1. Department of Chemistry, and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois, 60208, USA
2. Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
3. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
4. Flexterra Corporation, 8025 Lamon Avenue, Skokie, Illinois 60077, USA