Electrospun biomass polyethylene furanoate nonwoven substrates for flexible thermoelectric generators

Polyethylene furanoate (PEF) stands out as a highly promising biopolymer, characterized by its lower melting point and higher flexibility than those of polyethylene terephthalate (PET). Moreover, the enhanced functionality of PEF broadens its potential applications across various domains. Herein, the synergistic integration of PEF with a polymer thermoelectric layer is explored via the formulation of advanced environmentally sustainable materials for prospective utilization in flexible thermoelectric generators for the emerging field of green energy. The fabrication process involves the creation of PEF nonwoven via the electrospinning technique, thereby endowing the PEF with considerable stretchability. Concurrently, the polymer thermoelectric layer is developed by blending dimethyl sulfoxide (DMSO) and D-sorbitol in a poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) solution, followed by drop-casting PEDOT:PSS onto glass substrates. Subsequently, free-standing PEDOT:PSS films are transposed onto PEF nonwoven substrates with a power factor of 17.84 μW m⁻1 K⁻2 and an elongation of 24 % at breaking point. The intimate compatibility between the PEDOT:PSS film and PEF nonwoven substrate is demonstrated by the cyclic bending test results, wherein over 90 % of the original conductivity is maintained after 1000 cycles, thereby highlighting the potential of the developed device as a thermoelectric generator. Finally, a 12-leg thermoelectric generator is fabricated, yielding an output voltage of 3.63 mV and an output power of 34.52 nW under a temperature gradient of 32.3 K.