1. II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
2. Department of Chemistry, University of California, Berkeley, California 94720, United States
3. Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology (National Research University), 141700, Dolgoprudny, Russia
4. Russian Quantum Center, Skolkovo innovation city, 121205, Moscow, Russia
5. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
6. Kavli Energy NanoSciences Institute, University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States