Ultralow lattice thermal conductivity and anisotropic thermoelectric performance of AA stacked SnSe bilayer

The low-temperature bulk phase of SnSe has a layered structure with AB-type of stacking of two-atom-thick SnSe monolayers. However, in the case of bilayers the AA-stacked SnSe bilayer structure is most stable. Similar to bulk SnSe, AA-stacked SnSe bilayer has ultralow lattice thermal conductivity of 0.90 Wm(-1) K-1 at room temperature which is quite low as compared to other two dimensional materials. Our results show that n-type SnSe bilayer has good thermoelectric performance as compared to that of the p-type bilayer.