As aggressive decarbonization goals are set around the world it is important that we maintain a pipeline of high-performance photovoltaic (PV) materials, both well-known and novel, to meet growing demand. Thin-film compound semiconductor PV materials are well suited to help meet this demand as they continue to demonstrate their potential for generating sustainable and cost-efficient electrical energy. Both fundamental understanding and processing techniques have enabled advantages in manufacturing and materials costs, with power conversion efficiencies now above 20%, but cutting-edge materials research is still needed for these technologies to flourish. Emerging areas of research include the materials science of degradation, understanding the roles of passivation and compensation, reducing interface and grain boundary recombination, tandem, bifacial, and semitransparent devices. The symposium will focus on the science and technology of polycrystalline films, single crystal model systems, defects, interfaces, the interplay of materials and band structure, characterization methods, modeling, scaling and advanced manufacturing in thin-film compound semiconductor photovoltaics. Relevant materials include those based on chalcogenide semiconductors such as copper indium gallium (di)selenide (CIGS) and a cadmium telluride (CdTe) as well as the associated alloys, heterojunction partner materials, and buffer layers. Novel absorber materials, heterojunction partner layers, and (semi-) transparent absorber layers are also of high interest.