1. School of Materials and Energy Guangdong University of Technology Guangzhou 510006 China
2. The Molecular Foundry Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
3. School of Physics and Optoelectronic Engineering Guangdong University of Technology Guangzhou 510006 China
4. State Key Laboratory of Luminescent Materials and Devices Institute of Polymer Optoelectronic Materials and Devices South China University of Technology Guangzhou 510640 China