1. Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia.
2. Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw, Poland.
3. Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA.
4. Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
5. Department of Electrical, Computer and Energy Engineering and Materials Science and Engineering Program, University of Colorado, Boulder, CO 80309, USA.
6. Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory, University of Colorado, Boulder, CO 80309, USA.