Boosting thermoelectric performance of PEDOT: PSS/Bi2Te3 hybrid films via structural and interfacial engineering

In this work, we synthesized poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) and PEDOT: PSS/Bi₂Te₃ hybrid composite film using a spin coating method. The maximum Seebeck coefficient (22 μVK⁻¹) and power factor (57.18 μWm^-1 K⁻² around 300 K) were achieved at 0.4 wt% Bi₂Te₃. The electrical conductivity (σ) reached a maximum of 1467 Scm⁻¹ at 300 K for 0.6 wt% Bi₂Te₃, which is more than three times higher than that of pure PEDOT: PSS. Two critical components contribute to the improved electrical transport performance, as identified by XRD, Raman spectroscopy, XPS, AFM, and SEM. First, the conductive polymer undergoes a structural transformation from a benzenoid to a quinoid configuration, enhancing conductivity. This transformation is due to the interaction between the π bonds of PEDOT: PSS and the Van der Waals forces between the tellurium (Te) atom layers of Bi₂Te₃. Second, the interfacial barrier between PEDOT: PSS and Bi₂Te₃ creates an energy-filtering effect that increases the Seebeck coefficient.