Exploring a Superlattice of SnO-PbO: A New Material for Thermoelectric Applications

There exist an exponentially large number of oxide materials with equally large number of crystal structures for applications in innumerable fields due to their low toxicity, affordable cost, and good stability in air. These may play a vital role in the energy crisis that the world is facing today if they can be efficiently utilized as high-performance thermoelectric material in the 21st century. In this context, there has been an exploration of a layered oxide material, SnO-PbO, in their solid solution. Our ab-initio calculations indicate that the layered crystal structure is dynamically and thermodynamically stable at ambient as well as at higher temperatures. Furthermore, the lone pair associated with Sn and Pb atoms introduces crystallographic anisotropy which strongly scatters heat-carrying acoustics phonons and consequently reduces lattice thermal conductivity. On the other hand, degenerate bands and sharp peaks in the electronic density of states give rise to higher Seebeck coefficient and covalent bonding of Sn–O and Pb–O facilitates moderate electrical conductivity. In this work, deformation potential theory coupled with Boltzmann transport formalism has been adopted to obtain carrier scattering information involving charge carrier mobility and hence carrier conductivity. As a consequence of this bonding hierarchy and crystallographic anisotropy, SnO-PbO could be availed as a next generation oxide based thermoelectric material.