Résumé:
We describe the impact of tensile strains on the structural properties of thin films
composed of PffBT4T-2OD π-conjugated polymer and PC71BM fullerenes coated on a stretchable
substrate, based on a novel approach using in situ studies of flexible organic thin films. In situ
grazing incidence X-ray diffraction (GIXD) measurements were carried out to probe the ordering of
polymers and to measure the strain of the polymer chains under uniaxial tensile tests. A maximum
10% tensile stretching was applied (i.e., beyond the relaxation threshold). Interestingly we found
different behaviors upon stretching the polymer: fullerene blends with the modified polymer;
fullerene blends with the 1,8-Diiodooctane (DIO) additive. Overall, the strain in the system was
almost twice as low in the presence of additive. The inclusion of additive was found to help in
stabilizing the system and, in particular, the π–π packing of the donor polymer chains.
