1. Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 P. R. China
2. National Center for International Research on Green OptoelectronicsSouth China Normal University Guangzhou 510006 P. R. China
3. Shenzhen Guohua Optoelectronics Tech. Co. Ltd. Shenzhen 518110 China
4. Academy of Shenzhen Guohua Optoelectronics Shenzhen 518110 China