[1] Yunnan Univ, Natl Ctr Int Res Photoelect & Energy Mat, Yunnan Key Lab Micro Nano Mat & Technol, Sch Mat & Energy, Kunming 650091, Peoples R China
[2] Kunming Inst Phys, Kunming 650223, Peoples R China
[3] Yunnan Univ, Dept Phys, Kunming 650091, Peoples R China
[4] Harbin Inst Technol, Sch Mat Sci & Engn, Harbin 150001, Peoples R China