High-Performance Piezoelectric Nanogenerator Based on Odd–Odd Nylon Nanofibers for Wearable Electronics via Precise Control of Ferroelectric Phase and Orientation

Piezoelectric nanogenerators (PENGs) have been attracting considerable attention as an efficient solution for harvesting environmental mechanical energy. Among the piezoelectric materials for the fabrication of PENGs, piezoelectric polymers have shown unique advantages, particularly for self-powered systems in wearable devices. However, the variety of piezoelectric polymers studied for the PENG development has been relatively limited, leaving room for advancements in their performance. In this study, we introduced odd-odd piezoelectric nylon (nylon 11,11) for the first time for PENG fabrication. Electrospinning conditions were studied to yield nylon 11,11 nanofibers with uniform morphology and optimized piezoelectric crystalline states. The influence of concentration of the electrospinning solution on the fiber morphology and piezoelectric-active γ crystal structure is elucidated, and the applied electric field is found to be critical in controlling the orientation of the ferroelectric crystal domain. Further, the correlation between the outputs of the as-prepared PENG and the characteristics of the nanofiber mats was established. Finally, the piezoelectric output of PENGs fabricated by NF-20 reached the maximum values, an open-circuit voltage of up to 22.0 V and a short-circuit current of approximately 300 nA, when subjected to a compressive force of 20 N at a frequency of 5 Hz on an area of 6.25 cm2. Also, it enabled the conversion of mechanical energy into electricity with an instantaneous output power density of 9.13 mW m–2 (60.9 mW m–3, 0.18 GΩ). Importantly, the as-prepared PENGs consistently exhibit unwavering and reliable piezoelectric performance in a variety of practical applications, including continuous compression, successive daily wear, energy harvesting from routine physical activities, and the transition of sign language into electric signals. Therefore, nylon 11,11 nanofiber PENGs hold substantial potential and advantages for the design of self-powered devices and electromechanical responsive equipment. Piezoelectric nanogenerators based on nylon 11 enable efficient harvesting of environmental energy, serving as a green energy source.