1. Department of Chemistry, Tsinghua University, Beijing 100084, China
2. Key Laboratory of Research on Chemistry and Physics of Optoelectronic Materials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002,
China
3. State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084,
China
4. Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin, Heilongjiang 150080,
China
5. Department of Mathematics and Materials Research Institute, The Pennsylvania State University, University Park,
Pennsylvania 16802, USA