centrifuged twice, first for 10 minutes to remove any unexfoliated black phosphorus and then for 20 minutes at a higher speed to separate thick layers of phosphorene (5–12 layers) from NMP. The supernatant then is centrifuged again at higher speed for another 20 minutes to separate thinner layers of phosphorene (1–7 layers). The precipitate from centrifugation is then redispersed in water and washed several times by deionized water. Phosphorene/water solution is dropped onto silicon with a 280-nm SiO2 surface, where it is further dried under vacuum. NMP liquid exfoliation method was shown to yield phosphorene with controllable size and layer number, excellent water stability and in high yield. The disadvantage of the current methods includes long sonication time, high boiling point solvents, and low efficiency. Therefore, other physical methods for liquid exfoliation are still under development. A laser-assisted method developed by Zheng and co-workers showed a promising yield of up to 90% within 5 minutes. The laser photon interacts with the surface of bulk black phosphorus crystal, causing a plasma and solvent bubbles to weaken the interlayer interaction. Depending on the laser energy, solvent (ethanol, methanol, hexane, etc.) and irradiation time, the layer number and lateral size of the phosphorene were controlled. The high yield production of phosphorene has been demonstrated by many groups in solvents, but to realize the potential applications of this material, it is crucial to deposit these free-standing nanosheets in solvents systematically on substrates. H. Kaur et al. demonstrated the synthesis, interface-driven alignment and subsequent functional properties of few layer semiconducting phosphorene using Langmuir-Blodgett assembly. This is the first study which provides a straightforward and versatile solution towards the challenge of assembling nanosheets of phosphorene onto various supports and subsequently use these sheets in an electronic device. Therefore, wet assemblies techniques like Langmuir-Blodgett serves as a very valuable new entry point for the exploration of electronic as well as opto-electronic properties of phosphorene as well as other 2D layered inorganic materials. It is still a challenge to directly epitaxially grow 2D phosphorene because the stability of black phosphorene is highly sensitive to substrate, which is understanding by theoretical simulations. Properties Structure Phosphorene 2D materials are composed of individual layers held together by van der Waals forces in lieu of covalent or ionic bonds that are found in most materials. There are five electrons on 3p orbitals of phosphorus atom, thus, giving rise to sp3 hybridization of