High-performance flexible piezoelectric film through in situ engineered P(VDF-TrFE)/BaTiO3 on titanium foils

Flexible piezoelectric films represent a groundbreaking advancement for wearable energy harvesting and bioelectronics, where mechanical adaptability and efficient electromechanical conversion are equally crucial. However, the persistent incompatibility between high piezoelectric coefficients and structural pliability creates a critical performance ceiling that undermines device reliability in dynamic operating environments. Here, we report an in situ interface engineering strategy to fabricate high-performance flexible piezoelectric films directly on Ti foils through combining hydrothermal synthesis of BaTiO 3 films with infiltration of P(VDF-TrFE). The flexible P(VDF-TrFE)/BaTiO 3 film with spatially interlocked heterostructure exhibits an excellent piezoelectric coefficient d 33 of ~264 pC N −1 , representing an enhanced remnant polarization of 21.4 μC cm −2 and a reduced coercive field of 220 kV cm −1 . The as-prepared piezoelectric film assembled on the Ti foil substrates demonstrates long-lasting flexibility, retaining an output voltage of about 5 V after 5000 bending cycles. The exceptional performance originates from the improved polarization through the stabilized BTO nanodomain synthesized by the in situ hydrothermal process. Furthermore, the spatially interlocked architecture redistributes polarized charges, thereby mitigating polarization degradation induced by microscale defects. This study pioneers a new paradigm for developing high-performance flexible piezoelectric film, and the scalable process can be potentially applied to wearable applications.