a
Key Laboratory for Organic Electronics & Information Displays, Institute of Advanced Materials, Nanjing University of Posts & Telecommunications, Nanjing 210046, China
E-mail: wei-huang@njupt.edu.cn
;
Fax: (+)86 25 8586 6999
b
Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, China