  We study collective plasmon excitations and screening of disordered single-
and bilayer black phosphorus beyond the low energy continuum approximation. The
dynamical polarizability of phosphorene is computed using a tight-binding model
that properly accounts for the band structure in a wide energy range.
Electron-electron interaction is considered within the Random Phase
Approximation. Damping of the plasmon modes due to different kinds of disorder,
such as resonant scatterers and long-range disorder potentials, is analyzed. We
further show that an electric field applied perpendicular to bilayer
phosphorene can be used to tune the dispersion of the plasmon modes. For
sufficiently large electric field, the bilayer BP enters in a topological phase
with a characteristic plasmon spectrum, which is gaped in the armchair
direction.
