1. Beijing Key Laboratory of Micro‐nano Energy and SensorBeijing Institute of Nanoenergy and NanosystemsChinese Academy of Sciences Beijing 100083 P. R. China
2. School of Nanoscience and TechnologyUniversity of Chinese Academy of Sciences Beijing 100049 P. R. China
3. College of Optoelectronic EngineeringShenzhen University Shenzhen 518060 P. R. China
4. Department of Physics and Laboratory of Materials PhysicsZhengzhou University Zhengzhou 450001 P. R. China
5. Center on Nanoenergy ResearchSchool of Physical Science and TechnologyGuangxi University Nanning 530004 P. R. China