Molybdenum diselenide belong to the large family of layered transition metal dichalcogenides. It consists of weakly coupled sandwiched layers i.e. Se - Mo - Se in which a Mo atom layer is enclosed within two Se layers. Most TMDCs form hexagonal layered structures. The repeating 2-D unit is a block formed by a plane of M atoms, in between two planes of chalcogen X. Interactions between atoms in a block are mainly covalent, while only saturated orbitals of the chalcogens are exposed to the exterior. Block-to-block interactions are 1 to 2 orders of magnitude weaker than within a block. This...