1. Hybrid Solar Cells, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, Tampere FI-33014, Finland
2. Department of Chemical Sciences, University of Naples Federico II, Comp. Univ. Monte Sant’Angelo, Naples 80126, Italy
3. Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (DICATECh), Politecnico di Bari, Via Orabona 4, Bari 70125, Italy
4. Surface Science Group, Photonics Laboratory, Tampere University, P.O. Box 692, Tampere FI-33014, Finland
5. Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 692, Tampere FI-33014, Finland
6. CNR NANOTEC─Istituto di Nanotecnologia, Via Monteroni, Lecce 73100, Italy
7. Department of Physics “Ettore Pancini”, University of Naples Federico II, Comp. Univ. Monte Sant’Angelo, Naples 80126, Italy