Electrospun Benzimidazole: Poly(methyl methacrylate)\nNanofibers for Optoelectronic Applications

Organic benzimidazole nanocrystals\nwere incorporated inside the\npoly(methyl methacrylate) (PMMA) matrix using the electrospinning\ntechnique. The crystallization of the guest organic material inside\nthe host polymer was assessed by XRD analysis. Further morphology\nof the synthesized fibers was examined by using optical microscopy\nand SEM analysis. Raman analysis was utilized to determine the functional\ngroups present in the sample. The UV–vis and photoluminescence\n(PL) studies were performed to get an idea about the optical behavior\nof the prepared fibers. The second harmonic generation was demonstrated\nby the emission of green light through the Kurtz–Perry powder\ntechnique using a Nd:YAG laser excitation source with a wavelength\nof 1064 nm. Nonlinear absorption (NLA) behavior of benzimidazole (BMZ)-PMMA\nfibers was investigated by an open aperture Z-scan setup with a Q-switched\nNd:YAG laser as a source (532 nm, 9 ns, 10 Hz). Intensity-dependent\nNLA of the sample was assessed at various intensities (2.46–4.92\n× 10<sup>12</sup> W/m<sup>2</sup>), and corresponding NLA coefficients\n(β) were extracted from the data. The results demonstrate that\nreverse saturable absorption occurs at all intensities, which arises\ndue to sequential two photon absorption, which is confirmed from theoretical\nfitting and the curve plotted for β against input irradiance\n(<i>I</i><sub>0</sub>). The optical limiting action of the\nfiber sample was analyzed, and optical limiting threshold was calculated.\nA decrease in optical limiting with an increase in input laser intensity\nwas observed, and these values are lower in comparison to other optical\nmaterials. With all these findings, this report reveals that BMZ-PMMA\nfibers are potential candidates for effective optical limiting, which\nmay be employed in optoelectronic devices.