beijing Institute of Technology, Beijing 100081, P. R. China
4. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication; CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
5. State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, P. R. China