1. Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
2. School of Electronic Information, Huanggang Normal University, Huanggang 438000, China
3. Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China
4. Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States