1. School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245, United States
2. Department of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China
3. Key Laboratory of Science & Technology of Eco-Textile, College of Textiles, Donghua University, Shanghai 201620, China
4. Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China