1. Department of Solar Energy and Environmental Physics; Jacob Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Sede Boqer Campus 8499000 Israel
2. Ilse Katz Institute for Nanoscale Science and Technology; Ben-Gurion University of the Negev; Be'er Sheva 8410501 Israel
3. Department of Materials and Interfaces; Weizmann Institute of Science; Rehovot 76100 Israel