1. Department
of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
2. Division of Physical Sciences and Engineering, Solar & Photovoltaics Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
3. School
of Physical Science and Technology, ShanghaiTech University, 100 Haike
Road, Shanghai 201210, China
4. Department
of Electrical and Computer Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States