Innovative structure for energy harvesting: Layered PVDF/TPU nanofibers with synergistic piezoelectric, dielectric, and ferroelectric enhancement

The fabrication process is critical for optimizing the piezoelectricity of PVDF/TPU nanofibers. This work illustrates the merits of layer-by-layer (LBL) electrospinning in optimizing the piezoelectric behavior of PVDF/TPU nanofibers for energy harvesting. In comparison with solution blending (SB), LBL electrospinning promotes molecular orientation and β-phase crystallization, which contributes to improved piezoelectric activity. The 8 LBL sample showed the optimal mechanical and electrical characteristics, with the highest output voltage (116.27 ± 5.4 V/mm) at applied force 0.5 N, along with piezoelectric coefficient (d₃₃ = 38.52 ± 0.92 pC/N), the output current (I p–p = 1.6 μA), and surface charge density (SCD = 0.57 μC/m²). Mechanical characterization revealed that 8 LBL withstood high strains due to slippage of fibers, and their failure was observed at higher stackings (10 and 12 LBL), reducing their efficiency. The dielectric constant increased with stacking from 14.7 ± 0.85 at 6 LBL to 28.9 ± 1.93 at 12 LBL due to the interfacial polarization. While ferroelectric characterization pointed towards the 8 LBL as the optimum architecture with a coercive field of 562 kV/mm and energy storage efficiency of 67.5 %. LBL stacking of nanofibers leads to synergistic triboelectric–piezoelectric coupling along with an optimum mechanical design. The 8 LBL sample exhibited the best properties among all architectures and points towards the potential of LBL electrospun PVDF/TPU nanofibers in high-efficiency flexible and self-powered electronics. Compared with recently reported PVDF/TPU and hybrid PVDF systems, which primarily rely on solution blending or filler incorporation to enhance performance, this work demonstrates an architecture-driven strategy in which controlled layer-by-layer electrospinning enables simultaneous optimization of piezoelectric output, mechanical durability, and interfacial charge dynamics. The results establish LBL electrospun PVDF/TPU nanofibers as a scalable and tunable platform for next-generation self-powered and wearable energy harvesting devices.