Microstructure Study and Linear/Nonlinear Optical Performance of Bi-Embedded PVP/PVA Films for Optoelectronic and Optical Cut-Off Applications

Abstract

Hybrid polymer films of polyvinyl pyrrolidone (PVP)/polyvinyl alcohol (PVA) embedded with gradient levels of Bi-powder were prepared using a conventional solution casting process. XRD, FTIR, and SEM techniques have been used to examine the micro/molecular structure and morphology of the synthesized flexible films. The intensities of the diffraction peaks and transmission spectrum of the PVP/PVA gradually declined with the introduction of Bi-metal. In addition, filler changes the microstructure surface of the pure film. The modification in the microstructure leads to an enhancement in the optical absorption characteristic of the blend films. The indirect allowed transition energy was calculated via Tauc’s and ASF (Absorption Spectra Fitting) models. The decrease in the hybrid film’s bandgap returns to the localized states in the forbidden region, which led the present films to be suitable for photo-electric, solar cell, etc., applications. The relation between the transition energy and the refractive index was studied. The enhancement in the refractive index with Bi-metal concentrations led to use the as-prepared films in optical sensors. The rise of Bi-metal concentrations leads also to the improvement of the nonlinear susceptibility and refractive parameters. The optical limiting characteristics revealed that the higher concentration dopant films reduce the light transmission intensity which is appropriate for laser attenuation and optical limiting in photonic devices. The results suggest that hybrid films are promising materials in a wide range of opto-electronic applications.

Optimization of the glass transition temperature of polyvinyl pyrrolidone/polyacrylamide blend films using response surface methodology

“…The determined energy band gap values of the samples are tabulated in Table 5, and it is seen that the energy band gap of the optimized blended films is lower than that of the parental polymers. The decrease in the optical energy band gap of the polymer blends could be attributed to the increase in the defects and vacancies, causing the formation of localized energy states in the forbidden energy band gap 52 . This innovative finding of tailoring the bandgap of PVP and PAM via blending is very useful for building optoelectronic devices.…”

“…Conversely, the optimized blended film transmittance is less than 75% in visible–near infrared regions. This modification of optical transmittance by combining PAM and PVP powders is associated with the presence of interactions between the parental polymers (i.e., inter‐chain hydrogen bonding between the PVP carbonyl and PAM amide groups), 52 implying that PAM and PVP are miscible, and the optimized blended films could be considered for novel optoelectronic applications. Additionally, the absorbance spectra of both the parental polymers and optimized blended films (Figure 7a) indicate substantial UV absorptions resulting from inter‐band electronic transitions in both the parental polymers and optimized blended films 24 .…”

“…Additionally, the absorbance spectra of both the parental polymers and optimized blended films (Figure 7a) indicate substantial UV absorptions resulting from inter‐band electronic transitions in both the parental polymers and optimized blended films 24 . The optimized blended film, on the other hand, has an absorption edge that is red‐shifted to longer wavelengths as a result of the interactions between the polymers, that is, the formation of charge transfer complex between carbonyl groups or tertiary nitrogen atoms attached to the amide bond of PVP with the amide groups of PAM, which induce localized energy states in the forbidden energy gaps, leading to a decrease in the optical energy band gap of the optimized blended films 52 . The formation of charge transfer complexes between PVP and PAM in the optimized blended films is characterized by the shifting of the optical absorption spectra of the optimized blended films in the wavelength range 240–260 nm, as well as the shifting of the absorption band in addition to the broadening of the absorption band in the UV–visible region of the spectrum.…”

“…The decrease in the optical energy band gap of the polymer blends could be attributed to the increase in the defects and vacancies, causing the formation of localized energy states in the forbidden energy band gap. 52 This innovative finding of tailoring the bandgap of PVP and PAM via blending is very useful for building optoelectronic devices.…”

Effect of Ag/CuS nanoparticles loading to enhance linear/nonlinear spectroscopic and electrical characteristics of PVP/PVA blends for flexible optoelectronics

“…Similarly, Ali showed that Bi-doping in PVP/PVA blend led to E u increasing. 57 The E u results explain obviously the optical bandgap shrinkage of PVP/PVA blend. As a novel result of this study, the optical bandgap of blank PVP/PVA could be tailored to match new optical applications.…”