Bithiophene-based polybenzofulvene derivatives with high stacking and hole mobility

Four new benzofulvene derivatives bearing bithiophene chromophores at two different key positions of the phenylindene scaffold were prepared in order to evaluate the role of different chromophores in the optoelectronic features of polybenzofulvene derivatives. The results of the photophysical studies showed that the optical properties of the newly-synthesized bithiophene-functionalized polymers were affected by both the polymer enchainment and the substitution topology of the monomeric units. On the other hand, the hole-mobility appeared to be affected to a lesser extent, but the best performances were obtained in poly-6-HBT-BF3k showing the strongest bithiophene side chain packing. This work demonstrates that the optoelectronic properties of polybenzofulvene derivatives can be optimized by a targeted chemical design such as side chain engineering.