Nanogenerators Based On Triboelectrification Of A Dielectric Composite Made Of ZnSnO₃ Nanocubes

In recent decades, the resource scarcity, pollution and other environmental problems have caused great concern of mankind, which result from the excessive consumption of resources and rapid popularization of the mobile electronic device. So more and more voices call on the development and utilization of new green renewable energy, and more and more researches focus on the energy collection, conversion, and utilization. In 2006, the advent of nanogenerators is one of the most important technological advancements that can transfer mechanical energy into electrical energy in the surrounding environment anytime and anywhere, thus realizing the energy supplying to small mobile electronic devices in the form of a transducer. This great breakthrough has extensive and far-reaching application value. In this paper, our main research content focused on the flexible triboelectric nanogenerator（TENG） based on the PDMS composite film. By dispersing the semiconductor piezoelectric nanomaterial ZnSnO₃ into PDMS, the organic electret material PDMS can be modified, then we studied the modified TENG based on the ZnSnO₃@PDMS composite film. And the main contents and conclusions of this paper are as follows:（1） The synthesis and characterization of ZnSnO₃ nanocrystal1) ZnSnO₃ nanocrystal has been synthesized from Zn（Ac）₂·6H₂O, SnCl4·5H₂O, NaOH and HMTA by a hydrothermal synthesis method. And the phase present, morphology and chemical compositions have also been characterized later.2) Integrating the characterization results obtained from XRD, SEM and EDS, they show that the hydrothermally synthesized ZnSnO₃ products are pure with perfect crystallinity, besides exhibiting a well-defined cubic nanostructure with a smooth surface and ruled edge.（2） The TENG based on ZnSnO₃@PDMS composite film1) The preparation and characterization of ZnSnO₃@PDMS composite film: The composite films were prepared by dispersing ZnSnO₃ nanocubes at various concentrations into PDMS through a model heat curing method. And the surface and cross-sectional FE-SEM images of composite films were also analyzed, which showed the ZnSnO₃ nanocubes could be well-distributed in PDMS, existing no suspension or sink phenomenon.2) The fabrication and measurements of TENG: This TENG device was fabricated by using a simple two-electrode system, where Al foils acted as electrodes separated by the ZnSnO₃@PDMS composite film. The electrical contact was taken from the two opposite electrodes with Cu wires. To optimize the TENG output performance, TENGs were fabricated with various doped ZnSnO₃ concentrations, different composite film thickness. From these results, it shows a maximum output up to 400 V, 28 μA and 3 mW（7.5 W/m2） can be generated from the TENG based on a composite film with 6 wt% of ZnSnO₃ and a thickness of 0.5 mm. The harvested energy can drive 53 blue LEDs in parallel. Besides the stability testing of TENG was also done during the periodic compressing-releasing process, which showed excellent stability and durability of TENG.（3） Working mechanism of the TENGThe working mechanism of TENG can be explained from the designed macro-structures and controlled micro dielectric materials of TENG. First, based on the design of the macro-structures, we explained the process of TENG exporting cycle alternating current/voltage. Secondly, based on the research about the combination of organic polymer and inorganic dielectric materials, we studied quantitatively the dependency of the TENG’s output performance on the doped concentration of ZnSnO₃ in the composite film. This fundamental mechanism has also been validated by the measurement of the composite film’s surface charge density by EFM, which further confirmed its rationality. This study makes a certain significance on how to choose a better or get a better electret material by modification to improve the surface charge amount of the dielectric materials, and ultimately enhance the output performance of the nanogenerators.