The ability to precisely control the light-matter interaction in low dimensional materials (0D, 1D, 2D) unveils a rich playground for the exploration of novel optoelectronic properties. From a fundamental point of view, the enhanced Coulomb interactions due to the low-dimensional confinement endow carrier–carrier interactions, predicted to generate exotic effects such as exciton complexes, coherent optical Stark effect, Mott transitions, bandgap renormalization, and lasing or amplified spontaneous emission (ASE). In this talk, I will present the fascinating photophysical phenomena that arise from two such emerging quantum confined semiconductors: metal halide perovskite nanocrystals (MHPN) and atomically thin transition metal dichalcogenides (TMDCs). In the first part of my talk, I will explore a new design strategy of facet engineering to reduce the gain threshold of ASE, a crucial advancement in the pursuit of future on-chip microchip lasers. The later part of the talk concentrates on manipulating many-body interactions through dynamic exploiting of dielectric environment to control the optical and electronic properties in atomically thin TMDCs. Join us in exploring the fascinating world of quantum confinement.