We study the anharmonic phonon interactions in the single-crystal semiconducting (α) and metal-like (β) van der Waals In2Se3 layers, through the determination and analysis of temperature-dependent Raman spectra and thermal conductivities, supported by first-principles calculations of phonon band structures. Our results indicate strong lattice anharmonicity in β-In2Se3 giving rise to significant phonon peak broadening and a suppressed lattice thermal conductivity and reveal that the anharmonic phonon interactions are the main thermal transport-limiting mechanism in both phases. The low thermal conductivity combined with a large electrical conductivity makes the metal-like β-In2Se3 a potential efficient thermoelectric material.

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