Accurate high-throughput screening of I-II-V 8-electron Half-Heusler compounds for renewable-energy applications

Abstract

Renewable energy resources have emerged as the best alternatives to fossil fuel energy which are rapidly declining with time. Here, eight valence-electron count Half-Heusler(HH) alloys have been studied using reliable first principles calculations in the search of potential candidates for renewable energy applications like thermoelectric (TE), solar harvesting, topological insulator (TI) and transparent conductor (TC) applications. The initial screening parameters used for our study are chemical and thermal stability, band gap, nature of bandgap and band inversion strength. We have performed quasistatic G0W0 calculation starting from HSE groundstate wavefunction to predict the most accurate estimation of bandgap for these class of compounds. A total of 960 compounds were simulated. 121 out of 960 compounds were found to be thermally and chemically stable. 31 compounds with bandgap less than 1.5 eV were studied for thermoelectric application out of which 13 compounds were found to show thermoelectric figure of merit ZT > 0.7 for both p-type and n-type conduction. 30 compounds with band gap 1-1.8 eV were studied for optoelectronic application out of which 13 compounds were found to show Spectroscopic Limited Maximum Efficiency (SLME) more than 20%, comparable to existing state of the art materials. 21 compounds were found to show band inversion at ambient conditions which is a necessary condition for topological insulators. The surface band structure calculations for one of the promising candidate was done to check robustness of the topological behaviour. 29 compounds were found to have bandgap more than 2 eV which are promoted for transparent conductor applications with further band engineering. We strongly believe that our calculations will give useful insights to experimentalists for synthesizing and investigating proposed compounds for different energy applications.