[1] ETH, Wood Mat Sci, Inst Bldg Mat, Stefano Franscini Pl 3, CH-8093 Zurich, Switzerland
[2] Empa Swiss Fed Labs Mat Sci & Technol, Appl Wood Mat, Uberlandstr 129, CH-8600 Dubendorf, Switzerland
[3] Empa Swiss Fed Labs Mat Sci & Technol, Lab Thin Films & Photovolta, Uberlandstr 129, CH-8600 Dubendorf, Switzerland