[1] Chinese Univ Hong Kong, Dept Phys, Shatin, Hong Kong, Peoples R China
[2] Sun Yat Sen Univ, State Key Lab Optoelect Mat & Technol, Sch Phys & Engn, Guangzhou 510275, Guangdong, Peoples R China
[3] Sun Yat Sen Univ, Guangdong Prov Key Lab Display Mat & Technol, Sch Phys & Engn, Guangzhou 510275, Guangdong, Peoples R China