1. Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education Jilin Normal University Changchun 130103 P. R. China
2. Department of Chemical Engineering Waterloo Institute for Nanotechnology Waterloo Institute for Sustainable Energy University of Waterloo Waterloo Ontario N2L 3G1 Canada
3. South China Academy of Advanced Optoelectronics International Academy of Optoelectronics at Zhaoqing South China Normal University Guangzhou 510006 P. R. China