Lattice thermal conductivity of CsSnBr3/Cs2SnBr6 interface from ab initio based neuroevolution potential simulations

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Engineering interface phonons is critical for developing materials with extremely low thermal conductivity.
• Such materials are essential components for efficient energy conversion devices.

Purpose of the Study:

• To report ultralow lattice thermal conductivity at the CsSnBr3/Cs2SnBr6 interface.
• To investigate the mechanisms behind this low thermal transport.

Main Methods:

• Large-scale atomic molecular dynamics (MD) simulations.
• Ab initio density functional theory (DFT) calculations to derive accurate neuroevolution potentials.
• Analysis of phonon scattering, localization, and anharmonicity.

Main Results:

• Achieved an ultralow lattice thermal conductivity of 0.173 W m−1 K−1 at the CsSnBr3/Cs2SnBr6 interface.
• Observed enhanced anharmonicity and significant phonon scattering/localization.
• Identified a strong mixed phonon liquid character and nonlinear interface density-dependent thermal conductivity.

Conclusions:

• The CsSnBr3/Cs2SnBr6 interface exhibits exceptional phononic properties for thermal management.
• Findings provide insights for designing crystalline anisotropic thermoelectric materials.
• Phonon engineering at interfaces is a viable strategy for advanced thermoelectric applications.