Novel construction of P- and N-type thermoelectric materials with different crystalline Cu2O-doped SWCNTs and their thermoelectric applications

Recent industrial advancements have accelerated the development of thermoelectric devices for waste heat recovery and energy conversion. The fabrication of both n-type and p-type thermoelectric materials from the same substance has attracted broad research interest. In this study, p-type and n-type thermoelectric films were prepared using single-walled carbon nanotubes (SWCNTs) and Cu 2 O, with only minor differences in processing and composition. The two types of films exhibited distinct properties, which correlated with different crystal morphologies of Cu₂O: a rice-like microstructure in the p-type material and spherical microstructure in the n-type material. After p-type doping with Cu 2 O, the optimal Seebeck coefficient increased from 16 μV·K −1 to 41.2 μV·K −1 , while the electrical conductivity decreased from 67,891 S·m −1 to 2338.5 S·m −1 . The p-type SWCNT/Cu 2 O film achieved a maximum ZT value of 0.018, approximately 60 times higher than that of pure SWCNTs. For the n-type doped film, the Seebeck coefficient changed from 16 μV·K −1 to −17.6 μV·K −1 , and the electrical conductivity decreased to 27,828.5 S·m −1 , yielding a maximum ZT of 0.012—about 40 times higher than pure SWCNTs. A device consisting of six pairs of p-type and n-type films generated a voltage of up to 34.56 mV at a temperature difference of 100 K, demonstrating excellent thermoelectric performance. Both composite films also showed outstanding electrothermal properties: the p-type film reached 295 °C at 7 V with stable heating at 6 V, while the n-type film reached 335 °C at 6 V and exhibited good stability at 3.5 V. This work offers a simple and effective strategy for designing high-performance p-type and n-type thermoelectric materials from the same base system.