1. Shenzhen Key Laboratory of Polymer Science and TechnologyCollege of Materials Science and EngineeringShenzhen University Shenzhen 518060 P. R. China
2. School of Chemical Engineering and Light IndustryGuangdong University of Technology Guangzhou 510006 P. R. China
3. Shenzhen Engineering Laboratory of Phosphorene and OptoelectronicsInternational Collaborative Laboratory of 2D Materials for Optoelectronic Science and TechnologyShenzhen University Shenzhen 518060 P. R. China
4. Key Laboratory of Advanced Technologies of Materials (Ministry of Education)School of Materials Science and EngineeringSouthwest Jiaotong University Chengdu 610031 P. R. China
5. Institute for Integrative NanosciencesIFW Dresden 01069 Dresden Germany
6. Material Systems for NanoelectronicsTechnische Universität Chemnitz 09107 Chemnitz Germany