Tensile strain as an efficient way to tune transport properties of Graphdiyne/Borophene hetero-bilayers; a first principle investigation

Abstract

Thermoelectric materials have attracted much attention due to their crucial role in heat conversion and cooling applications. Transport properties effectively conduct thermoelectricity efficiency, and therefore, many studies have particularly focused on enhancing these features. In the present study, through periodic density functional theory combined with semi-classical transport formulations, the influence of strain on thermoelectric characteristics of Graphdiyne/Borophene hetero-bilayers has been investigated. Based on mechanical properties data, we have shown that bilayer construction causes an increase in the ultimate stress of constituent monolayers. The maximum strain that each hetero-bilayer can withstand is determined by using stress-strain behavior. Among the studied hetero-bilayers, GBS0 has the most value of Young’s modulus [1,2] under equibiaxial strain. Temperature-dependent transport properties of strained hetero-bilayers suggest strain as an efficient way to tune the thermoelectric behavior of hetero-bilayers. The introduction of uni- and biaxial strains affects the electrical and thermal conductivity of GBS0 and GBS1. Furthermore, the power factor and figure of merit, as the key elements of thermoelectric devices, can be significantly engineered under external tensions. The impact of tensile strain on the Seebeck effect is disclosed. Surprisingly, the studied hetero-bilayers can possess either positive or negative Seebeck coefficients under different modes of external strains. The present research extends the strain field, particularly in the rational design of thermoelectric devices.