1. Dept. of Chemical and Geological Sciences Università degli Studi di Cagliari 09042 Monserrato, Cagliari Italy
2. Organic Semiconductor Centre EaStCHEM School of Chemistry University of St Andrews Fife KY16 9ST UK
3. Department of Physics Università degli Studi di Cagliari 09042 Monserrato, Cagliari Italy
4. Department of Mechanical Chemical and Materials Engineering Università degli Studi di Cagliari via Marengo 2 09123 Cagliari Italy
5. Department of Biomedical Sciences Università degli Studi di Cagliari 09042 Monserrato, Cagliari Italy