Poly(vinylpyrrolidone)-modification of sol-gel films for flexible piezoelectric energy harvesting systems

A crack-free and dense, yet thick lead lanthanum zirconium titanate (PLZT; P0.92L0.08Z0.65T0.35) film was achieved by single-step, non-repetitive spin-coating of PLZT sol-gel chemically modified with poly(vinylpyrrolidone) (PVP). Incorporation of PVP into the precursor solution could be highly beneficial for prohibiting cracks during the condensation reaction of spin-cast gel film and controlling the film thickness. Close examination by using optical microscopy, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy enabled compositional and structural characterization of PLZT films on both transparent sapphire and flexible plastic substrates before and after the laser lift-off process. Such dense and crack-free PLZT film with thickness ranging from 2.5 to 3.4 μm was successfully applied for fabricating flexible piezoelectric energy harvester. This study can be further extended to prepare other crack-free, dense piezoelectric films, thus offering a facile and robust pathway to the fabrication of the piezoelectric energy harvesting devices.