Acknowledgements
This research was supported by “EFOR” Project (Energia da FOnti Rinnovabili, Iniziativa CNR per il Mezzogiorno L. 191/2009 art. 2 comma 44) and by “SAGRO” Project financed by Regione Siciliana (Assessorato Regionale Attività Produttive progetti PO FESR 2007/2013 linea d’intervento 4.1.1.1). Furthermore, we acknowledged Programma Operativo Nazionale Ricerca e Competitività 2007–2013 – projects FOTORIDUCO2 (PON 01_02257). We gratefully acknowledge Giuseppe Spinella, Roberto Caruso and Giuseppe Lupò, technicians of Mechanical and electronic lab at IPCF-CNR, for the technical assistance and for the fabrication of accessories and components useful for some electrical characterizations and measurements.