The impact of iron concentration on the structural and optical properties of iron lead sulphide thin films

Abstract

The article reports on the synthesis of iron-lead sulphide (${\text{Fe}}_x{\text{Pb}}_{1-x}S$) thin films using the chemical bath deposition (CBD) technique. X-ray diffraction analysis confirmed that the deposited films were polycrystalline, exhibiting a strong (200) peak orientation. However, increasing iron incorporation led to a decrease in the average crystallite size from 47.4 to 22.9 nm. Scanning electron microscopy (SEM) revealed a variety of randomly distributed nanostructures across the films. Furthermore, the optical transmittance increased from 60 % to 80 % with an increase in iron concentrations, while the optical band gap varied from 1.86 to 2.25 eV. The optical analysis reveals that as iron concentration increases, the refractive index rises from 1.95 to 2.53. The real dielectric constant (Ɛᵣ) shifts from 3.76 to 6.48, while the imaginary dielectric constant (Ɛᵢ) changes from 0.03 to 0.13 respectively. These results indicate that the synthesized iron-lead sulphide thin films may be suitable for several optoelectronic applications.