1. Center for Condensed Matter Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
2. Department of Materials Science and Engineering, National Taiwan University of Science and Technology (NTUST) 43, Sec. 4 Keelung Road, Taipei 10607, Taiwan
3. Center for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, United States
4. Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
5. Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan