Thermoelectric transport properties of 2D semiconducting MXene Ti2CO2 with a large figure of merit

Abstract

We have theoretically investigated the thermoelectric transport properties of a two-dimensional (2D) MXene Ti2CO2 monolayer. To evaluate the thermoelectric coefficients, Rode’s iterative technique is employed to solve the Boltzmann transport equation by taking inputs from ab initio calculations. Explicitly, the effect of three realistic scattering mechanisms, namely, acoustic deformation potential (ADP), piezoelectric (PZ), and polar optical phonons (POPs), is considered in calculating electrical conductivity (σ), Seebeck coefficient (S), power factor (PF), and thermoelectric figure of merit (ZT). These coefficients are investigated as a function of temperature (T = 50–700 K) and carrier concentration (n = 1×1011–1×1014cm−2). The scattering by ADP is found to largely limit these transport coefficients. The σ (or S) is found to decrease (or increase) with T, whereas they are, respectively, increasing and decreasing with n. The lattice thermal conductivity (κL) calculated from the modified Callaway–Klemens formula is used in calculating ZT, which is ≈30–120 Wm−1K−1 in the temperature range considered. At T = 300 K, a large ZT (2 < ZT < 3) for n = 1×1013–1×1014cm−2 is predicted, which is manifestation of high σ, large S, and small κL. The results show Ti2CO2 as a potential thermoelectric 2D material and offer theoretical support for further investigations.