1. School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore) http://www.ntu.edu.sg/home/hzhang/
2. Singapore‐Jiangsu Joint Research Center for Organic/Bio‐Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing Tech University, Nanjing 211816 (China)
3. Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)