1. Guangdong Provincial Key Laboratory of Information Photonics Technology, School of Material and Energy, Guangdong University of Technology, Guangzhou 510006, P. R. China
2. Department of Chemistry, University of Hull, Cottingham Road, Hull, Yorkshire HU6 7RX, UK
3. Center of Bio and Micro/Nano Functional Materials, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
4. Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates (South China University of Technology), Guangzhou 510640, P. R. China