Complex superlattice unit cell designs for reduced thermal conductivity

The suitability of the Green--Kubo method for predicting the thermal conductivity of nanocomposites is assessed by studying model Lennard-Jones superlattices. Good agreement is found when comparing the predicted cross-plane thermal conductivities to independent predictions from the direct method. The link between the superlattice unit cell design and the thermal conductivity tensor is then explored. We find that complex, multilayered unit cell designs can reduce the cross-plane thermal conductivity by 17% compared to the minimum value predicted for superlattices with only two layers in the unit cell. These results suggest new directions that can be explored for reducing thermal conductivity, which is desirable in applications such as designing materials for thermoelectric energy conversion.