EN
A series of new bis-(2-thienyl) maleimide monomers
have been synthesized and characterized. The bis-(2-
thienyl)maleimide unit has been copolymerized with different
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 effective 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 efficiencies of 35% exceeding those of the
corresponding binary blends.