1. Karlsruhe Institute of Technology (KIT), Institutfür Anorganische Chemie, Engesserstraße 15, D-76131 Karlsruhe, Germany
2. Department of Optoelectronic Engineering, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Road, Shoufeng, Hualien, 97401 Taiwan