Flexible sheets of lead free KNN-PVDF composite: A sustainable pyroelectric energy harvester

In the present work, flexible Potassium Sodium Niobate - Polyvinyledene Fluoride (KNN-PVDF) composite sheets have been developed and utilized for the realization of a highly efficient pyroelectric energy harvester. KNNPVDF composite sheets with varying the weight % of KNN (10-50 %) have been synthesized using solution casting method. The influence of KNN (Potassium Sodium Niobate) on the structural, morphological, and dielectric properties of PVDF has been investigated. The highest value of pyroelectric coefficient of 14.7 x 10 -4 Cm- 2K- 1 has been obtained for the flexible sheets of 30 % KNN-PVDF composite with change in temperature. It has been also observed from the ferroelectric studies that a high value of saturation polarization of 1.44 mu C/cm2 is obtained at the applied bias of 5 V and 50 Hz frequency due to the presence of 30 % KNN in the KNN-PVDF composite sheets. The obtained results show the potential application of non-toxic, lead free KNN-PVDF composite sheets for thermal energy harvesting applications utilizing pyroelectric effect.