This talk will present recent results from a number of research groups within the Next Generation for Materials by Design (CNGMD) Energy Frontier Research Center (EFRC), a multi-institution funded by DOE. Our overall goal is to design, discover and synthesize new energy-relevant functional materials, including non-equilibrium structures, with targeted functionalities by integrating theory, high-throughput computation, synthesis, and characterization. Our focus is on semiconductor materials for renewable energy and energy efficiency applications including solar energy conversion, solid-state lighting, solar fuel production and piezoelectrics. A primary goal is to incorporate functional metastable materials into materials by design and establish ranges for materials metastability as a function of the chemistry, energetics, and structure. We are examining three classes of metastable systems: defects, polymorphs, and solid solutions (alloys). We are also trying to develop a systematic theory-driven approach to guide the synthesis of new materials—including metastable systems—by coupling theory and state-of-the-art in-situ characterization to probe materials growth pathways. Highlights from our research will be presented including: Pnictide Search where we are exploring new metal nitrides to discover new functional semiconductor materials; Polymorphs and Synthesizability where we are understanding energy landscapes and identifying synthetic pathways for specific polymorphs focusing on Mn and Ti oxides; Chalcogenide Alloys where we predict and guide the synthesis of new functional semiconductor alloy materials; and Perovskite-Inspired Materials Search which designs new materials based on the electronic features of defect tolerance and long carrier lifetimes observed in hybrid organic-inorganic halide perovskites.