Insight to the Structural, Electronic, Optical, and Thermoelectric Properties of NaCaSb and KCaSb Half Heusler Compounds: A DFT Approach

Full-potential, linearized augmented plane wave approach (FP LAPW), as employed in Wien2K code was utilized to analyze structural, elastic, optoelectronic, and transport features of NaCaSb and KCaSb half–Heusler (HH) compounds. Generalized gradient approximation (GGA) was considered for structural optimization. The predicted lattice constants are in line with the prior theoretical and experimental findings. The examined NaCaSb and KCaSb compounds are inherently ductile and mechanically stable. The investigated HHs are semiconductors with a band gap 1.27 and 1.23 eV for NaCaSb and KCaSb, respectively, in the modified Becke–Johnson (mBJ) approximation. Calculated optical characteristics of NaCaSb and KCaSb point to their potential applicability in optoelectronic devices. Thermoelectric features were analyzed employing the Boltzmann transport provided in the BoltzTraP software. At room temperature, the significant figure of merit (ZT) values indicates that the investigated NaCaSb and KCaSb can be used for fabricating thermoelectric devices with the highest possible efficiency.