A Influência dos Íons de Lítio: Caracterizações Eletroquímicas, Ópticas, Morfológicas e Estruturais de Filmes Finos de MoO3 e MoO3:Li+

Abstract

The study aims to analyze the optical, structural, morphological and electrochemical properties of thin films of molybdenum (VI) oxide and the changes that different concentrations of doping with lithium ions can cause in these films. The electrochromic films were obtained through the combination of two techniques: to obtain the solution, the sol-gel process was used and for its deposition at different speeds, the dip-coating technique was adopted. Since there are not many precedents for using this method for this oxide, the deposited liquid has undergone a heat treatment at a temperature of 300 ° C, in order to obtain the electrochromic films. Systematic studies were performed in order to obtain a better electrochemical response, varying parameters such as the thickness and the concentration of the dopant in the films. Through cyclic voltammetry, chronochoulometry and chronoamperometry measurements, the electrochemical changes in the films were analyzed, such as the process of color modification through intercalation and deintercalation of lithium ions. The morphological properties were analyzed using Atomic Force Microscopy (AFM), presented a difference in roughness between the films, the structural properties through X-Ray Diffraction, showing an amorphous structure in the films and, finally, the optical properties through the UV-Vis Spectroscopy, which showed a maximum transmittance difference of 14.28% for the thickest films. The obtaining of the results allowed necessary adjustments for the best concentration of dopant, in this case 5 µl of Li+, and thus improvements were observed in the electrochemical behavior of the films, with a greater charge storage, from 14.77 to 44.68 mC.cm-2, a desired property for the use of electrochromic films.