BaTi_0.95Hf_0.05O₃ Incorporated PVDF Flexible Composite Films for Energy Storage, Harvesting, Sensing, and UV Shielding

Abstract Multifunctional piezoelectric devices, capable of sensing force/pressure, harnessing power from changes in human body postures, shielding ultaviolet‐visble (UV–vis light), and storing electrostatic energies, can fulfill the daily requirements of modern lives. Consequently, a novel polyvinylidene difluoride (PVDF)‐barium hafnium titanate (BaTi_0.95Hf_0.05O₃) composite is synthesized. BHT5 comprises a mixture of 42.11% tetragonal and 57.89% orthorhombic phases at room temperature, with a d₃₃ = 193 pC/N. XRD confirms the presence of peaks corresponding to PVDF and BHT5 in the composite films. The fraction of the beta phase increases from 78% to 94% with increases in BHT5 weight percentage (wt.%) from 10% to 40%. The dielectric constant, piezo voltage, current, and power density increase with BHT5 wt.% in composite films. However, a decrease in remanent polarization, saturation polarization, and coercive field is observed with a rise in filler wt.%. PVDF‐BHT5‐40 generates output voltages of 9.3, 12.8, and 5.0 V upon hand tapping, fist beating, and elbow bending, respectively. A maximum of 36.6 V is achieved across a resistance of 0.1 MΩ. PVDF‐BHT5‐40 film generates a 28 V voltage, 31 nA current, and 26.79 µW cm⁻³ power density upon applying 50 N @5 Hz. Absorbance increases with filler concentration, indicating the efficiency of the composite film to shield UV light.