Tailoring graphene for thermoelectric: Theoretical insights into position-dependent effects of BN Co-doping

We present a comprehensive theoretical investigation of the structural, electronic, dynamical, transport, and thermoelectric properties of pristine graphene (C8) and boron–nitrogen (BN) co-doped graphene using density functional theory. Motivating from previous work of varying the relative positions of B and N dopants at ortho, meta, and para sites, leads to the enhancement in electronic thermal conductivity. We investigate position dependence of B and N co-doped graphene properties, with the phonon dispersion analysis, we confirm the dynamical stability of the BN co-doped systems. Among the configurations studied, C6BN₁, and C6BN₃ exhibit p-type semiconducting behaviour, while C6BN₂ shows n-type characteristics. The Seebeck coefficient (S) and electrical conductivity (σ) increase with temperature, indicating strong thermoelectric potential. Fixing the position of boron, while varying the nitrogen doping site (para, meta, ortho) leads to phonon scattering at low frequencies, reducing thermal conductivity and enhancing thermoelectric performance. Notably, the figure of merit (ZT) for C6BN₁ reaches 2.30 at 800 K, demonstrating excellent thermoelectric efficiency. These results highlight the promising role of position-dependent BN co-doping in tailoring graphene's properties for advanced thermoelectric applications.