Regensburg 2022 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 40: Organic Electronics and Photovoltaics 3

CPP 40.5: Talk

Thursday, September 8, 2022, 16:15–16:30, H38

Understanding Phonon Properties and the Thermal Conductivity of Crystalline Polymers — •Lukas Reicht, Lukas Legenstein, Tomas Kamencek, Sandro Wieser, and Egbert Zojer — Graz University of Technology, Austria

Disordered polymers are characterized by a very low thermal conductivity on the order of 0.1 W/mK. In contrast, recent studies have shown that aligned (crystalline) polymers can have thermal conductivities comparable to those of metals. Given these prospects, it is interesting to understand, how the thermal conductivity of a polymer depends on its chemical structure. A crucial step in that context is to investigate phonons and their influence on thermal transport. For simulating the phonons, we relied on density-functional theory (DFT) calculations combining phonopy and the Vienna Ab initio Simulation Package (VASP). In a second step, anharmonic force constants and thermal conductivities were calculated with phono3py and hiPhive. Additionally, we explored the capabilities of on-the-fly machine learned force fields (ML-FF), trained on DFT data, as implemented in VASP. These approaches were tested and benchmarked for polyethylene as a comparably simple model system. The final goal of our work is to then apply the above methodology to other polymers, systematically varying the structure of the backbone, thereby finding structure-to-property relations. These polymers include poly(p-phenylene), polythiophene, polyfuran, polyselenophene, poly(3-hexylthiophen-2,5-diyl) (P3HT) and Poly(p-phenylene vinylene) (PPV).