SKM 2021 – wissenschaftliches Programm
CPP 10: Organic Electronics and Photovoltaics, Electrical and Optical Properties (joint session CPP/KFM)
CPP 10.2: Vortrag
Donnerstag, 30. September 2021, 14:00–14:15, H3
On the role of interfaces in controlling the molecular orientation in thin films of polythiophenes — •Oleksandr Dolynchuk1, Philip Schmode2, Matthias Fischer1, Mukundan Thelakkat2, and Thomas Thurn-Albrecht1 — 1Experimental Polymer Physics, Martin Luther University Halle-Wittenberg, Germany — 2Applied Functional Polymers, University of Bayreuth, Germany
Directed crystallization on a substrate is a superior method for inducing crystal orientation in many ordered materials. Although a preferred face-one molecular orientation was evidenced in monolayers of poly(3-hexylthiophene) (P3HT) on graphite, a full face-one orientation in thicker P3HT films has not been realized so far. By using surface-sensitive GIWAXS, here we show that thin films of P3HT crystallized on graphene exhibit a double-layered face-on and edge-on crystal orientation with the latter formed on the top surface . We assume that it is a result of two competing interfacial orientations initiated at the interfaces to graphene and vacuum. By increasing the side-chain polarity in poly[3-(6-bromohexyl)]thiophene, the influence of the interface to vacuum can be reduced, resulting in full face-on orientation in films with a thickness of up to 26 nm . Our findings evidence that directed crystallization can be used to control the orientation of semicrystalline conjugated polymers in thin films if interactions with both interfaces are properly taken into account.
 Dolynchuk et al. Macromolecules 2021, 54, 5429-5439.