Molarity Influenced Interesting Electrochromic Optical Modulation Peak Shift in Nebulized Spray Deposited Mn3O4 Films

Abstract

Herein, we report the investigations on the electrochromic properties of nebulized-spray deposited Mn3O4 thin films in Na2SO4 aqueous solution as a function of molar concentration, for the first time. Phase analysis reveals that the films possess a tetragonal structure. From the Raman study, strong Mn2+ breathing vibration (in Mn–O) occurred in tetrahedral sites (of spinel Mn3O4). At 0.02 M, the film surface is covered with very-tiny particles with 84% highest optical transparency average. Both transmittance and absorbance related properties of electrochromic states are consider here, while introducing the notions of transmittance modulation (ΔT), absorbance modulation (ΔA), transmittance modulation efficiency (TME) and absorbance modulation efficiency (AME (or) coloration efficiency). When the concentration increases, the red shift was occurred at highest peaks of ΔT, ΔA, TME and AME with respect to the decrease in optical band gap. The maximum AME and TME of 25.064 cm2 C−1 (at 369.1 nm) and 17.542 cm2 C−1 (at 438.6 nm) were obtained for prepared samples. After the 100th cycle, the average AME (and TME) values in the UV and visible regions are decreases from 18.910 to 2.783 cm2 C−1 (2.884 to 1.060 cm2 C−1) and from 11.089 to 4.772 cm2 C−1 (11.346 to 4.684 cm2 C−1), respectively, indicating that the film is electrochromically active in the visible region even after the 100th cycle.