1. Anhui Provincial Key Laboratory of Photonic Devices and MaterialsAnhui Institute of Optics and Fine MechanicsChinese Academy of Sciences Hefei 230031 China
2. University of Science and Technology of China Hefei 230026 China
3. Key Laboratory of Photovoltaic and Energy Conservation MaterialsChinese Academy of Sciences Hefei 230031 China
4. School of Physics and Materials ScienceAnhui University Hefei 230601 China