Flexible film and thermoelectric device of single-walled carbon nanotube@conductive metal-organic framework composite

Conducting metal-organic frameworks (MOFs) hold a great potential for many electronic applications because of their unique chemical and physical properties. Thermoelectric (TE) conversation based on conductive MOFs is the cutting-edge frontiers and remains great challenges, such as low electrical conductivity, rigidity, and difficulty to process. Here, a free-standing flexible film of the composite, where covalent bond grafting exists between single-walled carbon nanotubes (SWCNTs) and porous MOF (SWCNT@Ni-1,2,5,6,9,10-triphenylenehexathiol (THT)), is prepared by a convenient vacuum filtration method. The as-fabricated SWCNT@Ni-THT composite films exhibit good flexibility and p-type TE characteristics. An optimized power factor and a maximum figure of merit are ∼98.1 μW m^-1/K² and ∼0.037, respectively, for the composite film with 4 wt% SWCNT loading at 300 K. Furthermore, a flexible TE device connected by four rectangular films in series can generate an open-circuit voltage (V_OC) of ∼10.02 μV and the maximum power (P_max) of ∼1.59 μW at a temperature difference of 60 K. This work provides a novel way to prepare high-performance flexible films of MOF-based TE composites and demonstrates their potential applications in wearable electronics.