Zhen Ying-Xiang, Yang Ming, Zhang Hang, Fu Guang-Sheng, Wang Jiang-Long, Wang Shu-Fang, Wang Rui-Ning
Hebei Key Laboratory of Optic-Electronic Information and Materials, College of Physics Science and Technology, Hebei University, Baoding 071002, China.
Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China.
Sci Bull (Beijing). 2017 Nov 30;62(22):1530-1537. doi: 10.1016/j.scib.2017.10.022. Epub 2017 Oct 28.
The thermoelectric performances of 1T-ZrX (X = S and Se) single layers were investigated using a combination of density functional calculations and semi-classical Boltzmann transport theory. Because of the high hole mobilities at 300 K, ultrahigh power factors (PF=Sσ) were found in the P-type compounds; these values were ∼ 11.95 and ∼13.58 mW K m for 1T-ZrS and 1T-ZrSe single layers, respectively. However, because of the Lorenz relation between the electrical conductivity (σ) and an electron's thermal conductivity (κ) given by the Wiedemann-Franz law, the electronic figures of merit (ZT=PF·T/κ) at 300 K were approximately 0.67 and 0.75 for the N- and P-type 1T-ZrSe, respectively. In addition, the lattice thermal conductivities (κ) were calculated, giving values of ∼1.43 and ∼0.97 W K m for 1T-ZrS and 1T-ZrSe single layers, respectively. Therefore, because of the lower κ/κ ratio, the P-type 1T-ZrX single layers possess higher figure-of-merits (ZT=ZT/1+κκ) than their counterparts. This signifies that the P-type samples demonstrate better thermoelectric performance than the N-type ones. The thermoelectric properties of metastable 2H-ZrX (X = S and Se) single layers were also investigated.
采用密度泛函计算和半经典玻尔兹曼输运理论相结合的方法，研究了1T-ZrX（X = S和Se）单层的热电性能。由于在300 K时具有高空穴迁移率，在P型化合物中发现了超高功率因子（PF = Sσ）；对于1T-ZrS和1T-ZrSe单层，这些值分别约为11.95和13.58 mW K⁻¹ m⁻²。然而，根据维德曼-夫兰兹定律给出的电导率（σ）与电子热导率（κ）之间的洛伦兹关系，对于N型和P型1T-ZrSe，300 K时的电子品质因数（ZT = PF·T/κ）分别约为0.67和0.75。此外，还计算了晶格热导率（κ），对于1T-ZrS和1T-ZrSe单层，其值分别约为1.43和0.97 W K⁻¹ m⁻¹。因此，由于κ/κ比值较低，P型1T-ZrX单层比其对应的N型单层具有更高的品质因数（ZT = ZT/1 + κ/κ）。这表明P型样品的热电性能优于N型样品。还研究了亚稳2H-ZrX（X = S和Se）单层的热电性能。
