First principle study of opto-electronic and thermoelectric properties of Zintl Phase XIn(2)Z(2) (X = Ca, Sr and Z = As, Sb)

Abstract

In the realm of DFT, the optoelectronic and thermoelectric properties of Zintl phase XIn(2)Z(2) (X = Ca, Sr and Z = As, Sb) compounds are studied in P63/mmc symmetry. The estimated structural properties are well agreement with the experimental work. Their cohesive energy and enthalpy demonstrate the thermodynamic stability of these compounds. X In2As2 compounds are direct bandgap semiconductors at Gamma symmetry, XIn2Sb2 compounds are indirect bandgap semiconductors at M symmetry, according to electronic characteristics. The direct bandgap values range from 0.209 to 0.894 eV, whereas the indirect bandgaps lies in rang of 0.211-0.281 eV. With the replacement of As with Sb, not only the transition of bandgap occurs from direct to indirect and also decrease the bandgap of the understudy compounds. All of the substances are optically active in the infrared range of the electromagnetic spectrum, based on their optical properties. The optical characteristics suggest that they could be employed in optoelectronic devices. Due to low band gap and high value of ZT of the compound SrIn2Sb2; it is more suitable for thermoelectric applications then the rest compounds. The thermoelectric properties indicate that they are helpful as active thermoelectric materials in the fields of thermoelectric cooling, thermoelectric power production for wearable systems, thermoelectric Peltier micro coolers, and thermoelectric generation, as well as nano-thermocouples.