Monolayer boron-graphdiyne as a potential thermoelectric material

Motivated by the recent experimental synthesis of two-dimensional (2D) boron-graphdiyne (BGDY), a π-conjugated structure made from a merely sp carbon skeleton connected with boron atoms, we systematically investigate the electronic and phonon transport properties of the monolayer BGDY using first-principles density functional theory (DFT) combined with semiclassical Boltzmann transport theory. Our calculations reveal that the monolayer BGDY, as a newly developed member of 2D carbon-based material, is a direct-bandgap semiconductor with a bandgap of 1.29 eV. Its low carrier effective mass and high carrier mobility contribute to a high power factor. Meanwhile, strong phonon scattering leads to an exceptionally low phonon thermal conductivity of 2.4 Wm−1 K−1 at 300 K. The combination of ultralow phonon thermal conductivity and a high power factor results in outstanding thermoelectric performance, with maximum figure of merit (ZT) values ranging from 2.2 to 4.3 for n-type and 1.5 to 2.8 for p-type monolayer BGDY at moderate carrier concentrations across temperatures from 300 to 700 K. This study highlights the promising potential of the monolayer BGDY for medium-temperature thermoelectric applications.