Photoluminescence investigations and thermal activation energy evaluation of Fe3+-doped PVA films

Abstract

In this work, we study the inclusion mechanism of Fe 3? ions in a polyvinyl alcohol (PVA) matrix. Pure and Fe 3? -doped PVA films, using FeCl 3 solution, are prepared by a solution casting method. The effect of Fe 3? doping on the photoluminescence (PL) behavior of PVA is investigated in the temperature range from 10 to 300 K. The PL intensity is found to decrease as the temperature increases for the samples slightly doped. This behavior is attributed to the phonon diffusion by the photo-created electron-hole pairs. However, this behavior is completely inverted when the content of Fe 3? increases. The first author has already published a work discussing the possible explanations of such a behavior where the PL intensity increases with temperature. This paper is devoted to study the thermal activations energy and its variation with doping. Therefore, the PL integrated intensity as a function of 1/T is simulated by the Arrhenius model for the samples whose PL intensity decreases with temperature. However, for the other samples, a model of two activation energies is used. The gap energy values and the PL spectra of all samples at 300 K were used to justify the suggested transitions.

Photoluminescence emission of a stable and well‐dispersed unsaturated polyester‐co‐rare‐earth complex

“…Fifty grams of UPR monomer [RE(MAA) 3 Phen (where RE represents Eu 31 or Tb 31 ; REX)], with different mass fractions (2,5,8,12, and 17 wt %) and trace amounts of cobalt bis(2-ethyl hexanoate) as an accelerator, were added to a 100 mL reactor in proper order, and then, MEKP was added. After the mixture was thoroughly and uniformly mixed and vacuum-treated at room temperature for 5 min in a vacuum oven, the rare-earth polymer UPR-co-RE(MAA) 3 Phen (URP-co-REX) was prepared; then, the film was scratched and cured on a film-blowing machine (Elcometer 4340 automatic film applicator).…”

“…The URP-co-REX films were prepared after curing with the action of the catalysis of catalyst when different concentrations of REXs (2,5,8,12, and 17 wt %) were added to UPR monomer. Then, the fluorescence emission intensity of the aforementioned films was measured under the optimum excitation wavelength (k ex ); at the same time, plots were obtained (as shown in Figure 4) where the relative fluorescence intensities of the emission peaks at 617 nm of Eu 31 and 544 nm of Tb 31 were plotted as the ordinate, and the added amounts of the complexes were plotted as the abscissas.…”

“…REPLAs with doping type are prepared by the dispersion of REXs into polymers through physical blending, such as melt blending and solution mixing. Doping not only enhances the stability of REXs but can also improve the fluorescence properties of REXs . Wolff and Pressley first introduced europium (Eu 3+ ) tris [4,4,4‐trifluoro‐ l ‐(2‐thienyl)‐1,3‐butanedione] into poly(methyl methacrylate) to prepare rare‐earth polymer fluorescence materials.…”

“…Doping not only enhances the stability of REXs but can also improve the fluorescence properties of REXs. 4,5 Wolff and Pressley 6 first introduced europium (Eu 31 ) tris [4,4,4-trifluoro-l-(2-thienyl)-1,3-butanedione] into poly(methyl methacrylate) to prepare rare-earth polymer fluorescence materials. De Souza et al 7 found that three fluorescence colors, red, green, and yellow, were achieved by the doping of Eu 31 and terbium (Tb 31 ) complexes into polystyrene.…”