A Highly Electrostrictive Salt Cocrystal and the Piezoelectric Nanogenerator Application of Its 3D-Printed Polymer Composite

Advancing Nanogenerators: The Role of 3D-Printed Nanocomposites in Energy Harvesting

Nanogenerators have garnered significant scholarly interest as a groundbreaking approach to energy harvesting, encompassing applications in self-sustaining electronics, biomedical devices, and environmental monitoring. The rise of additive manufacturing has fundamentally transformed the production processes of nanocomposites, allowing for the detailed design and refinement of materials aimed at optimizing energy generation. This review presents a comprehensive analysis of 3D-printed nanocomposites in the context of nanogenerator applications. By employing layer-by-layer deposition, multi-material integration, and custom microstructural architectures, 3D-printed nanocomposites exhibit improved mechanical properties, superior energy conversion efficiency, and increased structural complexity when compared to their conventionally manufactured counterparts. Polymers, particularly those with inherent dielectric, piezoelectric, or triboelectric characteristics, serve as critical functional matrices in these composites, offering mechanical flexibility, processability, and compatibility with diverse nanoparticles. In particular, the careful regulation of the nanoparticle distribution in 3D printing significantly enhances piezoelectric and triboelectric functionalities, resulting in a higher energy output and greater consistency. Recent investigations into three-dimensional-printed nanogenerators reveal extraordinary outputs, encompassing peak voltages of as much as 120 V for BaTiO3-PVDF composites, energy densities surpassing 3.5 mJ/cm2, and effective d33 values attaining 35 pC/N, thereby emphasizing the transformative influence of additive manufacturing on the performance of energy harvesting. Furthermore, the scalability and cost-effectiveness inherent in additive manufacturing provide substantial benefits by reducing material waste and streamlining multi-phase processing. Nonetheless, despite these advantages, challenges such as environmental resilience, long-term durability, and the fine-tuning of printing parameters remain critical hurdles for widespread adoption. This assessment highlights the transformative potential of 3D printing in advancing nanogenerator technology and offers valuable insights into future research directions for developing high-efficiency, sustainable, and scalable energy-harvesting systems.

A Ferroelastic Salt Cocrystal with Ultraviolet Emission

The coexistence and coupling of photoluminescence and ferroelasticity in a single matter are vitally important for developing multifunctional materials and devices. However, the effective construction of ferroelastics with efficient photoluminescence, especially in the ultraviolet range, is a great challenge. In this work, a salt cocrystal, (DPA)(DPAH)PF6 (DPA = diphenylamine, DPAH = diphenylamine cation), with ultraviolet emission and ferroelasticity was reported by introducing the anion group PF6- in the parent DPA crystal. Besides, the thermally triggered order-disorder transition of PF6- groups leads to a ferroelastic phase transition at ∼340 K with the Aizu notation of 2/mF1̅. In addition, (DPA)(DPAH)PF6 displays a bright ultraviolet emission at 392 nm with a photoluminescence quantum yield of 49.4%. This work presents a strategy to achieve ultraviolet (UV)-emissive ferroelastic based on the luminescent organic crystal, which not only extends the luminescence of ferroelastic to the UV region but also paves a new way for the development of multifunctional ferroelastic materials and devices.

Metal-free small molecule-based piezoelectric energy harvesters

Organic and metal-free molecules with piezoelectric and ferroelectric properties have gained wide interest for their applications in the domain of mechanical energy harvesting due to their desirable properties such as light weight, thermal stability, mechanical flexibility, feasibility to achieve high Curie temperatures, and ease of synthesis. However, the understanding and design of these materials for piezoelectric energy harvesting applications is still in its early stages. This review paper presents a comprehensive overview of the fundamental characterization of piezoelectricity for a range of organic ferro- and piezoelectric materials and their composites. It also discusses the limitations of traditional piezoelectric materials and highlights the advantages of organic materials in this area in the introduction part. In addition, the paper provides a detailed description of peptide-based and other biomolecular piezoelectric materials as a bio-friendly alternative to current materials. This perspective aims to guide researchers in designing functional organic materials and composites for practical mechanical energy harvesting applications and to highlight current limitations and future perspectives in this emerging area of research.