Superiority of 1D micro-rod to micro-particle fillers for ferroelectric and energy conversion performance of KNN/P(VDF-TrFE) composites

To enhance the piezoelectric properties of poly (vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))-based composites and prepare a piezoelectric sensor with high sensitivity, two types of potassium sodium niobate (KNN) fillers, micro-particles (MPs) and micro-rods (MRs), were individually doped into a P(VDF-TrFE) matrix to form composites using a traditional solution-casting process. Identically, the two groups of P(VDF-TrFE)-based piezoelectric composites doped with KNN MPs and KNN MRs exhibited an enhanced β-phase and typical ferroelectricity with high residual polarization (P_r), which resulted in good piezoelectric constant (d₃₃) and sensing electrical response. In contrast, the KNN MRs/P(VDF-TrFE) composite showed better piezoelectric output performance compared to the KNN MPs/P(VDF-TrFE) composite in all test scenarios, which is attributed to its depressed dielectric permittivity owing to the ameliorative conductivity dielectric loss. An output voltage (U) of 16 V, 4 V, and 6 V were recorded using 10 g zirconium ball impacting, finger tapping, and finger bending, respectively, in the KNN MRs/P(VDF-TrFE) sensors. This research demonstrates the impact of the filler shape on the electrical performance of P(VDF-TrFE)-based piezoelectric composites, which provides a reliable reference to enhance the energy harvesting and conversion performance of self-powered electronic devices.