A New Era in Sustainability: Te- and Pb-Free Thermoelectrics

Nearly two-thirds of global energy is lost as waste heat. Thermoelectric materials enable the direct conversion of heat into electricity, offering a promising recovery strategy. However, many high-performance systems rely on toxic or scarce elements such as Pb and Te, limiting sustainability. This review compares transport mechanisms in bulk and thin-film thermoelectrics, highlights environmentally benign material alternatives and fabrication routes, and discusses key challenges and future opportunities for sustainable energy applications. To provide a comprehensive overview of tellurium- and Pb-free bulk thermoelectrics, recent developments are summarized in a comprehensive table detailing material composition, peak zT values, temperature differences (ΔK), efficiencies (η), power output (Pout) (or maximum power density (Pmax)), and device geometries.