Ultrahigh power factors in P-type 1 T-ZrX2 (X =S, Se) single layers

• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2017,（22）
• 页码范围: 1530-1537
• 页数: 8页
• 语种: 英文

摘要

The thermoelectric performances of 1T-ZrX2 (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 =S2σ) were found in the P-type compounds;these values were ～ 11.95 and ～13.58 mW K 2 m-1 for 1T-ZrS2 and 1T-ZrSe2 single layers,respectively.However,because of the Lorenz relation between the electrical conductivity (σ) and an electron's thermal conductivity (κel) given by the Wiedemann-Franz law,the electronic figures of merit (ZesT =PF.T/κel) at 300 K were approximately 0.67 and 0.75 for the N-and P-type 1T-ZrSe2,respectively.In addition,the lattice thermal conductivities (κph) were calculated,giving values of ～1.43 and ～0.97 W K-1 m-1 for 1T-ZrS2 and 1T-ZrSe2 single layers,respectively.Therefore,because of the lowerκph/κel ratio,the P-type 1T-ZrX2single layers possess higher figure-of-merits (ZT =ZelT/ (1 +κph/κel)) than their counterparts.This signifies that the P-type samples demonstrate better thermoelectric performance than the N-type ones.The thermoelectric prooerties of metastable 2H-ZrX2 (X =S and Se) single layers were also investigated.