Machine-learning-boosted ab-initio study of the thermal conductivity of Janus PtSTe van der Waals heterostructures - Efficient NNFF + phonon BTE/MD

Aug 5, 2026

Exploring thermal transport in PtSTe-based van der Waals heterostructures, this study introduces an efficient neural-network force field (NNFF) to enable predictive, first-principles-informed calculations. Thermal conductivity is evaluated using both the phonon Boltzmann transport equation and equilibrium molecular dynamics (MD) simulations. Predictions agree with theoretical and experimental trends and show that heterogeneous combinations such as PtSTe–PtTe2 significantly reduce room-temperature thermal conductivity, attributed to broken out-of-plane symmetries and weak van der Waals interactions. The work also demonstrates that NNFF-based MD captures higher-order anharmonic phonon properties more effectively.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Introduction

Thermoelectric motivation and low-κ materials

Janus TMDCs and symmetry breaking

van der Waals heterostructures and stacking effects

Computational challenge and NNFF-based solution approaches

Machine-learning-boosted ab-initio study of the thermal conductivity of Janus PtSTe van der Waals heterostructures Lijun Pan, 1, 2 Jes´us Carrete,3, 2, ∗ Zhao Wang, 1 and Georg K. H. Madsen2 1 Department of Physics, Guangxi University, Nanning 530004, China 2 Institute of Materials Chemistry, TU Wien, 1060 Vienna, Austria 3 Instituto de Nanociencia y Materiales de Arag´on (INMA), CSIC-Universidad de Zaragoza, E-50009 Zaragoza, Spain Calculating the thermal conductivity of heterostructures with multiple layers presents a significant challenge for state-of-the-art ab-initio methods. In this study we introduce an efficient neuralnetwork force field (NNFF) to explore the thermal transport characteristics of van der Waals heterostructures based on PtSTe, using both the phonon Boltzmann transport equation and molecular dynamics (MD) simulations. Besides demonstrating a remarkable level of agreement with both theoretical and experimental data, our predictions reveal that heterogeneous combinations like PtSTePtTe2 display a notable reduction in thermal conductivity at room temperature, primarily due to broken out-of-plane symmetries and the presence of weak van der Waals interactions. Furthermore, our study highlights the superiority of MD simulations with NNFFs in capturing higher-order anharmonic phonon properties. This is demonstrated through the analysis of the temperature-dependent thermal conductivity curves of PtSTe-based van der Waals heterostructures, and advances our understanding of phonon transport in those materials. I. INTRODUCTION Finding materials with a low thermal conductivity (κ) is a necessary step to create thermoelectric (TE) devices able to efficiently scavenge electrical power from waste heat. In this context, monolayer transition metal dichalcogenides (TMDC) have emerged as promising candidates [1] since they also exhibit large charge-carrier effective masses. Both factors contribute to raising the dimensionless thermoelectric figure of merit (zT), the key descriptor of thermoelectric performance. A particularly interesting variation on those basic monolayer structures are Janus TMDCs with the formula MXY (where M is a transition metal and X and Y represent two different chalcogens) and a broken reflection symmetry in the outof-plane direction. A number of experimental and theoretical studies have looked into the prospects of 2D Janus TMDC monolayers as TE materials and their connections with symmetry [2–9] . For instance, the Janus monolayer MoSSe has been experimentally synthesized [8] and found to have a thermal conductivity significantly lower than that of MoS2 and only slightly higher than that of MoSe2 despite the much heavier average atomic mass of the chalcogens in the latter [6] . Furthermore, monolayer PtSTe shows a lower thermal conductivity than both of its parent structures (PtTe2 and PtS2 ) [9] . A large set of additional degrees of freedom for tuning TE performance comes from the possibility of stacking those monolayers, as the transport properties of weakly bound layered structures are strongly dependent on their thickness and stacking sequence. For instance, the κ of bilayer graphene is much lower than that of monolayer graphene [10], a change driven by new phonon scattering ∗ [jcarrete@unizar.es](jcarrete@unizar.es) channels caused by the weak interlayer coupling. More generally, van der Waals Heterostructures (vdWHSs) of 2D layered materials can display emerging functionalities distinct from those of the individual components. The zT of WS2 /WTe2 bilayers has been theoretically predicted to reach the high value of 2 .4 at room temperature due to its ultralow thermal conductivity [11] . This creates a strong motivation to design and test novel heterostructures, and 2D monolayer Janus TMDCs standout as promising building blocks for those. In this work, we focus on the thermal conductivity of different bi- and trilayer vdWHSs composed of PtS2 , PtTe2 , and Janus PtSTe

FAQs

Why are low thermal conductivity materials important for thermoelectric devices?

Low thermal conductivity helps improve thermoelectric efficiency by enabling efficient conversion of waste heat to electrical power in thermoelectric devices.

What role does broken out-of-plane symmetry play in Janus TMDCs like PtSTe?

Janus TMDCs exhibit broken reflection symmetry in the out-of-plane direction, which influences phonon transport and contributes to altered thermal conductivity behavior.

How do phonon BTE and molecular dynamics (MD) approaches differ in this study?

The study computes thermal conductivity using both phonon Boltzmann transport equation and equilibrium MD with the same NNFF, with MD shown to better capture higher-order anharmonic phonon properties.

Aug 5, 2026

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