Probing the thermoelectric and optical performance of half-Heusler PtZrX (X = Si, Ge) semiconductors: a first principles investigation

Abstract

In this study, we employed first-principles calculations based on density functional theory (DFT) implemented within the WIEN2k code to investigate the comprehensive material properties of PtZrX alloys (X = Si, Ge). This investigation encompassed structural, mechanical, electronic, thermal, optical, and thermoelectric characteristics. The lattice parameters, bulk modulus, and cohesive energy of these alloys were determined under the conditions of absolute zero temperature (0 K) and ambient pressure (0 GPa). The obtained results demonstrate that PtZrSi and PtZrGe exhibit both anisotropic and elastically stable characteristics. Furthermore, both alloys display indirect bandgap semiconducting behavior with bandgaps of 1.43 eV and 1.32 eV for PtZrSi and PtZrGe, respectively. We utilize density functional perturbation theory (DFPT) to predict the dynamical behavior of these ordered systems. The calculated standard enthalpy of formation further corroborates their thermodynamic stability. Analysis of Young's and shear modulus revealed that PtZrSi possesses superior stiffness compared to PtZrGe. The dielectric function was employed to explore the optical properties, suggesting potential applications in optoelectronics, as corroborated by the analysis of the optical spectra. Moreover, this research suggests the potential of these alloys as efficient thermal insulators for solar heating applications. Finally, the BoltzTrap code was utilized to compute the temperature-dependent thermoelectric properties, providing valuable insights into their potential applications in thermoelectric devices.