1. Optoelectronic Device Laboratory, School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
2. Institute for Energy Efficiency, University of California, Santa Barbara, Santa Barbara, California 93106, United States
3. Center for Optoelectronics Materials and Devices, Korea Institute of Science and Technology, Seoul, 02792, South Korea
4. Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States
5. Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong