Thermoelectric Performance Boost of n-Type Carbonized Polydopamine through Nanoarchitectonics with Synergistic Catalysis and Coordination Strategy

The lagging development of n-type organic thermoelectric materials based on a conjugated polymer drastically curtails the advancement of high-performance flexible thermoelectric devices, which is largely attributed to the lack of effective doping approaches. Bioinspired polydopamine (PDA) materials possess abundant functional groups that provide a platform for doping and other functional processes. In this study, we developed a strategy that synergistically integrates calcium (Ca) coordination and iron (Fe) nanoparticle catalysis during the carbonization process of PDA to enhance the thermoelectric performance of n-type carbonized-PDA (cPDA). Fe nanoparticles catalyzed the growth of graphite nanocrystals in cPDA during the carbonization process, resulting in a conductivity enhancement from 6.9 × 104 to 3.31 × 105 S m−1. Meanwhile, Ca coordination introduced a lower energy level of the lowest-unoccupied molecular orbital (LUMO) orbit, selectively supplying high-energy electrons to boost the Seebeck coefficient from −4.22 to −10.47 μV K−1. As a result, the power factor (PF) increased nearly 30 times, and a PF value of 36.3 μW m−1 K−2 was recorded. Furthermore, the improved cPDA materials are thermally stable up to 500 °C. This work reveals the potential of cPDA in n-type thermoelectric applications and provides a route for the development of high-performance flexible thermoelectric materials.