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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster II

CPP 21.13: Poster

Tuesday, March 19, 2024, 18:00–20:00, Poster E

Influence of Cooling Rate and Molecular Weight on Crystallization of Thin Films of Poly-(3-hexylthiophene) at the Vacuum Interface — •Alexander J. Much and Oleksandr Dolynchuk — Experimental Polymer Physics, Institute of Physics, Martin-Luther-University Halle-Wittenberg, Germany

The electronic properties of organic semiconductors in general and of semiconducting polymers in particular depend on the crystal orientation. It was previously shown that the interface to air or vacuum induces edge-on orientation in the model semiconducting polymer poly-(3-hexylthiophene) (P3HT) during crystallization from the melt. To better understand the kinetics of this crystallization phenomenon, here we investigate the effect of cooling rate on the crystal orientation formed in P3HT films on glass substrates. Furthermore, since molecular weight Mw is known to affect the crystallinity and degree of order in bulk P3HT, we also investigate whether Mw has any effect on the crystal orientation of P3HT films. Using Grazing Incidence Wide Angle X-ray Scattering, we show that there is little difference in crystal orientation in films of P3HT with Mw=15kg/mol and Mw=47kg/mol after crystallization during slow cooling. However, an increased cooling rate during crystallization from the melt impairs the formation of edge-on crystals at the vacuum interface in high Mw P3HT, while the effect is nontrivial for low Mw P3HT. Thus, our results demonstrate that the kinetics of P3HT crystallization at the vacuum interface is dependent on thr Mw of P3HT.

Keywords: P3HT; Interface-Induced Crystallization; Polymer Crystallization; Semiconducting Polymers