Structural, Linear, Nonlinear, and Optoelectrical Properties of PVA-PVP:Er Blend Films for Optical Device Applications

PVA-PVP blend films filled with various concentrations of Er (0.16, 0.40, 0.80, 1.58, and 3.125 wt %) were prepared using the solution-casting method. X-ray diffraction confirms the crystalline nature of PVA-PVP films due to the Er filler. The morphology of PVA-PVP films exhibits particle agglomeration and cluster formation with Er incorporation. The Raman spectra suggest possible modes of interaction between erbium ions and reactive functional groups (hydroxyl and carbonyl groups) in the PVA-PVP blend. Optical studies revealed a redshift in the absorption edge, reducing the optical bandgap from 3.65 to 3.15 eV due to the creation of localized states within the forbidden gap by Er3+ ions. The increase in Er content in PVA-PVP blend films shifts the refractive index from 2.292 to 2.402. The optical dispersion parameters of PVA-PVP blend films were strongly affected by Er3+ ions. The nonlinear optical and optoelectrical parameters were enhanced with the Er content in the PVA-PVP host matrix. The notable reduction in the optical band gap, accompanied by significant changes in the nonlinear optical and optoelectrical properties of PVA‑PVP:Er films, suggests their potential applications in optical devices.