Structure and thermal boundary resistance of basal plane twin boundaries in Bi2Te3†

The nanostructuring of thermoelectric materials is a well-established method of suppressing lattice thermal conductivity. However, our understanding of the interfaces that form as a result of nanostructure engineering is still limited. In this work, we utilise a simple two-body pair potential to calculate the thermal boundary resistance of basal plane twin boundaries in Bi₂Te₃ at 300 K using reverse non-equilibrium molecular dynamics simulations. The considered interatomic potential gives an excellent description of the twin boundary formation energies and the lattice thermal conductivity of bulk Bi₂Te₃. Using this potential, we find that the twin boundary located at the Bi layer is not thermally stable (unlike those located at the Te layers), and undergoes a phase transition into two distinct structures. We compare the thermal boundary resistance across these different twin boundaries and link the observed trends to overall geometry, van der Waals gap sizes and degree of structural disorder in atomic layers near the boundary.