1. Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095, United States
2. Department of Materials Science and Engineering, University of California, Los Angeles, 410 Westwood Plaza, Los Angeles, California 90095, United States
3. Department of Physics and Astronomy, Georgia State University, 25 Park PI NE, Atlanta, Gerogia 30303, United States
4. Department of Materials Science and Nano Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
5. Department of Applied Physics and Materials Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, United States
6. National Center for Solar Energy Technology, Energy and Water Research Institute, King City for Science and Technology, Riyadh 114442, Saudi Arabia
7. College of Physics and Material Science, Henan Normal University, Xinxiang 453007, China