1. Heeger Center for Advanced Materials, School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea
2. Department of Material Science and Engineering, Center for Advanced Molecular Photovoltaics (CAMP), Stanford University, Stanford, California 94305, United States
3. Convergence Components and Materials Research Laboratory, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeongno, Yuseong-gu, Daejeon 305-700, Republic of Korea
4. Department of Chemical Engineering, Hanbat National University, 16-1 Dukmyung-dong, Yuseong-gu, Daejeon 305-719, Republic of Korea
5. Research Institute for Solar and Sustainable Energies, Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea