A comprehensive investigation on metal–organic framework based poly(vinylidene fluoride) composites as piezoelectric nanogenerators.

Highlights Copper based metal–organic frameworks (Cu‐MOF) incorporated poly(vinylidene fluoride) (PVDF) composites were processed using drop casting, with different concentrations of Cu‐MOF (0.15–2 wt.%). Ultrasonication and centrifugation of Cu‐MOF particles were adopted as pre‐processing steps to ensure effective de‐agglomeration of the Cu‐MOF particles. The formation of polar β‐crystalline phase in PVDF/Cu‐MOF composite was confirmed by the morphological observation of fibrillar microstructure and the manifestation of specific absorption bands via spectroscopic analysis. Further, FTIR and NMR spectroscopic analyses unequivocally established the interfacial interactions between Cu‐MOF particles and PVDF dipoles. A maximum of ~92% polar fraction and ~25 pm/V d33 was obtained in PVDF composite of 1 wt.% of Cu‐MOF. Dielectric and ferroelectric investigations were carried out to relate the improvement of the interfacial polarization. Moreover, energy harvesting devices were fabricated from PVDF/MOF composites and a maximum rectified piezoelectric voltage of ~40 V was recorded during finger tapping experiment in PVDF/MOF composite of 1 wt.% Cu‐MOF. Further, a load current and maximum volumetric power density of 7.5 μA and ~1.2 mW/cm3, respectively, were achieved. The usage of the fabricated device as an energy harvester was further established by charging and discharging different capacitors and illuminating LEDs. Cu‐MOF (0.15–2 wt.%) incorporated PVDF composites were processed by solution casting. A maximum of ~92% polar fraction was obtained in PVDF/1MOF composite. A maximum rectified output voltage of ~40 V was recorded in PVDF/1MOF composite. A higher power density (1.2 mW/cm3) and load current (7.5 μA) were achieved for PVDF/1MOF. The usage of the fabricated device as an energy harvester was further established. [ABSTRACT FROM AUTHOR]