Modulation of piezoelectricity and mechanical strength in piezoelectric composites based on N0.5B0.51T-BNT nanocubes towards human-machine interfaces

Perceiving mechanical stimuli via piezoelectric nanogenerator (PENG) is attractive for constructing the self-powered sensing system in the field of human-machine interaction. However, the inferior piezoelectricity of the lead-free piezoelectric materials leads to the relatively low sensitivity of PENG. Herein, a 90 nm lead-free off-stoichiometric 0.95Na0.5Bi0.51TiO3-0.05Ba(Ti0.5Ni0.5)O3-δ (N0.5B0.51T-BNT) single crystal was facilely synthesized by hydrothermal method. Compared to stoichiometric 0.95Na0.5Bi0.5TiO3-0.05Ba(Ti0.5Ni0.5)O3–δ, the piezoelectric coefficient presents four folds enhancement, which is associated with the enhanced local structural heterogeneity. By using glass fiber fabric (GFF) as the reinforcing matrix, a mechanically robust PENG based on N0.5B0.51T-BNT is obtained, which delivers a short-circuit current of ∼1.8 μA, and an open-circuit voltage of ∼33.8 V. Meanwhile, the composite film exhibits excellent mechanical strength which can lift the object over 10,000 folds heavier than its own weight successfully. By virtue of the high sensitivity (1.94 V/N, 95.99 nA/N), we assembled the PENG into a 3 * 3 wireless sensing array for the function of the long-distance smart switch and gesture interaction system, which commendably broadens the application scope of the piezoelectric arrays as intelligent sensors.