Tuning transport properties of B and C sites vacancy defects Graphene/h-BN heterostructures: first-principles study

The goal of this study is to investigate the thermoelectric properties of Graphene/h-BN (G/h-BN), 1B vacancy defect in G/h-BN (G/h-BN_1B), 1C vacancy defect in G/h-BN (G/h-BN_1C) and 2C vacancy defects in G/h-BN (G/h-BN_2C) heterostructures (HS) materials by using first-principles calculations based on spin-polarized DFT-D2 perspective and semi-classical Boltzmann transport theory. We found that all the studied materials are stable. We have computed the Seebeck coefficient (S), thermoelectric power factor (P), electrical conductivity (σ) and electronic contribution of thermal conductivity (K) to study the transport properties of considered materials. The temperature dependent (at constant energy), S of the above materials have positive and negative values at 300 K because the sign of S changes for different types of charge carriers. In addition, it is found that G/h-BN has a symmetry curve but defected materials have slightly asymmetry curves in S verses chemical potential (µ) plot at different constant temperatures. The asymmetry is caused by asymmetric effective mass. We have estimated the P of considered materials by taking constant and found that P of G/h-BN_1B is higher than that of other materials. An expected σ of G/h-BN follows the exponentially increasing nature with an increase in temperature. The σ of defected materials has greater values than that of G/h-BN. In addition, we have calculated the temperature dependent (at constant energy) K of mentioned materials and found them to be increased with the increase in temperatures. K of G/h-BN increases somehow exponentially; however, K of defected materials has a more-less linear nature. Among them, K of G/h-BN_1B retains a higher value at 300 K. By the evaluation of S, P, σ and K, we concluded that defected materials are more promising materials than G/h-BN in the field of thermoelectricity. Graphical abstract