Materials design strategies for green thermoelectric generators enabling sustainable and scalable energy harvesting.

Thermoelectric generators (TEGs) harvest low-grade heat without moving parts and can be integrated into compact, flexible, or distributed systems. Progress in this field is typically measured through figure of merit, ZT, and the power factor, yet materials with high ZT often depend on scarce elements, toxic precursors, high-temperature processing, or difficult end-of-life recovery-considerations that matter for technologies intended to support sustainable energy systems. This perspective examines green thermoelectric design as a coupled materials, process, device, and life cycle problem, considering how aqueous processing, bio-assisted synthesis, hydrothermal methods, electrochemical deposition, and printable processing shape microstructure, defect chemistry, and charge-heat transport in conductive polymers, carbon nanotube hybrids, biomass-derived carbons, recycled inorganic compounds, and ionic thermoelectric systems. We propose a design framework that combines material abundance, process energy, solvent and waste burden, device lifetime, manufacturability, and circularity, and identify where environmentally responsible TEGs can deliver useful power with lower total burden.