Abstract: Mono- or few-layers semiconducting two-dimensional materials (S2DM) exhibit exciting optical, electrical, magnetic, and catalytic properties. Due to these properties, S2DM have potential applications in ultrathin electronics, photonics, transistors, light emitting diodes, touchscreens, energy storage devices, and catalysis. The exciting properties of the S2DM emerge from the formation of localized excitons of a large exciton binding energy when photoexcited. Additionally, the strong spin-orbital coupling (SOC) inside the individual S2DM sheet and the breaking of symmetry inversion induced the splitting of the valence band at the K valley of the Brillouin zone into A and B peaks. The band gap values and band edge positions of S2DM depend greatly of the strength of SOC. This presentation focus on modifying the band gap of S2DM by different techniques including: integrating the S2DM with plasmonic nanoparticles of strong electromagnetic field that alters the spin orbital coupling, thus change the energy of the valence and conduction bands, applying strain that disturbs the bond lengths and the SOC, electron injection, which increase the electron density on the conduction band of S2DM and induce band gap renormalization, and change the dielectric function of the surrounding medium.