Enhancing Thermoelectric and Cooling Performance of Bi0.5Sb1.5Te3 through Ferroelectric Polarization in Flexible Ag/PZT/PVDF/Bi0.5Sb1.5Te3 Film

Bi2Te3-based thin films are gaining recognition for their remarkable room temperature thermoelectric performance. Beyond the conventional “process–composition–performance” paradigm, it is highly desirable to explore new methods to enhance their performance further. Here, we designed a sandwich-structured Ag/PZT/PVDF/Bi0.5Sb1.5Te3(BST) thin film device and effectively regulated the performance of the BST film by controlling the polarization state of the PZT/PVDF layers. Results indicate that polarization induces interlayer charge redistribution and charge transfer between PZT/PVDF and BST, thereby achieving the continuous modulation of the electrical transport characteristics of BST films. Finally, following polarization at a saturation voltage of 3 kV, the power factor of the BST film increased by 13% compared to the unpolarized condition, reaching 20.8 μW cm–1 K–2. Furthermore, a device with 7 pairs of P–N legs was fabricated, achieving a cooling temperature difference of 11.0 K and a net cooling temperature difference of 2.4 K at a current of 10 mA after the saturation polarization of the PZT/PVDF layer. This work reveals the critical effect of introducing ferroelectric layer polarization to achieve excellent thermoelectric performance of the BST film.