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Precise control of orientation and crystallinity is achieved in regioregular poly(3-hexylthiophene) (P3HT) thin films by using high-temperature rubbing, a fast and effective alignment method. Rubbing P3HT films at temperatures TR ≥ 144 °C generates highly oriented crystalline films with a periodic lamellar morphology with a dichroic ratio reaching 25. The crystallinity and the average crystal size along the chain axis direction, lc, are determined by high-resolution transmission electron microscopy and differential scanning calorimetry. The inverse of the lamellar period l scales with the supercooling and can accordingly be controlled by the rubbing temperature TR. Uniquely, the observed exciton coupling in P3HT crystals is correlated to the length of the average planarized chain segments lc in the crystals. The high alignment and crystallinity observed for TR > 200 °C cannot translate to high hole mobilities parallel to the rubbing because of the adverse effect of amorphous zones interrupting charge transport between crystalline lamellae. Although tie chains bridge successive P3HT crystals through amorphous zones, their twisted conformation restrains interlamellar charge transport. The evolution of charge transport anisotropy is correlated to the evolution of the dominant contact plane from mainly face-on ( TR ≤ 100 °C) to edge-on ( TR ≥ 170 °C). [ABSTRACT FROM AUTHOR]

In this article we highlight the importance of film deposition conditions on the electrochemical behaviour of the work horse of the organic electronics community, namely poly(3-hexylthiophene) (P3HT). While a huge number of publications have dealt with the influence of morphology on optical, electronic and opto-electronic properties, the effect on the electrochemical response has been less addressed. Electrochemistry is often only used as convenient tool in this community to determine the energy levels or more specifically the HOMO level of P3HT. This is performed by measuring oxidation onset potentials and introducing correction factors which relate the electrochemical with the Fermi scale. Here we want to stress out that this procedure should be performed with great care in order to get meaningful data. We demonstrate that film deposition conditions can strongly alter the oxidation behaviour of the polymers which makes the determination of the oxidation onset potentials and energy levels very difficult. We compare state-of-the-art of electropolymerisation and solution deposition of chemically synthesized polymers of defined regioregularity with our own expertise on deposition and controlling crystallisation in films. [ABSTRACT FROM AUTHOR]