Analysis of optical linearity and nonlinearity of Fe³⁺- doped PMMA/FTO polymeric films: New trend for optoelectronic polymeric devices

Iron-doped polymethylmethacrylate (Fe³⁺/PMMA) films were deposited on FTO glass substrates. X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FT-IR) were applied to examine the structure of Fe³⁺/PMMA/FTO films with varying doping percentages of iron-ions. The obtained XRD diffraction results proved the uniform and semi-crystalline in nature of the tested samples. The vibrational modes of both metal-ions and host PMMA polymers were respectively observed at 450 and 980 cm⁻¹. The direct optical energy bandgaps for the proposed undoped and Fe³⁺-doped PMMA thin films were valued to be approximately 4.11, 4.1004, 4.094, 4.087, 4.07, 3.801, and 3.35 eV. The indirect energy bandgaps were 3.605, 3.58, 3.55, 3.504, 2.85, and 2.37 eV with increasing the Fe³⁺-contents, respectively. Moreover, the optical limiting of Fe³⁺/PMMA/FTO films was studied through red He-Ne and green diode lasers operating at 632.8 and 532 nm, correspondingly. Finally, Fe³⁺-doped PMMA/FTO composites are considered an excellent candidate for various optoelectronic devices.