An improvement in chitosan film photoluminescence was observed after adding LiClO 4 . FTIR spectra, XPS, DFT calculations, and XRD measurements show an alteration of the Hbonds and an increase in the amorphous character of chitosan. PL spectra display a growth in intensity in the visible region along with the incorporation of lithium, signaling a possible rise in the population density of tail states and, consequently, better photon absorption, as observed from UV−vis measurements. A mechanism through aggregation-induced emission effect is proposed to explain the different results. Although this work establishes the relation between structural changes provoked by LiClO 4 incorporation and luminescence in the case of chitosan, we expect that the same approach could be generalized to similar polymeric structures.