On the impact of adsorbed gas molecules on the anisotropic electro-optical properties of β12-borophene

We theoretically study the role of adsorbed gas molecules on the electronic and optical properties of monolayer β12-borophene with a,b,c,d,e atoms in its unit cell. We focus our attention on molecules NH3, NO, NO2, and CO, which provide additional states permitted by the host electrons. Utilizing the six-band tight-binding model based on an inversion symmetry (between a,e and b,d atoms) and the Kubo formalism, we survey the anisotropic electronic dispersion and the optical multi-interband spectrum produced by molecule-boron coupling. We consider the highest possibilities for the position of molecules on the boron atoms. For molecules on a,e atoms, the inherent metallic phase of β12-borophene becomes electron-doped semiconducting, while for molecules on b,d and c atoms, the metallic phase remains unchanged. For molecules on a,e and b,d atoms, we observe a redshift (blueshift) optical spectrum for longitudinal/transverse (Hall) component, while for molecules on c atoms, we find a redshift (blueshift) optical spectrum for longitudinal (transverse/Hall) component. We expect that this study provides useful information for engineering field-effect transistor-based gas sensors. © 2023 The Royal Society of Chemistry.