  The electronic and phonon transport properties of graphene-like boron
phosphide (BP), boron arsenide (BAs), and boron antimonide (BSb) monolayers are
investigated using first-principles calculations and Boltzmann theory. By
considering both the phonon-phonon and electron-phonon scatterings, we
demonstrate that the strong bond anharmonicity in the BAs and BSb monolayers
can dramatically suppress the phonon relaxation time but hardly affects that of
electrons. As a consequence, both systems exhibit comparable power factors with
that of the BP monolayer but much lower lattice thermal conductivities.
Accordingly, a maximum ZT values above 3.0 can be achieved in both BAs and BSb
monolayers at optimized carrier concentrations. Interestingly, very similar p-
and n-type thermoelectric performance is observed in the BSb monolayer along
the armchair direction, which is of vital importance in the fabrication of
thermoelectric modules with comparable efficiencies.
