van der Waals heterostructure PtS2 /MoSi2 P4 for advanced thermoelectric and photovoltaic applications

Abstract

This study explores a van der Waals heterostructure (vdWH) PtS₂/MoSi₂P₄ as a potential candidate material for sustainable energy applications in thermoelectrics and photovoltaics. This heterostructure exhibits a small lattice mismatch of ∼3%, indicating excellent interlayer compatibility. The phonon spectrum reveals the absence of imaginary frequencies across the Brillouin zone, indicating dynamic stability. These characteristics suggest that vdWH PtS₂/MoSi₂P₄ offers robust structural integrity and synthesis feasibility for next-generation energy devices. This heterostructure exhibits a direct band gap of 0.98 eV with the spin–orbit coupling effect, as calculated using the Heyd–Scuseria–Ernzerhof hybrid functional. Moreover, this heterostructure demonstrates a considerable static dielectric constant of 7.25 as well as an optical absorption coefficient of 2.5 × 10⁵ cm⁻¹ in the visible region. A rigorous optical absorption is found in the ultraviolet region. The computed spectroscopic limited maximum efficiency (SLME) of approximately 27%, compared to those of conventional high-performance thin-film absorber materials, suggests its potential as a highly efficient photovoltaic absorber material. Our investigation reveals a higher Seebeck effect due to p-type carriers at both temperatures as compared to n-type carriers. The vdWH PtS₂/MoSi₂P₄ has low lattice thermal conductivities (κ_l) of 2.8 W m⁻¹ K⁻¹ at 300 K and 0.8 W m⁻¹ K⁻¹ at 600 K. The calculated figure of merit (ZT) of 0.27 at 600 K is mainly due to the enhanced thermoelectric performance quantified by the term S²σ/τ, where S, σ, and τ denote the Seebeck coefficient, electrical conductivity, and relaxation time of charge carriers, respectively. This investigation reveals that vdWH PtS₂/MoSi₂P₄ holds considerable promise as a highly suitable candidate for next-generation photovoltaic and thermoelectric applications.