1. College of Materials Science and Engineering Hunan University Changsha Hunan 410082 P. R. China
2. State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen Fujian 361005 P. R. China
3. State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou Zhejiang 310027 P. R. China
4. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen 518060 P. R. China
5. Shenzhen Research Institute of Hunan University Shenzhen Guangdong 518055 P. R. China