We report the synthesis of a novel
pentacyclic donor moiety, dithienosilolothiophene,
and its incorporation into low bandgap semiconducting polymers. The
unique geometry of this new donor allowed attaching four solubilizing
side chains on the same side of the fused ring system, thus ensuring
sufficient solubility when incorporated into conjugated polymers while
simultaneously reducing the steric hindrance between adjacent polymer
chains. The optoelectronic properties of three new polymers comprising
the novel pentacyclic donor were investigated and compared to structurally
similar thieno[3,2-<i>b</i>]thienobis(silolothiophene) polymers.
Organic solar cells were fabricated in order to evaluate the new materials’
potential as donor polymers in bulk heterojunction solar cells and
gain further insight into how the single-sided side-chain arrangement
affects the active layer blend morphology
