[1] ASTAR, Inst Mat Res & Engn, 2 Fusionopolis Way,Innovis 08-03, Singapore 138634, Singapore
[2] Energy Res Inst NTU ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore
[3] Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland
[4] Ben Gurion Univ Negev, Jacob Blaustein Inst Desert Res, Dept Solar Energy & Environm Phys, Sede Boqer Campus, IL-84990 Sede Boqer, Israel
[5] Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore