Dresden 2017 – wissenschaftliches Programm
CPP 55.1: Hauptvortrag
Donnerstag, 23. März 2017, 10:15–10:45, ZEU 222
Understanding charge transport in crystalline organic semiconductors — •Simone Fratini1, Sergio Ciuchi2, Alessandro Troisi3, and Didier Mayou1 — 1Institut Néel - CNRS and Université Grenoble Alpes, Grenoble, France — 2Department of Physical and Chemical Sciences, University of L’Aquila & CNR-ISC, L’Aquila, Italy — 3Department of Chemistry, University of Warwick, UK
Charge transport in crystalline organic semiconductors is intrinsically limited by the presence of large thermal molecular motions, which are a direct consequence of the weak van der Waals intermolecular interactions. These lead to an original regime of transport called transient localization, involving the quantum localization of the carriers at timescales shorter than the typical molecular motions. After a brief review of experimental observations that pose a challenge to textbook theories, I will present model calculations supporting the transient localization scenario. I will show that the theory consistently explains several common experimental features of organic semiconductors, such as the low mobilities falling below the Mott-Ioffe-Regel limit, the typical power-law temperature dependence observed in clean crystalline compounds as well as the observed non-Drude like behavior of the optical conductivity. I will then discuss efficient strategies to improve the mobility in this important class of materials and conclude with a systematic screening performed on the whole family of organic semiconductors, showing how the electronic structure determines their sensitivity to molecular disorder. Mobilities above 100 cm2/Vs are predicted to occur in appropriately tailored compounds.