The effect of ZnO-TiO2 fillers on the electroactive phase of PVDF and effective charge separation for fabricating high-performance piezoelectric nanogenerators

초록

The rapid development of self-powered systems in the modern era has necessitated the development of efficient and flexible composites for use in ambient-mechanical energy-harvesting devices. Various polymer-filler composites show significant potential for the development of efficient energy-harvesting devices. In this study, piezoelectric ZnO nanorods containing TiO2 nanoparticles were synthesized using a solvothermal method. ZnOTiO2 (ZT) was dispersed in poly (vinylidene fluoride) (PVDF) polymer matrix, and flexible ZT composite films were used to generate piezoelectric voltages through piezoelectric nanogenerators (PENGs). The optimized PENGs generated up to 23.2 V of voltage output with a tapping force of 20 N. The excellent piezoelectric behavior of the ZT/PVDF composite films is attributable to an enhancement in the electroactive-phase content of PVDF owing to PVDF stretching during supersonic spraying due to the presence of anisotropic ZnO nanorods, which affects the gamma-phase of PVDF. Simultaneously, the TiO2 nanoparticles generate isotropic stress and enhance nucleation. Moreover, mechanical mismatch between the nanorods and nanoparticles generates multidirectional stress fields, ultimately enhancing the piezopotential and power density (23.7 mu W cm(-2)). Finally, the compatibility of the flexible PENG electrodes was confirmed by testing their ability to convert biomechanical energy from different body movements, thereby validating the small-scale mechanical energy harvesting capacity of the fabricated composite PENGs.

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