Harnessing self-powered and photoresponsive biomechanical activity sensors by exploring the piezo-phototronic effect in lead-free layered halide perovskite/PVDF composites

Abstract

Developing flexible, wearable, efficient, and self-powered electronic devices based on piezoelectric nanogenerators aspires to be a sustainable solution to renewable energy harvesting and storage. We report on a lead-free halide perovskite Cs3Sb2I9 and polyvinylidene fluoride (PVDF) based composite device capable of scavenging energy from routine biomechanical activities. Regulated incorporation and optimization of Cs3Sb2I9 into the PVDF matrix increased the electroactive phase of the device to ∼82% with a piezoelectric coefficient of 7.48 pm V−1. The champion device produced an open circuit output voltage of 85 V and a current of 2.6 μA. Furthermore, the device generated approximately ∼1.26 μW cm−2 of power density when connected to a 0.8 MΩ resistor, sufficient to operate portable electronic gadgets. We tested the device for its energy generation capabilities under simple human biomechanical movements such as hand hammering, finger tapping, elbow bending, knee bending, and toe pressing. To demonstrate the versatility of the nanogenerator device, we also tested its energy generation and storage capabilities by charging capacitors up to ∼2.2 V. The device exhibited impressive durability and repeatability over 10 000 cycles, underscoring its potential as a promising solution for addressing the energy demand of portable and Internet of Things (IoT) devices through piezoelectric nanogenerators. Work function calculations using density functional theory demonstrated that the composite exhibited a reduced work function compared to individual components, indicating favorable electron emission characteristics. We also realized the piezo-phototronic effect in the composite using a self-powered photodetector, which exhibited an increment of 63% in the photocurrent, offering potential for piezotronic and optoelectronic devices.