Poly(phthalazinone ether ketone) – Poly(3,4-ethylenedioxythiophene) fiber for thermoelectric and hydroelectric energy harvesting

A kind of thermoelectric and hydroelectric energy harvesting fiber made of poly(phthalazinone ether ketone) (PPEK) and poly(3,4-ethylenedioxythiophene) (PEDOT) was prepared by wet-spinning PPEK fiber and in-situ polymerization of PEDOT on PPEK fiber. The crystallinity of the PEDOT component in PPEK-PEDOT fibers increased from 28.2 % to 42.1 % with the molar ratio of 3,4-ethoxylenedioxythiophene (EDOT) and FeCl3 increased from 0.75:1 to 3:1, and the electrical conductivity of PPEK-PEDOT fiber increase from around 0.3 × 10-3 S cm−1 to almost 25.4 × 10-3 S cm−1. Benefiting from the high crystallinity, good electrical conductivity of PPEK-PEDOT fibers and the porous structure inherited from PPEK fibers, PPEK-PEDOT fibers have good thermoelectric and hydroelectric energy harvesting capabilities. PPEK-PEDOT fiber has a tree-like structure with a radial distribution of pores on the fiber cross-section, forming pore channels along the fiber axis direction, which enhanced the hydroelectric energy harvesting properties. PPEK-0.66PEDOT fiber that treated by 2wt% poly(ethylenimine) (PEI) ethanol solution would generate about 1.6 mV thermoelectric voltage with only 2 cm fiber length under the temperature gradient of 21 ℃ and produce ∼ 260 mV hydroelectric voltage under 99 % humidity at 30 ℃. As a whole, the compact and flexible PPEK-PEDOT fiber prepared in this work showed great potential in the field of thermoelectric and hydroelectric energy generation for wearable electronic devices.