Realizing high thermoelectric performance flexible free-standing PEDOT:PSS/Bi_0.5Sb_1.5Te₃ composite films for power generation

Flexible thermoelectrics provide a distinct solution for developing sustainable and portable power supplies. Inorganic/organic material compositing is an effective strategy to induce a significant enhancement of thermoelectric (TE) performance. However, the poor electrical performance of inorganic/organic material is attributed to the poor carrier transport between organic/inorganic interfaces induced by the low contribution of composited inorganic materials. Herein, we prepared a high room temperature figure-of-merit (ZT) value of ~ 0.19 and high bending resistance (surviving 1200 bending cycles at the bending radius of 16.5 mm) of p-type poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)/Bi_0.5Sb_1.5Te₃ free-standing composite film via a facile vacuum-assisted filtration approach. Compositing Bi_0.5Sb_1.5Te₃ nano-spherical particles into PEDOT:PSS results in the optimized interfacial contact and carrier concentration, leading to a high Seebeck coefficient of ~ 43.79 μV·K⁻¹. Accordingly, a high-power factor of ~ 1.52 μW·cm⁻¹·K⁻² is achieved in the PEDOT:PSS/Bi_0.5Sb_1.5Te₃ composite film at room temperature. In addition, the PEDOT:PSS/Bi_0.5Sb_1.5Te₃ interfaces with phase boundaries, nanograins and point defects could further decrease the thermal conductivity to ~ 0.20 W·m⁻¹·K⁻¹, leading to a high ZT value. Furthermore, a 6-leg free-standing film device was assembled, which provided an output power of 44.94 nW. This study demonstrates that free-standing organic/inorganic composite films are effective power sources for wearable electronic products.