Synthesis of KNN nanoblocks through surfactant-assisted hot injection method and fabrication of flexible piezoelectric nanogenerator based on KNN-PVDF nanocomposite

With the tremendous growth of flexible piezoelectric nanogenerators, alkali niobates have gained considerable attention and are perceived to be the eco-friendly substitute for the unsustainable lead based piezoelectric systems. However, successful realization of potassium sodium niobate (KNN) based devices with appreciable piezoelectricity requires tailored molecular level organization. Herein, we have developed a lead-free flexible piezoelectric nanogenerator based on KNN-PVDF nanocomposite, in which the KNN nanoblocks were synthesized using a novel non-aqueous surfactant-assisted hot injection method. Also, the synthesis of KNN employed non-toxic surface stabilizer, oleic acid and reaction catalyst, oleyl amine respectively, making the preparation environmental benign. The KNN nanoblocks homogeneously dispersed in the PVDF matrix up to 10 wt% filler loading, enhanced the piezoelectric and dielectric properties of the composite. Further, the fabricated flexible piezoelectric nanogenerator without any external poling process exhibits an output open circuit voltage of ∼ 2.1 V and a short circuit current of ~ 42 nA on a gentle finger tapping force (~3 N). The results demonstrate the potential of chemically engineered KNN nanoblocks dispersed in PVDF for large-scale sustainable piezoelectric nanogenerator applications. • Piezoelectric KNN nanoblocks were synthesized by a novel, environmental benign, surfactant-assisted hot injection method • An eco-friendly, flexible piezoelectric nanogenerator (PENG) based on KNN-PVDF nanocomposite has been fabricated • With a gentle finger tapping, the PENG exhibits an open-circuit voltage of ~ 2.1 V and short-circuit current of 42 nA. • Even without any external poling process, the fabricated TENG generated a maximum power density of 32.67 mW/m 2 .