1. Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, Nicosia 1678, Cyprus
2. Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
3. Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
4. Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 4DE, United Kingdom
5. Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY, United Kingdom