1. College of Physics; Qingdao University; Qingdao 266071 China
2. College of Electronic and Information Engineering; Qingdao University; Qingdao 266071 China
3. Lab of New Fiber Materials and Modern Textile; Growing Base for State Key Laboratory; Qingdao University; Qingdao 266071 China
4. Department of Materials Science/CENIMAT-I3N; Faculty of Sciences and Technology; New University of Lisbon and CEMOP-UNINOVA; Campus de Caparica 2829-516 Caparica Portugal