Output characteristics of thin-film flexible piezoelectric generators: A numerical and experimental investigation
Output characteristics of thin-film flexible piezoelectric generators: A numerical and experimental investigation
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DOI：
10.1016/j.apenergy.2019.113856
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发表时间：
2019-12-01
期刊：
影响因子：
11.2
通讯作者：
Ryou, Jae-Hyun
中科院分区：
文献类型：
--
作者：
Chen, Jie;Nabulsi, Noor;Ryou, Jae-Hyun
柔性压电式发电机通过将周围的机械能转化为电能，有望成为未来自给式电子产品的能量收集器。尽管已有多种类型的柔性压电源被证明，但由于其输出特性的复杂性，其输出特性依赖于包括压电器件参数和外部机械能条件在内的许多因素。本文采用基于屈曲弯曲模型的数值模拟方法，系统地研究了柔性压电发电机的输出特性。通过对III族氮化物薄膜柔性压电发电机的实验验证了数值计算结果的可靠性。理想的开路电压和短路电流密度分别与压电材料的应变和应变率成正比。对于特定的器件，在一定的机械条件下，压电体的输出随负载电阻的变化而变化，并在一定的负载电阻下表现出最大功率密度，即最佳负载电阻。最佳负载电阻随压电材料厚度、器件面积的倒数和弯曲时间呈线性增加，而不随柔性衬底厚度和弯曲程度的变化而变化。最佳功率密度随压电材料厚度、柔性衬底厚度的平方、弯曲时间的反比和弯曲程度的增加而线性增加，而不随器件面积的变化而变化。对柔性压电式发电机输出特性的详细了解有助于优化装置结构，以更好地收集压电能量。
Flexible piezoelectric generators are promising energy harvesters for future self-powered electronics by converting surrounding mechanical energy into electricity. Although many types of flexible piezoelectric generators have been demonstrated, their output behaviors are still not systematically reported due to the complexity since the behaviors depend on many ingredients including piezoelectric device parameters and external mechanical energy conditions. In this research, numerical simulations based on a buckle-bending model were carried out to systematically investigate the output characteristics of flexible piezoelectric generators. The reliability of the numerical results were verified through experimentation using group III-nitride thin-film flexible piezoelectric generators. The ideal open-circuit voltage and short-circuit current density are proportional to the strain and strain rate of the piezoelectric material, respectively. For a specific device at a certain mechanical condition, the piezoelectric output varies with load resistance and shows a maximum power density at a certain load resistance, i.e., optimum load resistance. The optimum load resistance increases linearly with piezoelectric material thickness, inverse of device area, and bending time, while does not change with flexible substrate thickness, and bending extent. The optimum power density increases linearly with piezoelectric material thickness, square of flexible substrate thickness, inverse of bending time, and bending extent, while does not change with device area. The detailed understanding of the output characteristics of flexible piezoelectric generators can help the optimization of device configuration for better piezoelectric energy harvesting.