The structure analysis and optical performance of PVA films doped with Fe³⁺-metal for UV- limiter, and optoelectronics

A conventional casting technique was utilized to prepare the PVA/ Fe³⁺ composite samples with various weight levels (PVA:0.04 Fe³⁺, PVA:0.19 Fe³⁺, PVA:0.40 Fe³⁺, PVA:1.90 Fe³⁺ and PVA:4.00 Fe³⁺ wt%) of FeCl₃. Based on the influence of wt%, the structure of PVA changed to semi-crystalline material with a high disordered degree. According to the FT (Fourier transform), -IR and x-ray diffraction results indicate the interlinked of FeCl₃ with the hydroxyl group in the matrix. From Scherer calculation, the average crystallite size of composites is found to be declines from 2.287 nm to 2.086 nm and the strain increased to 0.097. The SEM results reveal that the addition of FeCl₃ particles is agglomerated over PVA surface and form a different distribution cluster. For the design of optoelectronic devices, the useful optical limitations were calculated from the transmittance and absorption spectra in the UV-vis-IR regions. From optical data it is noticed that the n (refractive index), E _d (transition strength), and S _o (oscillator strength) are increased, while the other parameters such as E _e (absorption edge), E _opt (energy gap), E _u (Urbach energy), E _o (average excitation energy), and λ _o (oscillator position), are decreased. Additionally, there are sub-levels were built in the energy gap which is clear in its smallest value. The present samples have special characteristics for UV-protector, in addition to their ability to use in optoelectronic purposes.