Perylene-oligothiophene-perylene triads for photovoltaic applications

A series of novel acceptor-donor-acceptor triad systems, consisting of head-to-tail-coupled oligo(3-hexylthiophene)s integrated between two terminal perylenemonoimides are described. These hybrid molecules, which differ by the length of the oligothiophene units from a quaterthiophene up to a dodecithiophene were synthesized by an effective palladium-catalyzed Ullmann-type homo-coupling reaction in good yields. The optical and electrochemical properties of these compounds were determined, and on the basis of this series structure-property relationships have been established which provide vital information for the fabrication of the corresponding photovoltaic devices. Because the synthesized perylenyl-oligothiophenes distinguish themselves by a high absorption between 300 and 550 nm and an almost complete fluorescence quenching of the perylene acceptor, they meet the requirements for organic solar cells. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).