An article published recently in the journal Materials Today: Proceedings sheds light on the fabrication of pliable piezoelectric nanogenerators (PENGs) made from a combination of polyvinyl fluoride (PVDF) and tin sulfide (SnS2).
Study: High performance piezoelectric energy harvesting based on PVDF-SnS2 nanocomposite. Image Credit: sakkmesterke/Shutterstock.com
The nanoscale composite was drop-cast to generate pliable thin sheets after 2D-SnS2 was manufactured using a straightforward hydrothermal technique and combined with PVDF.
Piezoelectricity – A Much Needed Source of Clean Energy
Due to the prevalent energy crisis and ecological concerns, there has been an increase in the requirement for greener and more sustainable energy sources in recent years. Therefore, there is a pressing need to explore the utilization of alternate solutions like photovoltaic or mechanical power, which are more environmentally friendly than fossil fuels.
Piezoelectric effect is the fundamental idea behind the conversion of mechanical energy to electrical energy. Utilizing piezoelectric nanogenerators (PENGs), mechanical energy in oscillations, biological motions, or environmental perturbations may be harnessed to generate electricity.
2D Materials Could be the Key in Energy Harvesting Applications
The large interface width and short diffusion route length of 2D nanostructured materials make them great candidates for sensors, energy harvesters, and optoelectronics applications. The employment of two-dimensional metal dichalcogenides (MDs) nanoelectronics is currently the focus of extensive studies due to their favorable electrical, optical, and chemical properties.
MD crystals are made up of two-dimensional sheets that are layered on top of one another using weak van der Waals contact forces. At the same time, the much stronger covalent bonding handles intralayer contacts. This allows for the stable formation of crystals with atomic-scale depth. This feature of MDs is being investigated experimentally to study their possible application in harvesting energy employing PENGs.
Enhancing Polyvinyl Fluoride for Improved Piezoelectricity
Polyvinyl fluoride (PVDF) is a non-toxic, environmentally friendly, robust, and elastic fluoropolymer in several morphologies such as a, b, c, and d.
Owing to its all-trans arrangements, polyvinyl fluoride in its b-phase exhibits a special piezoelectric effect amongst all the structural phases.
There are several methods for improving the b-phase of polyvinyl fluoride, including chemical, mechanical, and thermal enhancements. Aside from these known approaches, the introduction of supplements such as ZnO has been acknowledged as an effective way for improving the b-phase of PVDF. There are, however, just a handful of studies that propose MDs as efficient supplements for b-phase augmentation in PVDF.
Advantages of Using Tin Sulfide
The tin sulfide (SnS2) crystal is n-type, made of thick layering of tin (Sn) sheets in-between two sulfur (S) sheets, and possesses a bandgap that varies from 2.12 to 2.14 eV depending on the fabrication technique utilized. Owing to its remarkable charge carrier movement and optical absorbance coefficient, it is perfect for creating thin sheets for a variety of optoelectronic applications. Furthermore, the tin and sulfur, which make up SnS2, are non-toxic, abundant, and inexpensive.
Main Goal of the Study
Despite having significant piezoelectric coefficients, single-layer MDs are not regarded as suitable materials for constructing piezoelectric devices due to their poor durability and wearability.
To address this, the researchers created innovative, elastic PENGs based on the nanoscale composite of PVDF and SnS2 and evaluated the effect of the weight percentage of SnS2 on the performance of PVDF-SnS2 based PENGs. Owing to the elasticity provided by PVDF, the fabricated PENG thin sheets showed excellent wearability.
This article reported the successful synthesis and study of an elastic piezoelectric energy harvester predicated on thin sheets of PVDF-SnS2 nanoscale composite. After employing Raman scattering and XRD analyses to validate and characterize the fabricated SnS2, it was incorporated into the PVDF in incremental weight percentages.
The piezoelectric response of PVDF-SnS2-based PENGs was discovered to be significantly sensitive to the amount of tin sulfide introduced to PVDF. XRD research further demonstrated that incorporating tin sulfide into the PVDF lattice enhanced the b-phase and thus the total piezoelectric effect.
To investigate the effectiveness of the PENG unit in producing electrical energy, the output currents and voltages of all units with varying weight percentages were measured. The highest piezoelectric voltage yield of the PENG manufactured at 7% SnS2 was approximately 4.5 times that of the raw PVDF-based PENG.
A similar pattern was seen for the produced piezoelectric current, with the 7 percent SnS2 PENG generating 24.1 nA current, about 15 times that of the raw polyvinyl fluoride thin film. Therefore, this study revealed that by including tin sulfide into the PVDF framework, the piezoelectric capabilities of PVDF-based energy harvesting systems might be greatly improved.
Gautam, G., Kumar, M., and Singh, B. (2022). High performance piezoelectric energy harvesting based on PVDF-SnS2 nanocomposite. Materials Today: Proceedings. Available at: https://doi.org/10.1016/j.matpr.2022.04.222