Enhanced Polarization in Ferroelectric Composites via DIW-Controlled Perovskite Nanosheet Orientation

PVDF has expanded the application of ferroelectric materials in flexible and wearable electronics due to its flexibility, corrosion resistance, ease of processing, and low cost. However, the polarization of ferroelectric polymers is low, with a bottleneck value of 10 µC cm−2. In this study, flexible ferroelectric composite films comprising Ca2Nb3O10 (CNO) nanosheets and PVDF were fabricated via direct ink writing (DIW). By modulating the nozzle-to-substrate height in conjunction with flow-induced shear within the syringe and the application of additional shear force at the nozzle, effective alignment of low-content (2 wt.%) CNO nanosheets dispersed in a highly fluid ink was achieved. The enhanced orientation degree of the CNO nanosheets increased the breakdown strength of the PVDF–CNO composite films to 524 MV/m. Furthermore, the remanent polarization (Pr) was significantly increased by 207% compared to pure PVDF films, reaching a value of 11.6 µC cm−2. This study provides a simple and efficient DIW-based strategy for improving filler orientation in composites and demonstrates the substantial enhancement in dielectric and ferroelectric properties achievable through such filler alignment.