Layered LaCuOSe : A Promising Anisotropic Thermoelectric Material

Thermoelectric (TE) materials can convert temperature difffferences into electricity directly and reversibly without air pollution, which provides a viable route for alleviating global warming and the energy crisis. Here, we use first-principles calculations combined with semiclassical Boltzmann transport theory to assess the potential of layered $\mathrm{La}\mathrm{Cu}\mathrm{O}\mathrm{Se}$ for TE applications. Originating from the layered crystal structure, the electronic and thermal transport properties (i.e., Seebeck coefficient, electrical conductivity, and thermal conductivity) are highly anisotropic between the in-plane and out-of-plane directions. The optimal figure of merit of 2.71 is achieved along the out-of-plane direction for electron doping at 900 K. Such excellent TE properties can be attributed to desired $\mathrm{La}$-$\mathrm{Se}$ interlayer interaction between adjacent layers and relatively strong coupling between acoustic phonons and optical phonons, resulting in simultaneous enhancement of the electrical conductivity and suppression of the lattice thermal conductivity. This study provides an effective route to improve the TE performance of layered $\mathrm{La}\mathrm{Cu}\mathrm{O}\mathrm{Se}$ by utilizing the anisotropic character of transport properties and offers implications in promoting related experimental investigations.