Heterogeneous Integration of PZT Thin Films on Flexible Polyimide Substrates via a ZnO Release Process for Energy Harvesting

Inorganic piezoelectric films typically require high crystallization temperatures, making integration with flexible polymer substrates challenging. In this work, we develop a film transfer technique using a zinc oxide (ZnO) sacrificial layer to address this issue. By selectively etching the ZnO interlayer, we transfer large-area Nb 0.02 -Pb(Zr 0.6 Ti 0.4 )O 3 (PZT) films onto flexible substrates, enabling the fabrication of a high-performance flexible piezoelectric energy harvester (FPEH). The resulting 2-μm-thick PZT film exhibits a high piezoelectric coefficient ( d 33 ≈ 251 pm/V) and excellent dielectric properties. The FPEH produces output powers of 0.13 μW during periodic bending and 0.31 μW under applied pressure. Additionally, the device functions as a sensitive strain sensor capable of detecting human vocal signals during speech. This transfer approach facilitates the integration of high-efficiency piezoelectric materials into flexible electronics and self-powered systems.