Enhanced Optoelectronic and Thermoelectric Properties in Kagome Rb₂Pt₃S₄: A Probable Energy-Efficient Material

Recent research on kagome materials has shown their multiple applications in diverse fields. Here, we have carried out density functional theory (DFT) calculations to explore the multifaceted properties of a synthesized, but yet less-explored kagome material Rb₂Pt₃S₄. This material is found to be dynamically and mechanically stable. Electronic structure calculations have shown that it is a semiconductor with an indirect band gap ranging from ∼1.28 to 2.34 eV. The major contributions to the density of states around the Fermi level are from the Pt 5d and S 3p orbitals. Optical parameters were computed using a dielectric function, revealing moderate optical reflectivity and conductivity, large optical anisotropy, and optical activity within the ultraviolet region, suggesting that the proposed material is a potential candidate for optoelectronic devices. In addition, temperature- and pressure-dependent thermal properties manifested that the compound studied bears ultralow lattice thermal conductivity with low Debye temperature, low sound velocities, and large Grüneisen parameter. The calculation of transport properties based on the semiclassical Boltzmann theory reveals that Rb₂Pt₃S₄ is a potential candidate for thermoelectric material with optimum figure of merit (ZT) values of ∼1.88 (for n-type) and ∼1.54 (for p-type) at 900 K. Furthermore, the valence band convergence identified in Rb₂Pt₃S₄ plays a significant role in improving the power factor and ZT, suggesting it as an energy-efficient material.