1. Key Laboratory of Polar Materials and DevicesDepartment of Electronic ScienceSchool of Physics and Electronic ScienceEast China Normal University Shanghai 200241 P. R. China
2. School of Chemistry and Chemical EngineeringShanghai Jiao Tong University Shanghai 200025 P. R. China
3. Laboratory of Organic ElectronicsITNLinköping University Norrköping SE‐60174 Sweden
4. Center for Excellence in Nanoscience (CAS)Key Laboratory of Nanosystem and Hierarchical Fabrication (CAS)National Center for Nanoscience and Technology Beijing 100190 P. R. China
5. Collaborative Innovation Center of Extreme OpticsShanxi University Taiyuan Shanxi 030006 P. R. China