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Barium titanate/polyvinylidene fluoride- (BT/PVDF-) based nanocomposite film exhibits excellent energy storage and mechanical properties and can be used as flexible electronic components.

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 BaTiO 3 -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 BaTiO 3oriented polycrystals. The flexible piezoelectric nanogenerator with 30 wt % BaTiO 3 exhibited optimal piezoelectric performance, with an output opencircuit 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.

KNbO 3 (KN) piezoelectric polycrystals were prepared by a two-step solvothermal reaction process with the managed organic solvents as reaction mediums at a low temperature for a short time. In the solvothermal reaction system, the formation mechanism of polycrystalline KN is mainly the dissolution−deposition mechanism. The influences of alkalinity, viscosity, and the polarity for reaction mediums on the formation of the niobates were investigated. The chemical reaction mechanisms of niobate products and formation mechanism of niobate crystals from the precursor were clarified. The regulating and controlling mechanism of the phase compositions, the morphologies, and the lattice constants for the niobates obtained in varied reaction mediums were revealed. The obtained KN piezoelectric polycrystals are constructed from oriented KN nanocrystals. Piezoelectric hysteresis loops of cuboid KN polycrystals were detected for the first time. A prepared cuboid KN polycrystal shows an average d 33 * value of 32 pm/V. The study provides a strategy for the development of oriented KN piezoelectric materials to apply the orientation engineering.

The interface coupling ability of inorganic and organic matter can affect the energy storage density, charge–discharge efficiency, dielectric loss, and many other parameters that define the energy storage performance. Therefore,...