Mechanical Energy Harvesting and Specific Potential Distribution of a Flexible Piezoelectric Nanogenerator Based on 2-D BaTiO₃-Oriented Polycrystals

The development of a flexible wearable piezoelectric power device has recently caught extensive attention, especially in making inorganic piezoelectric ceramics into polymers from a composite with excellent piezoelectric response. As inorganic piezoelectric fillers, an oriented polycrystal can improve the mechanical energy efficiency of piezoelectric nanogenerators. Herein, the two-dimensional BaTiO3-oriented polycrystals are prepared via a two-step hydrothermal process based on a topochemical conversion mechanism. Additionally, a high-performance piezoelectric nanogenerator was successfully fabricated using the polydimethylsiloxane (PDMS) polymer and BaTiO3-oriented polycrystals. The flexible piezoelectric nanogenerator with 30 wt % BaTiO3 exhibited optimal piezoelectric performance, with an output open-circuit voltage of 13.0 V and a short-circuit current of 200 nA under a periodic mechanical bend-release mode. More importantly, an effective power of approximately 2.6 μW was achieved at a low load resistance of 35 Mω, suggesting a large potential for applications of electronic skins and self-powered devices. The device efficiently harvests biomechanical energy from human activities and exhibits stable output voltage and current of approximately 8 V and 150 nA, respectfully, demonstrating great promise as a wearable energy harvester. This work demonstrates that oriented nanocrystals in combination with a polymer matrix can lead to the design of high-efficiency piezoelectric nanogenerators that are particularly useful in artificial intelligence, soft robotics, and biomedical devices.