Functional Π-conjugated polymers based on maleimide for photovoltaic applications

Abstract

A series of new bis-(2-thienyl) maleimide monomers have been synthesized and characterized. The bis-(2thienyl)maleimide unit has been copolymerized with dierent aromatic comonomers. Stille coupling polymerizations under various conditions have been utilized. The copolymers were then characterized by size-exclusion chromatography and their optical and electronic properties were investigated by UV-Vis absorption spectroscopy and cyclic voltammetry. All maleimide based copolymers shared similar LUMO energy levels, which are largely determined by the acceptor moiety, and are close to that of PC61BM to be eective for charge dissociation. These low band gap polymers have been tested for photovoltaic applications and have shown moderate photovoltaic performance. Interesting results were obtained by adding the polymer to the P3HT:PC61BM mixture, as a third component. The ternary blend BHJ solar cells showed power conversion eciencies of 35% exceeding those of the corresponding binary blends.