Effect of Annealing on Sol–gel-Deposited PZT Thin Films for Nano-generator Applications

The sol–gel method provides an effective route for the fabrication of Pb(Zr0.52Ti0.48)O3 (PZT 52/48) piezoelectric thin films, allowing for fine control over their composition, phase development, and microstructural features. In this research, the PZT (52/48) nanofilms were fabricated on FTO-patterned glass substrates via a spin coating process. The morphological characteristics of the resulting PZT nanofilms were assessed using an X-ray diffractometer, which revealed crystallite sizes ranging from 20.6 nm to 41.3 nm, depending on the annealing conditions, and showed the splitting of peaks at 2θ ≈ 42°−46° as (002), (200), confirming the presence of the tetragonality phase. Surface morphology was further examined through atomic force microscopy (AFM), providing insights into grain structure and roughness evolution. The average roughness of the thin film, determined after annealing at temperatures between 500 and 650°C, increases to 5.43, 6.52, 7.46, and 8.13 nm. Analysis was conducted using Raman spectroscopy to investigate the variations in peak positions, peak intensities, and the potential for phase transitions from rhombohedral to tetragonal with varying annealing temperature parameters. UV–Vis spectroscopy was utilized to study optical behaviour. Annealing the films from 500 to 650°C led to a reduction in the band gap from 3.54–3.41 eV. The prepared pressure-sensing PZT nanogenerator generates an output voltage of approximately 130 mV using a tapping force of approximately 0.02 kgf at a frequency of 20 Hz.