Organic solar cells based on an interpenetrated network of conjugated polymer as donor and fullerene derivative as acceptor materials have a great potential for improving efficiency. We fabricated a device based on a composite of poly(2-methoxy-5-(2′-ethylhexyloxy)-1, 4-phenylenevinylene and [6,6]-phenyl C60 butyric acid methyl ester. Surface treatment, insertion of interfacial layers, and improvement of the morphology of the active layer significantly increase the photovoltaic performances of the structure. We obtain an open circuit voltage of 0.87 V and short circuit current density of 8.4 mA/cm2 under 100 mW/cm2 air-mass 1.5 solar simulator illumination, yielding a 2.9% power conversion efficiency.

Our recent works on fused TTF-C 60 dyads, (TTF) n -C 60 polyads and C 60 -TTF-C 60 dumbbell triads in which the acceptor C 60 is doubly tethered to the donor tetrathiafulvalene through a rigidified cyclohexene ring are presented. This approach was developed in order to control the relative orientation as well as the distance between both donor and acceptor entities. Thereby, through-space interactions which are of great importance for photoinduced electron-and/or energy-transfer processes are expected to dominate because of the special topology of the molecules. The two linked C 60 and TTF chromophores in such adducts are not only in close proximity but also have optimal orbital orientations, thus facilitating these through-space electronic interactions. These new C 60 -based assemblies were synthesized by [4 1 2] Diels-Alder cycloaddition reactions. The different methodologies considered for their synthesis are discussed, their analytical, spectroscopic characterizations and electrochemical properties are also described. The selective electro-oxidation or reduction afforded the corresponding radical cation and radical anion which were characterized by EPR. These C 60 -based assemblies were studied for their nonlinear optical and optical limiting applications. Moreover, intramolecular photoinduced charge-separation and charge-recombination processes in a fused C 60 -TTF-C 60 dumbbell triad which was designed to be soluble in organic solvents were investigated by time-resolved absorption and fluorescence techniques. Appreciable interaction between the C 60 moiety and TTF moiety in the ground state was suggested by steady-state absorption spectra and the fluorescence spectra showed considerable interaction in the singlet excited state. The nanosecond transient absorption spectra displayed the formation of the chargeseparated radical pair C 60 -TTF ? 1 -C 60 ? 2 , characterized by a lifetime of ca. 20 ns in benzonitrile.

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