1. Beijing Key Laboratory for Optical Materials and Photonic DevicesDepartment of ChemistryCapital Normal University Beijing 100048 P. R. China
2. Tianjin Key Laboratory of Molecular Optoelectronic SciencesDepartment of ChemistryTianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin 300072 P. R. China