  Black Phosphorus (BP) is an excellent material for post graphene era due to
its layer dependent band gap, high mobility and high Ion/Ioff. However, its
poor stability in ambient poses a great challenge in its practical and
long-term usage. Optical visualization of oxidized BP is the key and foremost
step for its successful passivation from the ambience. Here, we have done a
systematic study of the oxidation of BP and developed a technique to optically
identify the oxidation of BP using Liquid Crystal (LC). Interestingly we found
that rapid oxidation of thin layers of BP makes them disappear and can be
envisaged by using the alignment of LC. The molecular dynamics simulations also
proved the preferential alignment of LC on oxidized BP. We believe that this
simple technique will be effective in passivation efforts of BP and will enable
it for exploitation of its properties in the field of electronics.
