Our work focuses on the development of new, sustainable materials for energy and optoelectronic applications including photovoltaic, water-splitting, and light-emitting devices. Currently, we investigate two materials classes for use in such devices: Halide-based perovskites and complex chalcogenide semiconductors. Perovskites and chalcogenides both hold the potential for low-cost and sustainable next-generation devices. Within each of these focal areas, we work to design novel materials, as well as to understand the fundamental chemical, structural, optical, and electronic properties underlying the semiconductors. Once interesting systems are identified, we also develop appropriate film/crystal growth techniques and build device structures around the new materials with a target of outstanding device performance.