A study of the optical band gap energy and urbach energy of fullerene (C60) doped PMMA nanocomposites

Abstract

Fullerene dispersion in a polymer matrix alters the values of band gap energy and Urbach energy of the nanocomposite. In the presented work, the influence of fullerene dispersion and polymer-fullerene interactions on the band gap energy and Urbach energy of poly (methyl methacrylate)-fullerene C60 nanocomposite has been studied by means of UV-Vis absorption spectroscopy. Pure and different doped films of gradually increasing concentrations were fabricated using solvent casting technique. Optical properties of these films were obtained from the UV-VIS absorption spectra, at normal incidence, over190-1100 nm spectral range. The optical absorption edge was described using the Tauc model. Band gap energy of the thin films was found using Tauc plot. The width of the band tails, known as Urbach tails, were evaluated to quantify the structural disorder. Optical characterization showed that average absorption and band gap energy decreased, while Urbach energy increased with the addition of fullerene C60