1. Chinese Academy of Sciences (CAS) Center for Excellence in NanoscienceBeijing 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. i‐LabSuzhou Institute of Nano‐Tech and Nano‐BionicsChinese Academy of Sciences Suzhou 215125 P. R. China
4. State Key Laboratory of Applied OpticsChangchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of Sciences Changchun 130033 P. R. China
5. Stanford University School of Medicine Palo Alto CA 94304 USA
6. Center of Nanoenergy ResearchSchool of Physical Science and TechnologyGuangxi University Nanning 530004 P. R. China
7. School of Materials Science and EngineeringGeorgia Institute of Technology Atlanta GA 30332‐0245 USA