Tuning the electronic and optical properties of graphane/silicane and fhBN/silicane nanosheets via interfacial dihydrogen bonding and electrical field control

Abstract

In this work, using density functional theory (DFT) with van der Waals (vdW) corrections, the effects of dihydrogen bonding on the stability, electronic and optical properties of a graphane/silicane heterobilayer and a fully hydrogenated hexagonal boron nitride (fhBN)/silicane heterobilayer were investigated. Our results reveal that dihydrogen bonding at the interface (C–H⋯H–Si, N–H⋯H–Si or B–H⋯H–Si) would induce interface polarizations, which greatly modulate the electronic and optical properties of the heterobilayers. Moreover, the stability and electronic properties of the graphane/silicane heterobilayer and the fhBN/silicane heterobilayer can be tuned with electric fields (E-fields), yielding not only the band gap of the heterobilayers in a semiconductor–metal transition but also widely tunable binding strengths. More importantly, the mobilities of the graphane/silicane heterobilayer and the fhBN/silicane heterobilayer we predicted are electron-dominated, reasonably high (improvable up to 170 cm² V⁻¹ s⁻¹ for the graphane/silicane heterobilayer and ∼550 cm² V⁻¹ s⁻¹ for the fhBN/silicane heterobilayer along the Γ–M direction) and extremely anisotropic. Furthermore, we analysed the dielectric function and the absorption coefficient, and it is evident that the optical properties of the heterobilayers show a much larger spectral range compared with the isolated graphane, fhBN and silicane, especially the fhBN/silicane heterobilayer showing enhanced visible light absorption. These results offer new opportunities for developing electronic and opto-electronic devices based on the graphane/silicane heterobilayer and the fhBN/silicane heterobilayer. More importantly, our findings pave the way for investigating the effect of dihydrogen bondings not only on the electronic properties but also on the opto-electronic properties of the composite hydrogenated materials.