基于压电-摩擦双重效应的高功率ZnO纳米发电机的制备及其相关机理研究

With the development of electronic devices into micro/nano scale, looking for a proper self-powered source that matches the size of electronic devices has presented innovative and emerging research topics. ZnO has been intensively studied as one of the most attractive piezoelectric materials for self-powered nanogenerators, which has potential applications in small electronics, implantable chips, environmental monitoring, biomedical and medical equipments, because of its unique piezoelectric semiconducting properties coupled with biocompatibility. However, the small output signals and low energy conversion efficiency limit the application of ZnO nanogenerators, because free charge carriers in ZnO partially screen the generated piezoelectric charges. In this project, by studying the influence of surface charges on distribution of ZnO piezoelectric potential, a novel hybrid nanogenerator based on piezoelectric and triboelectric effect is proposed by the incorporation of a negatively charged interlayer (i.e., friction layer), which may suppress the free carriers. In addition, the energy conversion efficiency of nanogenerator will be further enhanced and maximized by utilizing the multi-layer structure design, which provide a theoretical basis for further advance the practical process of nanogenerator.

随着电子器件不断向微纳尺度的发展，开发出与微纳电子器件在尺度上相匹配的自供电纳米电源成为当前的一个新兴的研究课题。氧化锌（ZnO）兼具压电、半导体、生物兼容特性，使得ZnO基纳米发电机在微型电子器件、植入芯片、环境监控、生物医学医疗仪器等方面有着巨大的应用潜力。但是目前报道的ZnO纳米发电机输出功率普遍很小，且能量转换效率非常低，主要是因为由ZnO形变而产生的压电电荷会和其内部的自由载流子发生中和。本项目通过研究表面电荷对ZnO压电电势的影响规律，创新性地提出一种压电-摩擦复合式纳米发电机，即通过引入容易带负电荷的插入层（即摩擦层），在ZnO表面形成反向静电电势，从而减少自由载流子浓度，提高纳米发电机的输出性能。此外，通过多层结构等设计方案，进一步提高纳米发电机的能量转换效率。本项目的研究成果为纳米发电机的发展与应用提供理论依据。

ZnO压电纳米发电机在微型电子器件、植入芯片、环境监控、生物医学医疗仪器等方面有着巨大的应用潜力。本项目的研究重心就是通过多种方法，制备多种复合式的纳米发电机，进而提高ZnO纳米发电机的输出功率和能量转换效率。本项目的研究成果包括：1）COMSOL软件理论分析了压电和摩擦输出电性能的影响因素，为制备高性能的纳米发电机奠定了理论基础。2）在原有制备ZnO压电纳米发电机的研究基础之上，引入插入层，研制出基于p-CuO/ZnO，p-Cu2O/ZnO，BaTiO3/ZnO等多种异质结结构的纳米发电机，大大提高了纳米发电机的输出性能。3）创新性地提出一种利用图形化ZnO纳米阵列的方法来提高纳米发电机输出性能，输出信号提高6倍。创新型提出一种可全方位搜集能源以及工作模式可切换的高性能可穿戴摩擦发电机。该发电机可产生电压信号和电流信号为100-200 V和0.5-1uA，可以直接点亮120盏商用LED，已经可以应用到生活当中。