Quinoidal conjugated materials: Design strategies and thermoelectric applications

The growing demand for waste heat energy recovery from electronic devices, solar energy, and industrial production has led to increased attention on thermoelectric materials. In the past decades, significant progress has been achieved in inorganic thermoelectric materials. Moreover, flexible, lightweight, and bio-friendly organic thermoelectric (OTE) materials have emerged as promising candidates for thermoelectric devices. In particular, quinoidal conjugated small molecules and polymers with high mobility are suitable for thermoelectric conversion. Such kind of materials have gained increasing research interest due to their unique structural features and characteristics of polarons’ delocalization. Concurrently, quinoidal materials with high mobility and conductivity have been developed, and their use for thermoelectric conversion has been increasingly reported. This perspective summarizes the recent advancements in the design and synthesis of quinoidal conjugated small molecules and polymers, their advantages for thermoelectric conversion, and the latest reports on their charge carrier transport mechanisms. Moreover, to further enhance the TE performances of quinoidal materials, the existing challenges are discussed and the future developments are also outlooked.