  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 defect. We also analyze the electron-hole asymmetry that is more
important for multilayer and bulk BP.
