posted on 2022-02-03, 02:13authored byRishat Dilmurat, Vincent Lemaur, Yoann Olivier, Sai Manoj Gali, David Beljonne
The
design of semiconducting polymers with optimal charge transport
characteristics has been at the crux of scientific research during
the recent decades. While increase in crystalline order and planar
conjugated backbones were demonstrated to be the key to success, they
are not always mandatory. Sometimes, the charge carrier mobility can
be enhanced by selecting conjugated backbones that are resilient to
thermal fluctuations, despite leading to poor structural order. Herein,
by coupling all-atom molecular dynamics simulations, electronic structure
calculations, and kinetic Monte Carlo charge transport simulations,
we demonstrate that the charge carrier mobility in amorphous donor–acceptor
conjugated polymers is controlled by the density and quality of close-contact
points between the chains and that the latter varies with the size
of the donor block and the resulting alkyl side-chain density. We
show an application of this strategy to the high-mobility poly(indacenodithiophene-alt-benzothiadiazole) (IDTBT) and poly(dithiopheneindenofluorene-alt-benzothiadiazole) (TIFBT) copolymers.