1. National and Local Joint Engineering Laboratory of Optical-Conversion Materials and Technology, and School of Materials and Energy, Lanzhou University, Lanzhou 730000, P.R. China
2. Institute for Advanced Study, and School of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, P.R. China
3. School of Stomatology, Lanzhou University, Lanzhou 730000, P. R. China