Thermoelectric properties of C₂P₄ monolayer: A first principle study

We have theoretically explored the electronic and thermoelectric properties of the C₂P₄ monolayer with the interface of density functional theory and semi-classical transport theory. Our calculation shows a high Seebeck coefficient and low electronic thermal conductivity in the vicinity of zero chemical potential (μ = 0), resulting in a good power factor (PF) and a high figure of merit (ZT). More particularly, the electronic figure of merit (ZT_e) exhibits two high peak values around μ = 0 due to the significant contribution of thermoelectric parameters. Furthermore, ZT_e decreases by increasing the temperature, giving a peak value of 0.98 in the negative chemical potential (μ), whereas, for μ > 0, the peak value increases slightly with temperature. Additionally, the ZT_e peak value is robust against ±10% of uni- and biaxial strains at room temperature. To make our calculation more realistic, we add phonon contributions to the thermal conductivity in pristine C₂P₄ and calculate the total ZT. We have found that phonon contribution dominates at low temperatures, and the ZT peak is reduced to 0.78. These optimal thermoelectric parameters of the C₂P₄ monolayer may be suitable for demonstrating the feasibility of a good thermoelectric material.