The use of combinatorial materials development for polymer solar cells

Vile use a combinatorial approach to develop molecular plastic solar cells based on soluble fullerene derivatives blended with conjugated polymers. A combinatorial way of sample preparation is well suited to deal with the mul titude of possible combinations of the components of such blends. We use hi gh mobility poly(thiophene) and poly(phenylenevinylene) derivatives to be c ombined with accepters, Gradients of methanofullerene/polymer concentration were formed by diusion of the low molecular weight component in the spin-c ast polymer matrix, Likewise the gradients of zinc phthalocyanine/C-60 were prepared by co-evaporation of the two materials from two sources to make a linear array of photodiode devices, Photo- and electrophysical properties, such as absorption, luminescence, short circuit photocurrent and open circ uit photovoltage, were measured using a specially designed installation wit h a resolution of 70-100 mu. Clear evidence was obtained that the photoconv ersion efficiency increased with the amount of methanofullerene up to very high levels, in the case of methanofullerene/polymer blends, verifying the important role of the acceptor in the photoconversion. By choosing the opti mal ratio between C-60 and ZnPc in the evaporated layer it Is possible to o btain high photocurrent in the 600-700 nm range, due to the added contribut ion from photoinduced electron transfer between the two molecules, Copyrigh t (C) 2000 John Wiley & Sons, Ltd.