Emerging Hot Issues in Organic Thermoelectrics

The rapid growth of modern industry produces vast amounts of waste heat that remain largely underutilized, causing energy inefficiency and environmental concerns. Thermoelectric (TE) technology, enabling direct heat-to-electricity conversion, offers a sustainable route for harvesting low-grade thermal energy. Organic semiconducting and conducting materials have recently emerged as attractive TE alternatives to inorganics, owing to their lightweight, chemical tunability, mechanical flexibility, and compatibility with scalable solution processing. Their inherently low thermal conductivity further boosts energy conversion efficiency, while stability up to ∼200 °C broadens their potential for low-temperature applications. Despite these advantages, several key challenges remain. To address these issues, this mini-review highlights three emerging research directions: (i) photothermoelectric conversion, (ii) dopant-free diradicaloid systems with intrinsic stability, and (iii) mixed ionic–electronic conduction for improved thermovoltage. Collectively, these strategies provide insights and guide the development of next-generation organic TE technologies.