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MM: Fachverband Metall- und Materialphysik

MM 19: Poster Session

MM 19.36: Poster

Dienstag, 10. März 2026, 18:00–20:00, P5

Modelling heat transport in BTBT and its derivatives using non-equilibrium molecular dynamics (NEMD) simulations — •Simon Jamnik, Florian Lindner, Florian Unterkofler, and Egbert Zojer — Graz University of Technology

Benzothieno[3,2-b]benzothiophene (BTBT) is a high-performance organic semiconductor whose derivatives C8-BTBT (with an octyl side chain) and Ph-BTBT (with a phenyl side chain) are widely used in OFETs due to their high mobilities, environmental stability and solution processability. Side-chain engineering strongly influences their physicochemical and thermal properties: experiments show that alkyl chains improve solubility while suppressing heat transport, whereas phenyl chains enhance along-chain conductivity and reduce inter-chain transport.

To analyse these effects, we employ non-equilibrium molecular dynamics (NEMD), which provides a complementary real-space perspective through spatially resolved temperature profiles and enables the direct identification of thermal-transport bottlenecks. Accurate forces for large-scale NEMD were obtained using moment tensor potentials (MTPs) trained on ab initio data generated via VASPs on-the-fly machine-learning force-field (MLFF) framework, allowing near first-principles accuracy at greatly reduced computational cost.

Keywords: Machined-learned potentials; BTBT; NEMD; Thermal conductivity