1. State Key Laboratory on Integrated Optoelectronics; College of Electronic Science and Engineering; Jilin University; 2699 Qianjin Street Changchun 130012 China
2. Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 Groningen 9747 AG The Netherlands
3. Department of Macromolecular Science and Engineering; Graduate School of Science and Technology; Kyoto Institute of Technology; Matsugasaki Sakyo-ku Kyoto 606-8585 Japan
4. College of Physics; Jilin University; 119 Jiefang Road Changchun 130023 China