Ab initio study of the optoelectronic properties and high-temperature thermoelectric performance of bulk SrLiP

Abstract

In this work, a systematic first-principles investigation of the structural, electronic, optical, and thermoelectric properties of bulk SrLiP is performed within the framework of density functional theory (DFT), using the Perdew–Burke–Ernzerhof (PBE) version of the generalized gradient approximation and the modified Becke–Johnson (mBJ) exchange potential. The optimized crystal structure confirms the stability of the hexagonal phase, while the calculated elastic constants satisfy the mechanical stability criteria, demonstrating that SrLiP is a mechanically robust compound with moderate elastic anisotropy. The electronic band structure reveals that bulk SrLiP is a direct band gap semiconductor, with band-gap values of 0.852 eV and 1.842 eV obtained using the PBE and mBJ functionals, respectively. The optical response exhibits moderate anisotropy, characterized by strong absorption in the visible and ultraviolet regions, relatively low reflectivity, and pronounced dielectric behavior, highlighting the suitability of SrLiP for optoelectronic applications. Furthermore, the thermoelectric transport properties, evaluated using the BoltzTraP2 code within the semiclassical Boltzmann transport framework, reveal a significant improvement in thermoelectric performance with increasing temperature. The combined effect of a relatively high Seebeck coefficient, enhanced electrical conductivity, and reduced thermal conductivity results in a maximum thermoelectric figure of merit of approximately 0.61 at 900 K. Overall, these findings establish bulk SrLiP as a mechanically stable semiconductor with promising potential for high-temperature thermoelectric energy-conversion and optoelectronic applications.