Synthesis and characterization of lead sulfide thin films by coumarin assisted CBD method

Coumarin which is a natural substance found in many plants is an organic chemical compound. In this study, we investigated the effects of coumarin adding during the growth of lead sulfide (PbS) thin films by chemical bath deposition (CBD). It was found that significant improvements were observed in the optical and structural properties of the films coated in the presence of coumarin. X-Ray diffraction, UV-vis spectrophotometry and scanning electron microscopy were used to systematically investigate the effect of coumarin on the characteristic properties of the PbS films. X-ray diffraction measurements have revealed that the increasing of coumarin content caused the decreasing the crystallite size of the films. On the other hand, UV-vis analysis showed that the band gap value of the coated samples increased from 1.80 eV to 2.53 eV by changing additive content from 0 to 4%. Also, UV-vis spectra exhibited that the transmittance of the samples varied between 37 and 50%. Further, surface roughness measurements showed that film morphology was influenced by the coumarin content. The results show that coumarin assisted growth of PbS nanostructures is a promising way to improve its physical properties.