Dresden 2026 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 31: Transport in Materials: Diffusion, Charge, or Heat Conduction II
MM 31.4: Vortrag
Donnerstag, 12. März 2026, 11:00–11:15, SCH/A216
Understanding How Pressure Enhances Heat Transport in Organic Semiconductors — •Lukas Legenstein1,2, Sandro Wieser1,3, Michele Simoncelli4, and Egbert Zojer1 — 1Graz University of Technology, Austria — 2Montanuniversität Leoben, Austria — 3TU Vienna, Austria — 4Columbia University, USA
Understanding how lattice thermal conductivity changes under pressure is increasingly important in materials science, yet difficult to predict because materials exhibit a variety of behaviors, ranging from monotonic increases or decreases to anomalous trends. Molecular crystals, including organic semiconductors, stand out for exhibiting unusually large pressure-induced increases relative to their (ultra-)low thermal conductivities.
Our test system, naphthalene, crystallizes in a herringbone stack, a packing motif common in most π-conjugated organic semiconductors. Measurements up to 2 GPa from previous literature show an isotropic thermal conductivity that is up to four times higher than at ambient conditions. By combining highly accurate machine-learned potentials with the Wigner transport equation, we not only reproduce these findings but also elucidate how compression affects naphthalene's anisotropic thermal conductivity and how phonon tunneling becomes less relevant with increasing pressure. Finally, we trace the pressure-induced enhancement to frequency upshifts and the associated modifications in phonon scattering.
Keywords: thermal conductivity; phonons; simulations; machine-learned potentials; organic semiconductors