1. State Key Laboratory of Luminescent Materials and Devices Institute of Polymer Optoelectronic Materials and Devices School of Materials Science and Engineering South China University of Technology Guangzhou 510640 P. R. China
2. School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics Georgia Institute of Technology Atlanta GA 30332‐0400 USA
3. Department of Chemistry and Biochemistry The University of Arizona Tucson 85721 USA
4. Department of Materials Science and Engineering City University of Hong Kong Kowloon 999077 Hong Kong
5. School of Energy and Environment City University of Hong Kong Kowloon 999077 Hong Kong