A nanotwin-based physical model for designing robust layered bismuth telluride thermoelectric semiconductor

The inherent weak van der Waals (vdW) interaction of Bi2Te3semiconductors results in inferior strength, limiting their micromachining into urgently needed thermoelectric microdevices for 5G and the Internet of Things. Here, we report the effect of twin boundary (TB) spacingλand orientationθon strength. A physical model of the inverse proportional function betweenλand shear strength is developed based on the TBs hindered vdW layer slippage. Then, we establish a sine function model ofθand shear strength based on the bond strain characteristics. Notably, the shear strength (1.64 GPa) of nanotwinned Bi2Te3withλ= 2.42nm andθ= 80.54° is 2.5 times higher than that of the flawless single crystal. Moreover, we build a function model betweenλ and the lattice thermal conductivity κ_Lbased on the temperature jump caused by TBs obstructed heat flow. These models provide the basis for developing robust and efficient thermoelectric materials. ; © 2024 The Author(s). Under a Creative Commonslicense - Attribution-NonCommercial-NoDerivs 4.0 International ; This work was supported by theNational Natural Science Foundation of China(nos.52022074,92163119,92163212, and92163215) and theKnowledge Innovation Program of Wuhan-Basic Research(2022010801010177). W.A.G. is supported by theUS National Science Foundation(CBET-2005250 Robert McCabe). ; Conceptualization, G.L., W.A.G., and B.D. Methodology, X.H. and X.Z. Investigation, X.H., X.Z., L.W., and X.F. Writing – original draft, X.H. and L.W. Writing – review & editing, X.H., G.L., and W.A.G. Funding acquisition, G.L., W.A.G., B.D., and P.Z. Supervision, Q.Z. Resources, G.L., B.D., and X.F. Validation, X.H. and G.L. Visualization, X.H. and L.W. ; The authors declare no competing interests. ; Download allsupplementary filesincluded with this article