Enhancing UV light sensitivity of PVP polymer by doping chromium trioxide via the electrospun solutions

Abstract

Herein, chromium trioxide (Cr₂O₃) doped Polyvinylpyrrolidone (PVP) nanofibers with high crystallinity and UV light sensitivity are successfully grown onto the glass substrates by electrospun deposition at room temperature. The effect of Cr₂O₃ concentration on the morphology, structure, and photoluminescence properties of the as-fabricated PVP nanofibers is examined. With the increase in doping concentration of Cr₂O₃ (i.e., 1, 2 and 3 %), the direct band gap of PVP nanofibers is reduced to 4.05, 4.01, and 3.85 eV, respectively. XRD and FE-SEM results manifest that the crystallinity and diameter of the nanofibers are dependent upon Cr₂O₃ concentration, i.e., the mean diameter decreases from 600 to 200 nm. Photoluminescence spectra indicate higher UV emission upon the addition of Cr₂O₃, with greater emission near the band edge for thinner nanofibers. A possible mechanism for the formation of PVP/Cr₂O₃ nanofibers is addressed in detail. Furthermore, it is found that the sensitivity of the as-fabricated PVP/Cr₂O₃ detector to UV-light emission strongly depends on Cr₂O₃ concentration, i.e., good responsivity (2.257 A/W) and specific detectives (9.8 $\times$ 10¹² cm Hz^1/2/W) at a Cr₂O₃ concentration of 2 % are achieved at a wavelength of 454.1 nm, besides recording the lowest rise and fall times.