Thermoelectric materials play a crucial role in energy conversion technologies by enabling the direct transformation of heat into electricity, offering a promising route for sustainable energy harvesting. This study investigates the thermoelectric properties of the two-dimensional \(\hbox {Sn}_4\) \(\hbox {Sb}_8\) monolayer using first-principles calculations within the density functional theory (DFT) framework, combined with Boltzmann transport theory. We systematically compute the electrical conductivity, Seebeck coefficient, and electronic contribution to thermal conductivity using the BoltzTraP code. At the same time, the relaxation time is determined via an Arrhenius approach, enabling the estimation of absolute transport coefficients. The lattice thermal conductivity is also obtained through a semi-empirical method that accounts for phonon contributions. The thermoelectric figure of merit (ZT) is evaluated across various chemical potentials and temperatures, revealing strong anisotropy between the x and y transport directions. At room temperature ( \(T = 300\) K), the maximum ZT values reach 0.5 for electrons and 0.35 for holes. As the temperature increases, the thermoelectric efficiency improves, with the highest ZT reaching 0.81 for electrons along the x direction at \(T = 900\) K. At the same time, hole transport becomes nearly isotropic with \(ZT = 0.72\) in both directions. These results establish \(\hbox {Sn}_4\) \(\hbox {Sb}_8\) as a strong candidate for thermoelectric applications, demonstrating significant efficiency from ambient to high temperatures. The material’s favorable transport properties and high ZT values make it an excellent prospect for energy conversion technologies. Future research should focus on experimental validation and potential optimizations through strain engineering and doping strategies to enhance performance.
