A DFT Insight on the physical, optoelectronic and thermoelectric characteristics of half-Heusler NaZn(N/P) compounds for power generation applications

Abstract

The structural, mechanical, optoelectronic and thermoelectric characteristics of half-Heusler NaZnX (X = N, P) compounds has been explored by utilizing density functional theory. The FP-LAPW system as applied in the WIEN2k code has been used with the exchange-correlation functional of Perdew Burke and Ernzerhof (PBE) and TB-mBJ. The formation and cohesive energy confirms the structural stability and mechanical parameters shows the ductile nature of studied materials. The calculated band structure results show direct band gap along “Γ” of 0.94 eV and 1.60 eV for NaZnN and NaZnP composites, respectively by employing mBJ-GGA potential. Additionally, the study of optical characteristics has involved examining the changes in several parameters as a function of photon energy over a broad range of 0–12 eV. The computed optical parameters showed that NaZnP is best material due to higher value of optical conductivity, dielectric function and higher refractive index. The predicted transport parameters, such as thermal conductivity, power factor, and electrical conductivity, are ideal for thermoelectric gadgets because they tend to rise with temperature. Slack's model is used to compare the temperature-dependent κ_l of hH NaZnX (X = N and P). The BoltzTrap code which is based on the semi-classical Boltzmann Transport theory incorporating the rigid band and constant relaxation time approximation are used. Based on estimated energy band structures, the optical spectra's peaks' origins are found. In the UV field, significant absorption has been expected by this work.