We are interested in photo-physics in nano, molecular, and hybrid semiconductors and interfaces. We focus on dynamics of quasiparticles (excitons, polarons, polaritons, etc.) and their many-body interactions. These interactions are important to a range of optoelectronic processes, such as solar energy conversion, light emission, and polariton condensation. We employ state-of-the-art experimental techniques, including, among others, time-resolved photoemission spectroscopy, femtosecond nonlinear optical spectroscopies, transient absorption and emission spectroscopies, and two-dimensional spectroscopies. As examples, recent discoveries in our lab revealed how dynamic screening and large polaron formation can make lead halide perovskite defect tolerant, how excitons at van der Waals 2D semiconductor interfaces undergo phase transitions, and how magnetic order couple to excitons in 2D magnetic semiconductors.