Orbital-resolved tuning of electronic thermal conductivity in monolayer h-B2O via doping in the diffusive regime

Abstract

Abstract The highly stable two-dimensional monolayer honeycomb borophene oxide (h-B 2 O) has attracted considerable interest due to its unique topological features and potential superconducting behavior. In this study, a tight-binding Hamiltonian is constructed by incorporating the P y and P z orbitals of boron, effectively capturing the essential physics governing the material’s low-energy electronic behavior. Additionally, for the first time, the electronic thermal conductivity (ETC) of monolayer h-B2O is calculated using the Kubo-Greenwood formalism within the diffusive transport regime. The results reveal strong anisotropy ( $$\:{\kappa\:}_{yy}\gg\:{\kappa\:}_{xx}$$ ), with room-temperature ETC values of $$\:5.9\times\:{10}^{-2}$$ mW m $$\:{}^{-1}$$ K $$\:{}^{-1}$$ , 1 mW m $$\:{}^{-1}$$ K $$\:{}^{-1}$$ , and 0.17 mW m $$\:{}^{-1}$$ K $$\:{}^{-1}$$ along the armchair $$\:({\kappa\:}_{xx}$$ ), zigzag $$\:({\kappa\:}_{yy}$$ ), and anomalous Righi-Leduc effect $$\:({\kappa\:}_{xy}$$ ) directions, respectively. Furthermore, we systematically investigate the impact of impurity-induced disorder on ETC in h-B 2 O under both n-type and p-type doping, employing the T-matrix approximation. In the n-type regime, increasing impurity concentration $$\:{n}_{i}$$ = 2%, 4%, 6% leads to a significant enhancement of the ETC associated with the out-of-plane P z orbital, attributed to its favorable spatial orientation and higher carrier occupancy. Conversely, the in-plane P y orbital exhibits a reduction in ETC due to increased localization and enhanced electron-electron scattering. Despite this orbital contrast, the total ETC rises along all crystallographic directions, governed by the dominant contribution of the P z orbital, thereby revealing strong orbital-resolved behavior and pronounced directional anisotropy. In contrast, p-type doping induces only modest changes: the ETC contribution from the P y orbital slightly increases, while that of the P z orbital is marginally reduced, resulting in an overall weak response of the total ETC. These findings highlight the crucial role of orbital symmetry, spatial orientation, and dopant type in shaping the anisotropic and tunable thermal transport properties of h-B 2 O. The thermal resilience under p-type doping, alongside the direction-dependent enhancement under n-type doping, positions h-B 2 O as a promising candidate for nanoscale thermoelectric and thermal management technologies.