Azothiophene dyes nanotubes structure based thin films: Synthesis, structural and optical characterization toward application in dye-sensitized solar cells

A novel series of organic compounds containing azothiophene moiety have been synthesized. The thin films of these dyes have been prepared using a spin coating technique. The structure formation of the films has been studied using Fourier transform infrared, field emission scanning electron microscope and X-ray diffraction patterns. The synthetized dyes were characterized using spectral and elemental analysis. The structure investigation of azothiophene dyes thin films showed that the films have nanotubes structure. The optical properties of thin films were investigated using spectrophotometric measurements of the transmittance and reflectance of films in the spectral range 200 → 2500 nm, from which optical constants were calculated. The optical band gap was found to vary from 2.35 to 3.06 eV depending on the substitution patterns and substituent nature conjugated with the azothiophene moiety.