Additively manufactured flexible piezoelectric lead zirconate titanate-nanocellulose films with outstanding mechanical strength, dielectric and piezoelectric properties

Nanocellulose (NC)-based piezoelectric films prepared via solution casting show low mechanical, dielectric, and piezoelectric performance due to the randomly oriented cellulose nanofibers and dispersion of piezoelectric domains. Moreover, a high electric field for piezoelectric domain alignment may also increase the brittleness of the piezoelectric films. For the first time, an additive manufacturing (AM) technology is demonstrated to fabricate high mechanical strength and flexible NC-based piezoelectric films efficiently. Different concentrations (10, 20, and 30 wt%) of lead zirconate titanate (PZT) particles are mixed in the NC suspension and additively manufactured, followed by drying at cleanroom conditions. Next, the magnetically induced electric field is introduced into the PZT-NC films coated with silver electrodes. The obtained flexible piezoelectric PZT-NC films show outstanding mechanical strength of 203.5 ± 4.8 MPa, good flexibility, high dielectric constant (87.7 at 1 kHz), low dielectric loss (0.09 at 1 kHz), and high piezoelectric constant (d₃₃ = 53 pC/N). Furthermore, the 30PZT-NC piezoelectric nanogenerator showed a peak-to-peak voltage of 2.24 V and an output power density of 1.56 μW/cm³. The measured mechanical, dielectric, and piezoelectric properties are superior to the previously reported NC-based piezoelectric and commercially available PVDF films. Based on the outstanding multifunctional properties of NC-based piezoelectric films, AM technology can replace traditional solution casting methods and open a wide range of applications in flexible piezoelectric materials.