Interlayer coupling and twist-induced modulation of heat transport in multilayer <i>β</i> -bismuthene

Two-dimensional (2D) β-bismuthene has emerged as a promising thermoelectric material owing to its distinctive electronic and thermal properties. Engineering phonon transport through structural parameters such as layer numbers and twist angle provide a powerful strategy for tailoring the thermal behavior of 2D layered materials. In this work, we systematically investigate its thermal transport behavior using molecular dynamics simulations, focusing on the effects of layer number and twist angle. The lattice thermal conductivity increases with layer number from monolayer to five layers but gradually saturates, exhibiting an anomalous layer-dependent trend. In twisted bilayer β-bismuthene, a pronounced 79.2% reduction in in-plane thermal conductivity is observed at a twist angle of θ = 30° compared to θ = 0°, accompanied by a 62.4% decrease in interfacial thermal conductance. Detailed analyses of phonon transmission, density of states, participation ratio, and interfacial potential energy reveal that these reductions arise from suppressed low-frequency phonon transport and weakened interlayer coupling. This work demonstrates that twist angle engineering provides an effective strategy for tuning both in-plane and interfacial thermal transport, offering valuable guidance for designing 2D materials with tailored thermoelectric performance.