Copper(I) complexes and their application dye sensitized solar cells

The easy prevision that in the near future the price of the energy derived from fossil fuels could be significantly increased and the well note limits in the applications of silicon-based photovoltaic (PV), get to the conclusion that the development of new, efficient and low-cost PV technologies will be more and more required. Up to day dye sensitized solar cells (DSSCs) represent one of the more attractive technological alternative to silicon-based PV. In this context, the best efficiency for the conversion of solar energy has been realized using a large number of Ru(II) polypyridyl complexes [1], however very good results were also obtained in the presence of metal-free organic dyes [2]. Recently also Cu(I) complexes have been proposed as effective sensitizers in DSSCs [3] even if their efficiency is much lower than that obtained with Ru-based devices, nevertheless copper still remains very interesting in this application because it can offer a considerable opportunity for reduction in cost. Here we report the synthesis of suitable substituted 2,2’-dipyridil (Scheme 1) together with the corresponding bis-dipy Cu(I) complex. Scheme 1 Several DSSCs devices have been prepared employing Cu(I) complexes with different protonation degree of the ligand 1, and the results have been discussed as a function of the variation of the electrolyte. [1] a) M. K. Nazeeruddin, A. Kay, I. Rodicio, R. Humpry-Baker, E. Mueller, P. Liska, N. Vlachopoulos and M. Grätzel, J. Am. Chem. Soc., 115, 1993, 6382; b) P. Wang, S. M. Zakeeruddin, I. Exnar and , M. Grätzel, Chem. Commun., 2003, 1456; c) A. Abbotto, C. Barolo, L. Bellotto, F. De Angelis, M. Grätzel, N. Manfredi, C. Marinzi, S. Fantacci, J. –H. Yum and M. K. Nazeeruddin, Chem. Commun., 2008, 5318. [2] A. Mishra, M. K. R. Fisher and P. Bäuerle, Angew. Chem. Int. Ed., 48, 2009, 2474. [3] a) N. Alonse-Vante, J. –F. Nierengarten and J. –P. Sauvage, J. Chem. Soc., Dalton Trans., 1996, 1649; b) S. Sakaki, T. Kuroki and T. Hamada, J. Chem. Soc., Dalton Trans., 2002, 840; c) N. Robertson, ChemSusChem 1, 2008, 977; d) E. C. Constable, A. Hernadez Redondo, C. E. Housecroft, M. Neuburger and S. Schaffner, Dalton Trans., 2009, 6634.