Dresden 2017 – scientific programme

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DS: Fachverband Dünne Schichten

DS 23: Organic Semiconductors (jointly with CPP/HL)

DS 23.6: Talk

Tuesday, March 21, 2017, 10:45–11:00, POT 251

Crystalline Packing Motifs in Pentacene-like Organic Semiconductors — •Michael Klues and Gregor Witte — Fachbereich Physik, Universität Marburg, Germany

While the impact of chemical modifications on the molecular electronic system can be well computed, the influence on solid state properties is hardly predictable. In fact already slight chemical modifications, like the introduction of heteroatoms or small side groups, often lead to dramatically changed crystal structures and thereby rather different charge carrier mobilities or exciton binding energies. Within a comparative study of various pentacene-like organic semiconductors, based on a Hirshfeld analysis [1] we reveal correlations between molecular properties and packing motives. By choosing molecules with nearly identical geometrical dimensions the complexity of intermolecular interactions is considerably reduced and effects of electrostatic potentials, hydrogen bonds and atom sizes can be carved out. Thereby, we attain a simple rule for predicting the occurrence of herringbone packing motifs and point out the relevance of hydrogen bonds for parallel molecular arrangements as found previously for partially fluorinated HBC. [2] Furthermore we suggest a route to increase intermolecular orbital overlap by integration of large heteroatoms in the periphery of aromatic systems which yields an improved charge carrier mobility in the case of DNTT.

[1] M.A Spackman; D. Jayatilaka, CrystEngComm, 11, 19, (2009)

[2] T. Breuer et al., Phys. Chem. Chem. Phys., (2016), DOI: 10.1039/C6CP06126E