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In this work, in situ studies of organic thin films under stretching are developed. A high efficiency PffBT4T-2OD π-conjugated polymer (PCE11) was coated directly on a stretchable substrate in order to examine the impact of tensile strain on the structural properties. For that purpose, in situ grazing incidence x-ray diffraction coupled with optical microscopic observations have been carried out to measure the structural parameters of PCE11 and to probe the mechanical behavior of polymer chains under uniaxial tensile load. It is observed that in the range between 0% and 15%–20% of stretching, the polymer chains become more oriented. Meanwhile, an increase in negative values of deformation, i.e., compression of the polymer chains along the film normal was measured. Beyond this range of stretching, the polymer order declined and the stress was relaxed. This relaxation is explained by the increased number of cracks spreading over the entire film as observed using optical microscopy. [ABSTRACT FROM AUTHOR]

Organic materials and blends have received a great deal of interests for application in large area, flexible, and low-cost organic/hybrid electronics. In this work the optical, structural and the electrical behaviors of a new active layer system composed by functionalized gold nanoparticles (AuNPs) and conjugated polymers, were investigated. For this purpose, gold nanoparticles with diameter of about 5 nm were chosen, coated with the bifunctional π-conjugated ligand (9,9-didodecyl-2,7-bis(acetylthio)fluorene, FL) for their high stability and easy dispersibility in organic solvents. The blends based on AuNPs and regioregular poly-3-hexylthiophene (P3HT) were prepared by adding an increasing percentage by weight of nanoparticles, i.e. from 10% to 90 wt%, in the P3HT polymeric matrix. The presence of nanoparticles was confirmed by UV-Vis spectroscopy, electron microscopy and X-ray diffraction techniques. The optical characterization of the composites demonstrated the possibility to tune the optical behavior of the P3HT by adding increasing percentages of AuNPs into the polymer matrix. Their inclusion results in a loss of P3HT crystallinity and in a simultaneous increase of the π-π interaction between the polythiophene chain and fluorene ligand. To better investigate the films, Grazing Incident X-ray Diffraction (GIXD) measurements were carried out and the blend containing 30 wt% of AuNPs in P3HT reveals an optimal condition, combining good structural order and interconnectivity in the polymer matrix. The electrical characterization of the AuNPs/P3HT blends reveals an improvement of the electrical conductivity in all the prepared blends, that show higher conductivity values compared to the pristine AuNPs and P3HT materials. The best performance is achieved adding 30 wt% of AuNPs to P3HT resulting in an enhancement of conductivity by about 350% compared to that of the pure polymer. This result could be of great interest for the realization of new conductive film composites to use in opto-electronic devices. [Display omitted] • Gold nanoparticles (AuNPs) and regioregular poly-3-hexylthiophene (P3HT) were blended in different weight percentages. • Tuning of the structural and optical features by increasing percentages of AuNPs into the P3HT matrix. • The electrical characterization of the AuNPs/P3HT blends reveals a substantial improvement of the conductivity. • The best performance is achieved adding 30%wt of AuNPs to P3HT with 350% enhancement of conductivity compared to pure P3HT. [ABSTRACT FROM AUTHOR]