Enhanced Thermoelectric Performance of Flexible SWCNT/CuS/PVP Composites at High Temperature

Single-walled carbon nanotubes (SWCNTs) are promising candidates for constructing flexible thermoelectric devices, but the performance of CNT-based thermoelectric materials at high temperatures still requires further enhancement. This work proposes an interfacial engineering strategy for compositing CuS, polyvinylpyrrolidone (PVP), and SWCNTs, in which PVP stabilized and encapsulated CuS nanoparticles, enabling their uniform incorporation into the SWCNT network. p-Type doping and reconstruction of the interfacial electronic environment were subsequently achieved through acid treatment, which enhances interfacial polarization and charge redistribution, strengthening interfacial coupling while preserving the conductive framework of SWCNTs. Benefiting from optimized interfacial electron transport, the CuS/PVP/SWCNT composite film achieves a power factor of 206.13 ± 8.72 μW m–1 K–2 at room temperature and further affords a maximum Seebeck coefficient of about 51.22 μV K–1 and a power factor of 270.44 μW m–1 K–2 at 489 K, demonstrating potential for thermoelectric applications at medium-to-high temperatures. A flexible thermoelectric generator with seven pairs of p-n legs was further constructed to validate practicality, achieving a maximum output power of 2.09 μW at ΔT = 160 K. Concurrently, a photothermoelectric-coupled generator was developed, demonstrating the system’s future applications in multifunctional energy conversion integration. This design approach significantly enhances the thermoelectric and device output performance of the CNT/CuS/polymer composite system through interface coupling and polarization effect regulation, providing a viable pathway for multifunctional energy conversion in wearable and miniaturized energy harvesting applications.