1. Graphene Research Center, KAIST Institute of NanoCentury, School of Mechanical, Aerospace and Systems Engineering, Division of Ocean Systems Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
2. A. G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75080, United States
3. Faculty of Applied Chemical Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, Republic of Korea
4. Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 4009 Jonsson Engineering Center, Troy, New York 12180, United States