Light-matter interaction is at the heart of most optical phenomena that we are familiar with such as absorption, emission and scattering. We normally treat these by assuming that light does not significantly modify the underlying electronic states of the material it interacts with. The extreme case where light-matter interaction is so strong that this assumption fails has been coined the strong-coupling regime. In this regime, new half-light, half-matter quasiparticles called polaritons emerge. In the first part of the talk, we will focus on progress in harnessing light-matter coupling to modify processes that are relevant to improving optoelectronic devices. In the second part of the talk, we will discuss efforts to use 2D semiconductors for mid-infrared light-emission and describe light-emitting devices based on black phosphorus and black phosphorus alloys as approaches towards scaling the fabrication of such devices over large areas.