Recent progress in tuning polymer oriented microstructures for enhanced thermoelectric performance

In recent years, the research of conjugated polymer-based thermoelectric (TE) materials has experienced exponential growth due to their diverse advantages and promising application potentials in internet-of-things, medical/health monitoring, and flexible and wearable electronics, etc. Oriented microstructure is undoubtedly vital governing polymer macroscopic performances, including mechanical, thermal and TE properties. Regretfully, the corresponding review or summary of the relation between oriented microstructure and TE performance is scarce for conjugated polymers. Here, the recent progress of orienting conjugated polymers in TE applications is reviewed. First, typical methods to achieve the oriented microstructure, including both long-range in-plane orientation and local ordered structure, are introduced. Then, to deepen a fundamental understanding of the relationship between oriented structure and TE performance, the underlying mechanism are discussed by taking insights from charge and phonon transports. Finally, the main challenges and the future prospects are outlooked.