1. Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education; Department of Chemistry; Tsinghua University; Beijing 100084 China
2. National Laboratory of Solid State Microstructures; College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures; Nanjing University; Nanjing 210093 China
3. State Key Laboratory for Mesoscopic Physics; Collaborative Innovation Center of Quantum Matter; School of Physics; Center for Nanochemisty; Peking University; Beijing 100871 China
4. Department of Chemical Engineering and Materials Science; University of California-Irvine; Irvine CA 92697 USA
5. Department of Physics and Astronomy; University of California-Irvine; Irvine CA 92697 USA