新型热释电纳米发电机及自驱动传感研究

Wasted heat with a spatially uniform and time-dependent temperature is a rich source of energy in an environment, which can not be usually harvested based on the Seebeck effect. However, the pyroelectric effect has to be the choice, which is based on the spontaneous polarization in certain anisotropic solids due to a time-dependent temperature variation. How to use pyroelectric effect for efficiently and expediently harvesting thermoelectric energy is the key to achieving the electricity generation from the wasted heat without a spatial temperature gradient. On the other hand, an external power source is indispensable to sensors. The traditional method for driving sensors relying a power grid or battery is not able to meet the working requirements and is not suitable for future working environment of the future sensor network. In this project, we invent a new type of nanogenerators based on the pyroelectric effect——single-electrode pyroelectric nanogenerators, by using the integration of the ferroelectric oxide thin films with metal electrodes. The fabricated nanogenerator will be utilized for harvesting wasted thermoelectric energy and as a self-powered sensor operating without external power sources or batteries. Meanwhile, by combination of the experimental measurement with the established physical model, the electric-generation mechanism and self-powered sensing mechanism of the single-electrode pyroelectric nanogenerator will be proposed systematically, revealing the deep physical nature.

环境中存在着大量的温度空间分布均匀却随时间变化的废弃热能。利用塞贝克效应通常无法收集这种能量，而热释电效应是必须的选择，它是关于自发极化在某些各向异性的固体中随温度涨落的结果。如何利用热释电效应来高效地、方便地收集环境中的热能是实现温度没有空间梯度的废热发电的关键。另外，目前所有的传感器都需要外界对其供电或者安装蓄电池才能工作。传统的依靠电网或者蓄电池来供电的方法将不能满足或者不能适应传感器网络未来的工作要求和环境。本项目将基于热释电效应，采用将铁电氧化物薄膜集成生长于金属电极的方法，构建出一种新型的纳米发电机，即单电极热释电纳米发电机，并利用该纳米发电机收集环境中废弃的热能以及用作不需要外界电源或者蓄电池而能够工作的自驱动传感器。同时，结合实验测试以及建立的物理模型，系统地分析单电极热释电纳米发电机的发电原理和自驱动传感原理，揭示其中蕴藏的物理本质。

对环境热能和机械能的收集，是实现能量综合利用的有效方法，也是解决大规模无线传感器供电问题的关键途径。本项目基于PVDF薄膜构建了热释电纳米发电机，研究了热释电发电技术的原理，并在此基础上，将热释电发电技术与其他物理效应耦合，发明了多种形式的复合纳米发电机，深入研究了复合纳米发电机的工作机制。最后，基于纳米发电机设计了多种类型的有源传感器件并研究了自驱动传感机理。主要的研究结论包括：（1）通过研究基于PVDF薄膜的热释电纳米发电机的结构设计、工作机制、性能输出等，实现了基于热释电效应的环境热能高效收集，揭示了其工作机理。（2）将热释电发电技术与其他技术耦合，构建了复合纳米发电机，研究了复合纳米发电机在多物理场条件下的功能转换机制。（3）通过将不同形式的纳米发电机应用于不同条件下的有源传感，实现了基于纳米发电机的自驱动传感，揭示了自驱动传感机制。本项目以实验为主要手段并结合理论仿真，研究了纳米发电机在能量收集与自驱动传感的功能转换机制，极大地拓展了基于纳米发电机的应用范围，对纳米器件的发展具有较好的指导意义。