1. Department of Physics, University of California, Berkeley, California 94720, United States
2. Department
of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
3. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
4. Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
5. Department of Chemistry, University of California, Berkeley, California 94720, United States
6. The
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States