The purpose of this research is to optically characterize the band gaps of sulfide-based chalcogenides and copper oxide thin films. The analysis on the copper oxide thin films will view the effects of various annealing temperatures and the analysis of the chalcogenides will view the effects of silver doping on the thin films. Using UV-Vis spectroscopy, parameters such as the absorption coefficient and determined which then provide details on the optical band gaps of these various semiconductors. With a better understanding of the bandgap of these materials, the behavior can be better predicted in fields of nanoionics and photonics.