Advances in wearable flexible piezoelectric energy harvesters: materials, structures, and fabrication

Flexible energy harvesters have become a research hotspot in both academia and industry because of their great advantages in powering wearable electronic devices. The flexible energy harvesters based on piezoelectric materials are recognized as a competitive method because of their sensitivity to mechanical deformation, excellent energy conversion performance, mature production technology, and simple structure. This paper presents a comprehensive review to illustrate the research progress and future development of wearable flexible piezoelectric harvesters. In this work, the widely used piezoelectric materials for flexible energy harvesters, including inorganic piezoelectric materials, organic piezoelectric materials, and piezoelectric composites, are first summarized. The research progress on the influence of ceramic content, morphology, distribution, surface chemical modification, and the addition of conductive materials on the properties of piezoelectric composites are systematically discussed. Additionally, this paper also presents novel structures and fabrication methods of flexible piezoelectric energy harvesters. Finally, future trends in research, development, and innovation of flexible piezoelectric energy harvesters are outlined and prospected.