1School of Semiconductor and Chemical Engineering, Chonbuk National University, Jeonju 561-756, Republic of Korea
2Korea Printed Electronics Center, Korea Electronics Technology Institute, Jeonju 561-844, Republic of Korea
3Advanced Materials Division, Korea Research Institute of Chemical Technology, Daejeon 305-600, Republic of Korea
4Department of Nano and Chemical Engineering, Kunsan National University, Kunsan 751-701, Republic of Korea
5Korea Institute of Science Technology (KIST), Wanju-gun, Jeollabuk-do 565-902, Republic of Korea
6Heeger Center for Advanced Materials, Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea