Multi-layered laminate architectures enhance the electromechanical response of PVDF-TrFE films

The digitisation of society and the rise of autonomous sensing networks have led to the need for independent and autonomous low-grade power supplies. Electromechanical harvesters, which convert motion or vibrations into electricity, show great promise for powering microelectronic devices. In particular, poly(vinylidene difluoride (PVDF) is an exemplar polymer material for electromechanical conversion and is highly attractive as a power source due to its exceptional chemical stability. In this study, we present an approach to enhance the electromechanical conversion of a PVDF co-polmyer by electrospinning multi-layered nanofiber laminate architectures, consisting of alternating smaller and larger diameter fibers. This alternative layer structure results in the introduction of oriented triboelectric dipoles within the volume of the laminate architecture, able to couple with the piezoelectric dipole of PVDF. The laminate shows an 11× improvement in electromechanical conversion when compared to an equivalent single diameter fiber network under identical conditions. The application of the laminate architecture to airflow and sound energy harvesting is also demonstrated, with a doubling of the peak-to-peak short-circuit current compared to a state-of-the-art commercial poled PVDF film. This approach provides a pathway to improve the electromechanical performance of PVDF for a wide array of electromechanical conversion applications.