1. Institute of Materials Research and Engineering (IMRE); Agency for Science, Technology and Research (A*STAR); 2 Fusionopolis Way, Innovis #08-03 Singapore 138634 Singapore
2. Energy Research Institute @NTU (ERI@N); Research Techno Plaza; X-Frontier Block, Level 5, 50 Nanyang Drive Singapore 637553 Singapore
3. Laboratory of Photonics and Interfaces; Ecole Polytechnique Fédérale de Lausanne (EPFL); Lausanne CH 1015 Switzerland
4. Department of Solar Energy and Environmental Physics; Jacob Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Sede Boqer Campus 84990 Israel
5. School of Materials Science and Engineering; Nanyang Technological University; 50 Nanyang Avenue Singapore 639798 Singapore