1. Department of Chemistry, University of California, Berkeley, CA 94720, USA.
2. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
3. School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
4. Department of Physics, University of California, Berkeley, CA 94720, USA.
5. Kavli Energy NanoScience Institute, Berkeley, CA 94720, USA.
6. Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
7. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA.