The intrinsic shear strength (1.25 GPa) of In₄Se₃ remarkably lower than those of classic thermoelectric (TE) materials such as CoSb₃ (7.17 GPa), PbTe (3.46 GPa), TiNiSn (10.52 GPa), which limits the commercial applications of In₄Se₃ based TE materials. To improve the shear strength of single-crystalline In₄Se₃, we used density functional theory to study the influence of point defects on the mechanical behavior of In₄Se₃ under the pure shear loading. We found that doping with Ca, Ag, Yb, Pb, Zn, I, and Br can improve the shear strength of In₄Se₃. In particular, Ca-doped In₄Se₃ obtained the highest shear strength (1.43 GPa), an increase of 14.4%. These point defects can improve the van der Waals interaction between In/Se layers significantly, hence enhancing the shear strength, while the slippage between the In/Se layers is still predominating its deformation and failure. Our work offers a possibility in strengthening layered materials with robust mechanical properties.

In ₄ Se ₃的固有剪切强度（1.25 GPa）明显低于经典热电（TE）材料，例如 CoSb ₃（7.17 GPa）、PbTe（3.46 GPa）、TiNiSn（10.52 GPa），这限制了商业应用基于 In ₄ Se ₃的 TE 材料。为提高单晶In ₄ Se ₃的剪切强度，我们利用密度泛函理论研究了点缺陷对纯剪切载荷下In ₄ Se ₃力学行为的影响。我们发现掺杂Ca、Ag、Yb、Pb、Zn、I和Br可以提高In ₄ Se ₃的剪切强度。. 特别是Ca掺杂的In ₄ Se ₃获得了最高的剪切强度（1.43 GPa），增加了14.4%。这些点缺陷可以显着改善 In/Se 层之间的范德华相互作用，从而提高剪切强度，而 In/Se 层之间的滑移仍然是其变形和失效的主要因素。我们的工作为增强具有强大机械性能的层状材料提供了可能性。