All-inorganic halide perovskite tuned robust mechanical-energy harvester: Self driven posture monitor and power source for portable electronics

Scavenging electric power at ambient from biomechanical movements and mechanical vibrations using piezoelectric nanogenerators (PNGs) has become an accessible energy alternative for the development of self-powered electronic systems and miniaturized power sources for small-scale wearable/portable devices. Here, caesium lead chloride (CsPbCl₃)-embedded β-phase comprising polyvinylidene fluoride (PVDF) hybrid films turns to a suitable functional material for piezoelectric-based mechanical energy harvesters. Incorporation of CsPbCl₃ in the PVDF matrix enables high crystallinity and nucleation of electroactive β-phase ∼86% in the PVDF with piezoelectric coefficient d₃₃ of 49 pm/V, much higher as compared to pristine PVDF. Dielectric study as a function of perovskite concentration at room temperature reveals dielectric constant of ∼ 66 and low dissipation factor of 0.21 at 1 kHz for optimized hybrid. Saturated ferroelectric P-E hysteresis loop analysis of the synthesized samples indicates variation in remanent polarization with perovskite content. The fabricated PNG delivered instantaneous output voltage of 168 V and peak-to-peak output current of 2 μA. High sensitivity of the flexible PNGs enables us to measure even a slight deformation due to bending by 2˚. Considering its good flexibility and high electrical output performance, optimized PNG was utilized for the fabrication of wearable self-powered posture sensor to monitor regular movement of our spine. Walking based wearable PNGs are also devised for powering up normal android mobile phone batteries. Fatigue test of PNG for continuous 10,000 cycle operation, even after 5 months from the fabrication time, highlights its robustness. Considering such simple and unique amalgamation of polymer and perovskite, these highly flexible PNGs can be easily integrated in portable electronic devices and with the advantage of biomechanical movements as the source of power.