Heteroaromatic-based organic and organometallic dyes for dye-sensitized solar cells

Solar energy is the most abundant clean and renewable energy source but photovoltaic technology has not yet found widespread use due to its high intrinsic costs. Emerging thin-film molecular-based photovoltaic technologies, based on organic and organometallic molecules and polymers, offer a unique promise of cheap, efficient, and robust devices. Amongst the new technologies, dye-sensitized solar cells (DSCs) show one of the best potential of high-conversion efficiency and low-cost manufacturing. Here we present our recent studies on DSC based on organic and organometallic photosensitizers. The organic sensitizers have an unprecedented multi-branched structure, at variance with the conventional uni-dimensional geometry, for enhanced power conversion efficiencies and stabilities. We also report our most recent studies on a new family of cyclometalated complexes for efficient and more stable devices. In both cases the design of the sensitizer dyes originated from a careful selection of electron-rich and electron-poor aromatic and heteroaromatic fragments in order to tune, and optimize, optical and energetic properties and, in turn, device performance. The new dyes have been completely characterized in their optical and electrochemical properties and investigated in photovoltaic devices. [1] [1] A. Abbotto, F. Sauvage, C. Barolo, F. De Angelis, S. Fantacci, M. Graetzel, N. Manfredi, C. Marinzi, M. K. Nazeeruddin, Dalton Trans. 2011, 40, 234-242; A. Abbotto, N. Manfredi, C. Marinzi, F. D. Angelis, E. Mosconi, J. -H. Yum, Z. Xianxi, M. K. Nazeeruddin, M. Gratzel, Energy Environ. Sci. 2009, 2, 1094-1101; A. Abbotto, C. Barolo, L. Bellotto, F. D. Angelis, M. Gratzel, N. Manfredi, C. Marinzi, S. Fantacci, J. -H. Yum, M. K. Nazeeruddin, Chem. Commun. 2008, 42, 5318-5320.