1. Department of Materials Science, National Engineering Laboratory for TFT-LCD Materials and Technologies, Fudan University, Shanghai 200433, China
2. Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
3. Department of Photonics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
4. Department of Material and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan