1. Division of Physical Sciences and Engineering; Solar and Photovoltaic Engineering Center; King Abdullah University of Science and Technology (KAUST); Thuwal 23955-6900 Saudi Arabia
2. Department of Electrical and Computer Engineering; University of Toronto; Toronto Ontario M5S 3G4 Canada
3. Department of Physics and Astronomy, Jorgensen Hall, 855 North 16th Street; University of Nebraska-Lincoln; Lincoln NE 68588-0299 USA
4. Canadian Light Source; Saskatoon SK S7N 2V3 Canada