LAUSR

Abstract Comparison of the absorption spectra of the ethanolic solution (3ppm) of some diethyl-3,4-diaminothieno[2,3-b]thiophene-2,5-dicarboxylate (TT amino ester) derivatives has revealed that the azo dye derivative compound 4 manifests smaller band gap and higher absorption maximum close to solar maximum wavelength. Very good adhesive thin films to glass substrates of the azo dye compound 4 have been successfully prepared by thermal evaporation technique. The optical spectral analysis of such compound film revealed three absorption transitions corresponding to the optical gap, the electron transition between impurity levels in band gap and the fundamental band gap (HOMO to LUMO π → π ⁎ transitions). Absorption, dielectric and dispersion parameters have been determined for as- deposited and gas treated films and discussed. This film manifested a fast response and high sensitivity toward iodine vapor with a reasonable recovery time indicating a reversibility of iodine adsorption process. In contrast, the film illustrated slow response and weak sensitivity toward HCl gas with irreversible adsorption process. Besides, the azo dye compound 4 solution manifests strong emissive properties that recommend it as promising candidate for fluorescence sensors.