Tunable thermal transport properties of bilayer GeS with stacking patterns

The stacking of 2D layered materials can be an effective tool to modulate low-dimensional electronic structures and transport properties. In this work, using first-principles calculations, the thermal transport properties of a GeS bilayer are systematically investigated by solving the phonon Boltzmann transport equation. Various stacking configurations for bilayer GeS are introduced, and two dynamically stable structures are confirmed. The results indicate that the thermal transport property of the GeS bilayer can be dramatically suppressed due to a decreased phonon relaxation time, which is dependent on the stacking patterns and interlayer distances. The underlying phonon transport mechanisms and the stacking effects on the lattice thermal conductivity for bilayer GeS are further revealed through a comparative study among monolayer, bilayer, and bulk GeS. In addition, the in-plane anisotropy of the thermal transport properties is also enhanced for the GeS bilayer, which is also found to be dependent on the stacking pattern. The significantly suppressed thermal conductivity for the GeS bilayer evaluated in this work implies great potential for 2D multilayer-based thermoelectric devices and applications.