Unlike three-dimensional materials, screening of the interaction across quasiparticles in atomically thin materials can significantly alter their electronic and phononic properties. Earlier studies have demonstrated that dielectric screening can modify material parameters, including electronic mobility, conductivity, Raman modes, Seebeck coefficient, and photoluminescence, in semiconducting two-dimensional (2D) materials. In this talk, I will discuss our efforts on finding novel two-dimensional materials with phase transitions via interlayer space modification and how screening modification via substrate engineering can be used in conjunction with scanning photocurrent microscopy to investigate the fundamental properties of 2D materials, such as photoresponse mechanisms. Moreover, I will illustrate how metals can be used to achieve screening, despite the odds, at the ultimate proximity to control the excitonic light emission from semiconducting 2D materials. Ultimately, I will attempt to demonstrate how screening effects can be leveraged to enhance various electronic and optical properties of two-dimensional materials.