1. State Key Lab of Crystal Materials, Shandong University, Jinan 250100, P.R. China
2. School of Physics, Shandong University, Jinan 250100, P.R. China
3. School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, P.R. China
4. Key Laboratory for Special Functional Aggregated Materials of Education Ministry, School of Chemistry & Chemical Engineering, Shandong University, Jinan 250100, P.R. China
5. School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States