Thermoelectric and Optical Properties of Half–Heusler Compounds RbYX (X = Si, Ge): a First Principle Study

In the present work, the optical, elastic, and thermoelectric properties of RbYX (X = Si, Ge) half-Heusler (h–H) compounds are investigated. These compounds have 8 valence electrons. Thequantum mechanical model, known as density functionaltheory (DFT) and WIEN2k simulation package are used to investigate the elastic, optical, and thermoelectric properties. Further, the full Potential (FP)—LAPW approach is used to conduct the computations. The measured optimized lattice constants of 7.2 and 7.3 Å for RbYSi and RbYGe are obtained. The density of states (TDOS and PDOS) as well as band structure are studied and analyzed. The direct–energy band gap. of 0.61 and 0.63 eV are observed which shows the semiconducting behavior of the alloys. The measured optical reflectivity of RbYX (X = Si, Ge) lies in the ultra-violet region (UV). The absorption coefficients greater than 104 cm−1 are observed in the visible and ultraviolet regions. The other optical properties like the refractive index (n), electron-energy loss (I), extinction coefficient (K), and optical conductivity ( \(\sigma\) ) were also investigated using the dielectric function. Results revealed that the alloys are promising candidates for optoelectronic and photovoltaic. The thermoelectric properties are also calculated using the Boltzmann. transport equations included in the BoltzTraP2 package. The calculated power factor for RbYSi and RbYGe are 4.18 × 1011 WK−2 cm−1 s−1 and 4.0 × 1011 WK−2 cm−1 s−1. The results revealed that these p-type semiconductors are suitable candidates for good thermoelectric responses.