1. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, Guangdong 518060, China
2. Department of Chemistry, Korea University, Seoul 02841, Korea
3. Asan Medical Center, College of Medicine, University of Ulsan, Seoul 138-736, Korea
4. The School of East-West Medical Science, Kyung Hee University, Yongin, Gyeonggi-do 17104, Korea