Effect of vacancies on structural, electronic, elastic, and thermoelectric properties of CdIn[formula omitted]Se[formula omitted] defect chalcopyrite-type semiconductor: An ab-initio approach

Abstract

In this work, we have investigated the detailed structural, electronic, elastic, mechanical and thermoelectric properties of pure (CdInSe2) and defect (CdIn2Se4) chalcopyrite-type semiconductors using the ab-initio approach within the density functional theory along with semi-classical Boltzmann transport theory. The structural properties reveal the pure structure is more distorted than the defect one. The electronic band structure infers that the pure structure is an n-type semiconductor while the defect one is an intrinsic semiconductor having a larger bandgap as compared to the former due to the cationic vacancy. Both compounds are direct bandgap semiconductors. From the calculation of elastic stiffness constants and elastic moduli, it is found that both the compounds are mechanically stable. The melting temperature of CdInSe2 and CdIn2Se4 are obtained as 831 K and 784 K, respectively. The electronic thermoelectric properties show a higher value of ZT = 0.86 for the ordered vacancy compound (CdIn2Se4) with a fixed hole concentration of 1020 cm−3 at 800K making it competent for the thermoelectric applications. The variation of various thermoelectric coefficients w.r.t. the chemical potential shows that in CdIn2Se4, the p-type doping is favorable to further enhance the thermoelectric behavior. The lattice thermal conductivity for the defect structure is found to be 3.78 W/mK at room temperature and a lowest value of 1.421 W/mK at 800K. The results demonstrate the defect CdIn2Se4 as a promising thermoelectric material.