High Thermoelectric Performance Related to PVDF Ferroelectric Domains in P‐Type Flexible PVDF‐Bi_0.5Sb_1.5Te₃ Composite Film

Abstract There is increasing demand to power Internet of Things devices using ambient energy sources. Flexible, low‐temperature, organic/inorganic thermoelectric devices are a breakthrough next‐generation approach to meet this challenge. However, these systems suffer from poor performance and expensive processing preventing wide application of the technology. In this study, by combining a ferroelectric polymer (Polyvinylidene fluoride (PVDF, β phase)) with p‐type Bi_0.5Sb_1.5Te₃ (BST) a thermoelectric composite film with maximum is produced power factor. Energy filter from ferroelectric‐thermoelectric junction also leads to high Seebeck voltage ≈242 µV K⁻¹. For the first time, compelling evidence is provided that the dipole of a ferroelectric material is helping decouple electron transport related to carrier mobility and the Seebeck coefficient, to provide 5× or more improvement in thermoelectric power factor. The best composition, PVDF/BST film with BST 95 wt.% has a power factor of 712 µW•m⁻¹ K⁻². A thermoelectric generator fabricated from a PVDF/BST film demonstrated P_max^T 12.02 µW and P_density 40.8 W m⁻² under 50 K temperature difference. This development also provides a new insight into a physical technique, applicable to both flexible and non‐flexible thermoelectrics, to obtain comprehensive thermoelectric performance.