[1] Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA
[2] Sichuan Univ, Polymer Res Inst, State Key Lab Polymer Mat Engn, Chengdu 610065, Peoples R China
[3] Chongqing Univ, Dept Optoelect Engn, Chongqing 400044, Peoples R China
[4] Chinese Acad Sci, Beijing Inst Nanoenergy & Nanosyst, Beijing 100083, Peoples R China