1. Laboratory of Advanced Optoelectronic MaterialsCollege of Chemistry, Chemical Engineering and Materials ScienceSoochow University Suzhou 215123 China
2. Department of Physics and Astronomy and Collaborative InnovationCenter of IFSA (CICIFSA)Shanghai Jiaotong University Shanghai 200240 China
3. Materials Sciences DivisionLawrence Berkeley National Laboratory Berkeley CA 94720 USA
4. Beijing National Laboratory for Molecular SciencesCAS Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of Sciences Beijing 100190 China