Nowotny-Juza phase KBeX (X = N, P, As, Sb, and Bi) half-Heusler compounds: applicability in photovoltaics and thermoelectric generators.

In the present research, we have considered KBeX (X = N, P, As, Sb, and Bi) half-Heusler compounds to study their inherent properties and have used FP-LAPW + lo scheme with density functional theory based WIEN2k package. The structural and band structural parameters have been explained, and various optical, thermoelectric, and thermodynamic parameters of half-Heuslers have also been analyzed in detail. The trend followed by the lattice constant of these materials approves the reliability of this investigation. The band structures show all the materials are direct band gap semiconductors except KBeN. Here, we have noticed that absorption is highest, and optical conductivity is also highest, confirming the theoretical concept and thus the accuracy of the projected outcomes. All materials (except KBeBi) show a figure of merit near unity in both p- and n-regions, and a small decay is observed with increasing temperature, which affirms their potential as thermoelectric candidates in both p- and n-regions at room temperature. Since conventional resources are limited in nature and their vanishing rate is more than their reproduction rate, hence to fulfil the high energy demand, it has become necessary to search for renewable energy resources. Herein, the values of optical and thermoelectric parameters confirm the photovoltaic and thermoelectric applications of these materials.