Vertically Aligned, Highly Ordered BiFeO₃-BaTiO₃ Micropillars Supported by a Flexible P(VDF-TrFE) Layer for Harvesting Mechanical Energy and Sensing Applications

Flexible piezoelectric materials have aroused significant interest in recent years due to their promising applications in portable and wearable electronic devices. However, developing high-performance flexible piezoelectric functional layers with a controllable morphology through an economical and simple approach remains a challenge. In this paper, highly ordered 0.7BiFeO3-0.3BaTiO3 (BFO-BTO) micropillars were prepared in a controllable manner using a facile and cost-effective method based on commercial anodized aluminum oxide (AAO) templates. P(VDF-TrFE) was elected as the flexible carrier platform. Finite element simulation revealed that the incorporation of regular micropillars significantly enhances the strain distribution in the composite piezoelectric films, thereby increasing the piezopotential. Among the films with varying micropillar heights, the 1.5 μm BFO-BTO/P(VDF-TrFE) demonstrated an enhanced β-phase content and a higher figure of merit (FOM33). A prototype piezoelectric device constructed with this functional layer exhibited exceptional performance, including high force sensitivity (4.69 V N-1), high output voltage (3.54 V), and superior mechanical stability (2000 cycles). Owing to these properties, the device holds promise in mechanical energy harvesting and real-time monitoring of human body motions. The proposed AAO template-assisted fabrication strategy offers a paradigm for designing high-performance flexible piezoelectric components for energy harvesting and sensing applications.