Comparative studies on the structural, morphological, optical, and electrical properties of nanocrystalline PbS thin films grown by chemical bath deposition using two different bath compositions

• PbS films for application in IR detector and solar control systems were prepared.
• Grain size effect on strain and lattice constant of PbS films were investigated.
• High-reflectance PbS film was obtained by choosing suitable molarities of solutions.
• The relation of the rms-surface slope parameter to reflectance was explained.
• Various properties of films of the two groups were compared and discussed.

High-quality lead sulfide (PbS) thin films were synthesized by chemical bath deposition from two baths with different compositions. One of them (bath-І) contained an aqueous solution of lead acetate, thiourea, sodium hydroxide, and the second (bath-ІІ) had additional triethanolamine. The introduction of triethanolamine reduced the grain size and increased the optical band gap of the PbS nanoparticles. The structure, morphology, and optical properties of the obtained films were investigated and compared with respect to the deposition time. X-ray diffraction data were used to obtain the crystallite size, lattice constant, and strain of the films. Atomic force microscopy results show that the roughness and rms-surface slope of the samples obtained from bath-I (PbS-I) were higher than those of bath-II (PbS-II) samples. PbS thin films with high reflectance (~61%) in the near-infrared region, which is important in our solar system, were obtained. The band gap, extinction coefficient, and refractive index of the samples were calculated. Furthermore, Raman analysis was performed and electrical properties of the samples were studied.