Superior transverse piezoelectricity in organic-inorganic hybrid perovskite nanorods for mechanical energy harvesting

Developing highly piezoelectric nanoparticles (NPs) with inherent mechanical-electrical coupling effect is critically important for energy harvesters, self-powered sensors and actuators. Over the past decades, the NPs with a high longitudinal piezoelectric coefficient (d 33 ) were developed for piezoelectric nanogenerators (PENGs) that operate under periodic vertical compression mode. As an alternative, high-performance PENGs can be developed by taking advantage of materials with a superior transverse piezoelectric coefficient (d 31 ). In this work, we successfully synthesized an organic-inorganic hybrid perovskite (OIHP) nanorods (NRs) of (4-aminotetrahydropyran) 2 PbBr 2 Cl 2 [(ATHP) 2 PbBr 2 Cl 2 ] that exhibits a large d 31 of 64.2 pC/N, which is 3 times higher than the well-known poly (vinylidene fluoride) (PVDF) polymer (21 pC/N). A saturated polarization of 5.4 μC/cm 2 and a piezoelectric voltage coefficient (g 33 ) of 900 mV•m/N are also reported. The (ATHP) 2 PbBr 2 Cl 2 NRs can be dispersed homogeneously in a polymer matrix to make piezoelectric composite films. Due to their excellent flexibility, uniform dispersion and large surface area the concurrent vertical strain and lateral bending yield a high piezoelectric performance. We fabricate a unique piezoelectric composite film for PENGs, which can produce an output voltage (V oc ) of 90 V and a short-circuit current (I sc ) of 6.5 μA under an applied force of only 4.2 N, outperforming a number of the state-of-the-art PENGs ( Table S2 ). The harvested electrical energy is stored in a capacitor by a two-stage energy transfer mechanism for self-powered electronics. This is the first work, that not only reveals the large transverse piezoelectricity in the (ATHP) 2 PbBr 2 Cl 2 NRs, but also coins a route to employ it in practical energy harvesting devices. • Synthesis of (ATHP) 2 PbBr 2 Cl 2 hybrid perovskite nanorods (NRs) for mechanical energy harvesting applications. • The nanorods exhibit a transverse piezoelectric coefficient (d 31 ) of 64.2 pC/N, 3-times higher than the PVDF film. • The (ATHP) 2 PbBr 2 Cl 2 @PDMS film generates an output voltage of 90 V and a current of ~ 6.5 μA with an applied force of 4.2 N. • The PENGs can charge a 1 μF capacitor to 5.5 V in 20 s and promising to be integrated with the electronic circuits.