  Precise determination of the solid-state microstructure of semiconducting
polymers is of paramount importance for the further development of these
materials in various organic electronic technologies. Yet, prior
characterization of the ordering of semiconducting polymers often resulted in
conundrums in which X-ray scattering and microscopy yielded seemingly
contradicting results. Here, based on fast scanning calorimetry, we introduce
for the first time the concept of the semi-para-crystallinity and measurement
of the degree of para-crystallinity (ordered volume/mass fraction) in a set of
materials that previously eluded understanding. In combination with lattice
distortion determination within para-crystals (g-parameter from X-ray
scattering) and nanomorphology, the complete solid-state microstructure is
correlated with device properties. Our data show that the long-range charge
carrier transport in these materials is more sensitive to the interconnection
of para-crystal units than to the amount of structural order itself.
