Monolayer SnX (X = O, S, Se): Two-Dimensional Materials with Low Lattice Thermal Conductivities and High Thermoelectric Figures of Merit

Abstract

Thermoelectric materials have attracted great attention due to their important applications in power generation, energy saving, and electric refrigeration. In this article, we designed three two-dimensional materials SnX (X = O, S, Se), which exhibit high stability. All three monolayers are direct band gap semiconductors with a "multivalley" characteristic in band structures, showing bandgaps of 2.87, 1.83, and 1.27 eV for SnO, SnS, and SnSe, respectively. In addition, the SnX monolayers with the optimum power factor values can be up to 0.91−0.97 W m −1 K −2 at room temperature. The small group velocities and strong anharmonic phonon behavior led to an intrinsic lattice thermal conductivity as low as ∼0.92−2.27 W m −1 K −1 . As results, SnX exhibit excellent thermoelectric properties, with the figure of merit (ZT) up to ∼0.07−0.52, ∼0.13−0.89, and ∼0.25−1.41 for SnO, SnS, and SnSe at temperatures of 300−700 K, respectively.

Excellent Thermoelectric Performance of 2D CuMN2 (M = Sb, Bi; N = S, Se) at Room Temperature

“…Obviously, CuSbSe 2 and CuBiSe 2 exhibited larger values than those of CuSbS 2 and CuBiS 2 , and thus have inherently stronger anharmonic interactions, as well as lower . Moreover, the negative γ indicate that these materials may have negative thermal expansion (NTE) properties [ 4 ].…”

“…However, this target is not easy to achieve simultaneously as the parameters above are tightly coupled, mutually restricted, and difficult to decouple. They can be regarded as the functions of the vector tensor , energy eigenvalue , and carrier relaxation time [ 2 , 3 , 4 ]. Besides, the Seebeck coefficient is also closely related to the density of states effective mass ( ) and intrinsic carrier concentration ( n ), [ 5 ].…”

Stability, Electronic Structures, and Thermoelectric Properties of 2D Janus LiZnX (X = N, P, As)

“…39,40 The definitions of parameters in the formulars are the same as in our previous work. 5,6 Although the DPT method may slightly overestimate carrier mobility, it is a relatively accurate way to describe the relaxation times, especially in 2D materials.…”

“…According to the deformation potential theory (DPT), the carrier relaxation times and the carrier mobility can be obtained. , The definitions of parameters in the formulars are the same as in our previous work. , Although the DPT method may slightly overestimate carrier mobility, it is a relatively accurate way to describe the relaxation times, especially in 2D materials.…”

“…Here, k tol is divided into lattice ( k l ) and electron thermal conductivity ( k e ), which is k tol = k e + k l . These parameters can be expressed in the following formulas: − S = 1 e T boldΚ 1 boldΚ 0 − 1 σ = e 2 boldΚ 0 k normale = 1 T ( Κ 2 − Κ 1 2 Κ 0 − 1 ) boldΚ n = 1 4 π 3 ∑ i , boldk τ i ( k ) boldv i ( k ) normal⊗ boldv i ( k ) false[ ε i ( k ) − μ false] n <...…”