  Piezoelectricity of organic polymers has attracted increasing interest
because of several advantages they exhibit over traditional inorganic ceramics.
While most organic piezoelectrics rely on the presence of intrinsic local
dipoles, a highly nonlocal electronic polarization can be foreseen in
conjugated polymers, characterised by delocalized and highly responsive
${\pi}$-electrons. These 1D systems represent a physical realization of a
Thouless pump, a mechanism of adiabatic charge transport of topological nature
which results, as shown in this work, in anomalously large dynamical effective
charges, inversely proportional to the band gap energy. A structural
(ferroelectric) phase transition further contributes to an enhancement of the
piezoelectric response reminiscent of that observed in piezoelectric
perovskites close to morphotropic phase boundaries. First-principles Density
Functional Theory (DFT) calculations performed in two representative conjugated
polymers using hybrid functionals, show that state-of-the-art organic
piezoelectric are outperformed by piezoelectric conjugated polymers, mostly
thanks to strongly anomalous effective charges of carbon, larger than 5e -
ordinary values being of the order of 1e - and reaching the giant value of 30e
for band gaps of the order of 1 eV.
