Piezoelectric nanogenerator based on lead-free perovskite embedded pvdf composite for biomechanical energy harvesting application

Abstract

This study of the thesis work has been conducted with an objective to develop concepts and knowledge about perovskite-based material for energy harvesting application. Here we have studied some previous work on this topic. We have gone through the history, basic working principle, properties and what could be the possible future of this technology. In the course of literature surveying there are some research paper, scientific journals have been studied to develop ideas on different types of perovskite materials available having good electrical, chemical and optoelectronics properties. Exploited with the merits of easy congregation, conformal structure, flexible and self-powered piezoelectric nanogenerators (PENGs) have become a sustainable and attainable energy alternative. Following this trend, a novel piezoelectric sensor is fabricated by a composite of room temperature processed all-inorganic cesium antimony bismuth chloride (Cs3SbBiCl9) layered perovskite and polyvinylidene fluoride (PVDF) nanofiber. Studies on this novel material have already indicated its high electrical conductivity and tunable bandgap claiming the same as one of the promising materials for “piezo electronics”. Hence, we have selected this novel perovskite for this thesis work and focused on colloidal synthesis technique, investigation of its different physical and electrical properties, device fabrication and several interesting applications. We started from the cost-effective chemical technique “colloidal” route to synthesize Cs3SbBiCl9. We had selected this synthesis route as it requires simple experimental set-up, minimum production cost compared to other techniques. From the Industrial application point of view large scale production for proper use of any advanced material is achievable. So, colloidal synthesis technique also fulfils these criteria. Moreover, several synthesis parameters like doping concentration, temperature and synthesis duration can be controlled efficiently. So, we opted for colloidal synthesis in our work. Characterization of the synthesized samples was done with X-ray diffractometer (XRD) for phase information. Field emission scanning electron microscopic (FESEM) studies was carried out to obtain the morphology of Cs3SbBiCl9 samples. FTIR spectroscopy studies were carried out to investigate the electroactive phase content of the material. Detailed studies were performed using LCR meter to observe the nature of dielectric and ferro electric properties like piezoelectricity which is an important aspect of our material. Piezoelectric energy generation from the devices has been investigated under several simple human body movements like hammering by hand, finger tapping, knee bending, bending by arm, etc. Optimized Cs3SbBiCl9-PVDF composite (with 5 wt% of Cs3SbBiCl9 loading) based PENG delivered an output power 4.22 mW with high open-circuit voltage of 273 V and short-circuit current of 15.45 μA. Such promising output value for the composite sample suggests much improved energy conversion efficiency as compared to the pristine PVDF separately. This device is also capable of lighting up several commercial LEDs. Increase in output values is attributed to the improved polarization in PVDF by Cs3SbBiCl9 incorporation. Furthermore, photosensitivity has been indicated in other journals, which designated its potential as photodetector. Considering the photo and electroactive properties, a new class of self-powered photoactive piezoelectric energy harvester has also been fabricated. Such results culminate the practical design of all inorganic perovskite-based nanostructure in optimizing device performance and thereby providing a useful way to develop new hybrid materials for piezo-phototronics.