1. Department of Electronic Engineering, CHOSE-Centre for Hybrid and Organic Solar Energy, University of Rome Tor Vergata, via del Politecnico 1, 00133 Rome, Italy
2. Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, 97187 LuleÅ, Sweden
3. NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75080, United States
4. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy