First-principles calculations of electronic structure and optical and elastic properties of the novel ABX-type LaWN perovskite structure.

The development of ABX-type advanced perovskite materials has become a focus for both scientific researchers and the material genome initiative (MGI). In addition to the traditional perovskite ABO and halide perovskite ABX, LaWN is discovered as a new ABX-type advanced perovskite structure. The elastic and optical properties of this novel LaWN structure are systematically studied DFT. Based on the calculated elastic constants, the bulk modulus, shear modulus, Young's modulus and Pugh modulus ratio are precisely obtained. Results show that (1) LaWN is an indirect bandgap semiconductor with a hybrid occuring near the Fermi level and the main contributions are La-d, W-d and N-p. (2) LaWN has a certain ductility. The optical constants, such as absorption spectrum, energy-loss spectrum, conductivity, dielectric function, reflectivity and refractive index, are analyzed and the static dielectric constant is 10.98 and the refractivity index is 3.31. (3) The optical constants of LaWN are higher than those of other existing ABX-type materials, showing very promising application as a functional perovskite in the future. The existence of this stable LaWN structure might widen the perovskite material's application, such as in photodetectors, light-emitting diodes, perovskite solar cells, fuel cells and so on.