1. Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper DisplaysSouth 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. Physics of Complex FluidsFaculty of Science and TechnologyMESA+ Institute for NanotechnologyUniversity of Twente Enschede 7500AE The Netherlands
4. Academy of Shenzhen Guohua Optoelectronics Shenzhen 518110 P. R. China