Acknowledgments
This project was nancially supported by Ministry of Science
and Technology, Taiwan (MOST 1022221E009119 & 1032221
E009063MY2) and a research grant of National Chiao Tung
University in 2014. We acknowledge the instrumental support of
Organic ElectroOptical Materials and Devices Laboratory and
Center for Micro/Nano Science and Technology at National Cheng
Kung University and National Nano Device Laboratory, Taiwan.