Berlin 2018 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Organic Electronics and Photovoltaics - Layer Morphology and Molecular Aggregation

CPP 3.5: Talk

Monday, March 12, 2018, 10:45–11:00, C 243

Effect of Side Chain Modification on Crystallization and Crystal Orientation in Thin Films of Poly(3-(6-bromohexyl)-thiophene) — •Oleksandr Dolynchuk¹, Philip Schmode², Paul M. Reichstein², Matthias Fischer¹, Mukundan Thelakkat², and Thomas Thurn-Albrecht¹ — ¹Experimental Polymer Physics, Institute of Physics, Martin Luther University Halle-Wittenberg, Germany — ²Applied Functional Polymers, Macromolecular Chemistry I, University of Bayreuth, Germany

Semicrystalline conjugated polymers are of great interest as organic materials for various electronic devices due to a remarkable combination of semiconducting, thermal and mechanical properties, which strongly depend on morphology and orientation of polymer crystals. This work aims a comparative study of crystallization of poly(3-(6-bromohexyl)-thiophene) (P3BrHT) and poly(3-hexylthiophene) (P3HT) in bulk and in thin films. Differential scanning calorimetry evidenced a significant decrease of crystallization and melting temperatures and melting enthalpy of P3BrHT as compared to P3HT. Temperature dependent wide-angle XRD revealed a distortion of crystal lattice in bulk P3BrHT and allowed estimating crystallinity in this material that amounted to about 43%. The crystal orientation in ultrathin films of both polymers spin coated on SiO₂/Si and graphene was explored using grazing incidence XRD. The results indicated stronger face-on crystal orientation with π-π stacking normal to both substrates in as-spun P3BrHT than P3HT, whereas melt-crystallized P3BrHT on graphene has only face-on oriented crystals.