Electronic structure and conductivity in functionalized multilayer black phosphorene

Phosphorene and its components are highly reactive to oxygen when exposed to ambient conditions due to the presence of lone pairs of electrons on phosphorus atoms. Functionalization serves as a solution to prevent the chemical degradation of these materials. In this paper, we investigate the impact of relatively strong covalent or noncovalent functionalization on phosphorene [monolayer black phosphorus (BP)], few-layer BP, and bulk BP. We use an effective tight-binding Hamiltonian that corresponds to one orbital per site, wherein covalent functionalization is simulated by atomic vacancies, and noncovalent functionalization is simulated by Anderson disorder. We demonstrate that these two types of functionalization act differently on the electronic structure and quantum diffusion, particularly affecting the gap and mobility characteristics, especially with a high degree of functionalization. However, we also show that the mobility gap is not significantly modified by the two types of defects. We also analyze the electron-hole asymmetry that is more important for multilayer and bulk BP.