We theoretically investigate structural stability, electronic and thermal characteristic of boron and nitrogen codoped monolayer graphene using density functional theory and Boltzmann transport equation. Three types of BN dimers, ortho, meta, and para dimers, are identified at different concentration ratios of B and N atoms. Our DFT calculations suggest that the BN ortho dimers are structurally favorable configurations due to the lowest required formation energy. At low doping ratio, large bandgap for BN para dimer is predicted leading to high Seebeck coefficient and figure of merit. In addition, a large deviation in the Wiedemann–Franz ratio is also seen, and a maximum value of the Lorenz number is thus found. In contrast, at high doping ratio, high Seebeck coefficient and figure of merit are found for BN ortho dimer and a low Seebeck coefficient for BN para dimer is noticed. Furthermore, a small deviation in Lorenz number is found for high doping ratio where the distance between BN pair is large.

我们使用密度泛函理论和玻尔兹曼输运方程从理论上研究了硼和氮共掺杂单层石墨烯的结构稳定性，电子和热学特性。在B和N原子的不同浓度比下，鉴定出三种类型的BN二聚体：邻，间和对二聚体。我们的DFT计算表明，由于所需的最低形成能，BN邻二聚体是结构上有利的构型。在低掺杂比下，预计BN对二聚体的带隙较大，从而导致高塞贝克系数和品质因数。此外，还发现Wiedemann-Franz比存在较大偏差，因此找到了Lorenz数的最大值。相反，在高掺杂率下，发现BN邻二聚体的塞贝克系数和品质因数较高，而BN对二聚体的塞贝克系数较低。此外，对于BN对之间的距离大的高掺杂率，发现洛伦兹数的较小偏差。