1. Department
of Materials Science and Engineering and Centre for Functional Photonics
(CFP), City University of Hong Kong, Kowloon, Hong Kong SAR
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