A free-standing Co: ZnO (CZO) doped PVA nanocomposite polymer system films (CZO-PVA NCPSFs) for optical sensing electronic devices

The casting aqueous solution technique was used to prepare Co: ZnO incorporated PVA nanocomposite polymer system films (CZO-PVA NCPSFs) with different wt % CZO nanopowders. Based on the Williamson-Hall equation, the values of crystallite sizes, lattice strains, dislocation densities, and stacking fault energies were found to be in the range of 27.13–72.59 nm, 4.08 × 10⁻⁵-1.63 × 10⁻³, 1.36 × 10¹⁵–1.89 × 10¹⁴ lines per m² and 3.82 × 10⁻³-1.87 × 10⁻³ for the pure CZO nanopowders and 3.70 wt% CZO films, respectively. The first direct-band gap bowing parameter decreased from 5.773 eV for pure PVA to 3.117 eV for 3.70 wt% CZO. The second direct band gaps were observed at 2.741, 2.523, and 2.413 eV for the 1.85 wt% CZO, 2.78 wt% CZO, and 3.70 wt% CZO films, respectively. The first values of indirect band gaps were observed in the range of 4.708 eV for pure PVA to 3.931 eV for 3.70 wt% CZO films. The second indirect values were observed in the range of 1.651 eV for 0.18 wt% CZO to 0.599 eV for 3.70 wt% CZO films. The limiting effect of CZO-PVA NCPSFs was also affected by the doping concentration of CZO nanopowder. The values of R_b, Q, and σ_DC parameters were found to be in the range 7.08 × 10⁷–3.89 × 10⁸Ω, 9.03 × 10⁻¹¹-6.03 × 10⁻¹¹ F, and 5.755 × 10⁻⁸-1.047 × 10⁻⁸ S/m for pure PVA and 3.70 wt % CZO films. Our results provide valuable insights into designing and optimizing CZO-PVA NCPSFs for optical sensing electronic applications.