1. Department of Electronic and Computer Engineering; The Hong Kong University of Science and Technology; Clear Water Bay Kowloon Hong Kong SAR China
2. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology; MA 02139 USA
3. Department of Materials Science and Engineering; Shenzhen Key Laboratory of Full Spectral Solar Electricity Generation (FSSEG); Southern University of Science and Technology; No. 1088, Xueyuan Rd Shenzhen Guangdong 518055 China