Weak interlayer dependence of lattice thermal conductivity on stacking thickness of penta-graphene

Penta-graphene (PG), as a novel carbon allotrope, has attracted considerable attention because of its unique atomic structure and outstanding intrinsic properties. Here, we systematically investigate the effect of layer numbers on the lattice thermal conductivity of the stacked PG structures by solving exactly the linearized phonon Boltzmann transport equation combined with first-principles calculations. We find that the lattice thermal conductivity of the stacked PG is insensitive to the number of layers, which is in sharp contrast to that of graphene. Such a layer-independent thermal conductivity is attributed to the buckled structure of PG which breaks the two-dimensional selection rule of three-phonon scattering and the weak van der Waals interlayer interactions that hardly have any effect on the lattice thermal conductivity. This mechanism can be generalized to other van der Waals layered materials with buckled or puckled structures, which may also show the layer-independent lattice thermal conductivity.