1. Phosphors Research Laboratory, Department of Applied Chemistry, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan
2. Department of Chemical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
3. Department of Physics & Center for Solar Energy, Indian Institute of Technology Jodhpur, Karwar, Rajasthan 342037, India