Optical Band Gap Characterization Of Polymer Based Nanocomposite Thin Films

摘要

The nanocomposite solutions of carbon nanotubes/poly (methyl methacrylate) (CNTs/PMMA) were prepared using different weight percentage of CNTs, from 0 wt% to 3.0 wt% of PMMA in tetrahydrofuran (THF). The CNTs is physically dispersed in the polymer solutions using ultrasonicator for a specific sonication time along with mechanical stirring. When the black and uniform solutions were observed, the nanocomposite thin films of CNTs/PMMA were then produced by spin coating method using glass substrate. The resulted thin films were examined by scanning electron microscopy (SEM) in order to study the dispersion behavior of CNTs in polymer solution. The direct and indirect optical band gaps (E_g) were calculated by UV-Vis Spectroscopy and both direct and indirect band gap graphs were plotted. The optical gap width Eg of nanocomposite thin films was analysed from the linear part of plot (ahv)~x vs. hv. The well-dispersed CNTs in PMMA solution decreases the optical band gap along with the addition of CNTs, and the optimum sonication time gives the decreasing trend of optical band gap with the increasing wt% of CNTs.