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Lead sulphide (PbS) nanocrystalline thin films were deposited on silica glass substrate by chemical bath deposition method at a bath temperature of 70 °C from six different complexing agents. Different characterization techniques were employed to investigate the effect of applying various complexing agents on the growth mechanism and physical properties of PbS thin films. The XRD results revealed that all the deposited thin films shows a face centered cubic crystal structure however, the preferred orientations of the crystallites varied along the (111) and (200) planes with complexing agents. It was also observed that the complexing agents had a strong influence on the average crystalline size, microstrain and dislocation density of the PbS thin films. The EDX study confirmed that complexing agents had a noticeable effect on the stoichiometry of PbS thin films. The optical absorption spectroscopy study revealed that the optical band gap of the PbS thin films found in the range of 0.77–1.34 eV. The room temperature photoluminescence study verified that irrespective of complexing agents all the deposited thin films experienced emission at 761 nm. Raman studies showed a strong peak around 134 cm −1 irrespective of complexing agents. [ABSTRACT FROM AUTHOR]

Lead sulphide (PbS) nanocrystalline thin films were prepared by chemical bath deposition route from two different chemical baths. The first bath (bath-A) was synthesized by varying the volume of ammonia to study the effect of bath pH, while the second bath (bath-B) was complexed by potassium hydroxide and the effect of lead molar concentrations were investigated. The X-ray diffraction analyses confirmed that all deposited thin films from the two baths had face centered cubic crystal structure. The XRD results also verified that the crystalline size increased from 25 to 40 nm when lead molar concentration decreased to 0.1 M. The HRTEM images showed that the grains are grown along different planes which confirmed a typical polycrystalline nature of the deposited PbS thin films from both chemical baths. The elemental analyses were carried out by EDX and confirmed the formation of PbS compound. The optical absorption study showed that the lowest optical band gap of 0.81 eV was estimated from bath-B at 0.1 M lead concentration, whereas, a highest band gap of 1.57 eV was found from bath-A. The transmittance study verified that the transmittance was increased with the wavelength and the maximum transmittance was measured around 24.51% for pH 10.5. The photoluminescence study revealed that the PbS thin film exhibited a broadband emission spectra from 410 to 625 nm regardless of bath pH and lead concentration. The dc-two point probe measurement verified that the electrical properties of the PbS thin films were considerably changed by bath pH and lead molar concentrations. The room temperature resistivity of the thin films found in the order of 104 Ω cm. [ABSTRACT FROM AUTHOR]

In the present report, undoped and tin (Sn)-doped lead sulfide thin films were synthesized via chemical bath deposition method. The effects of Sn molar concentration on the optical, structural, and morphological properties were systematically studied. The concentration of Sn in the chemical bath was characterized by the ratio of [Sn+2]/[Pb +2] and varied from 0 to 15 at.%. Both doped and undoped thin films were polycrystalline in nature with a face-centered cubic crystal structure; however, the preferred orientations of the crystallites were varied along the (111) and (200) planes with Sn-doping concentration. The X-ray powder diffraction results also showed that peak intensities and the crystalline size were decreased with increasing Sn concentration. The lattice constant varied with Sn concentration and found in the range of 6.020 to 5.944 Å. The variation of Sn concentration in PbS:Sn thin films were confirmed by energy dispersive X-ray analyses study. The scanning electron microscope and atomic force microscopy studies revealed that Sn doping had a critical role on the surface roughness and morphology of the PbS:Sn thin films. The optical band gap study showed that the band gap of PbS:Sn thin films were engineered from 0.676 to 1.345 eV because of incorporation of Sn+2 ions via cost-effective chemical route. Room temperature photoluminescence spectra showed a well-defined peak at 427 nm and shoulders at 405 and 462 nm for all Sn-doped and undoped PbS samples. [ABSTRACT FROM AUTHOR]

• Triethylamin (Et 3 N) used as a complexing agent to prepare PbS thin film. • AFM micrographs shows the films were composed of mixed shape grains. • The EDX analysis was confirmed the presence of Pb and S elements. • The estimated band gap found in the range of 1.57–1.35 eV. • The resistance of the thin films found in the order of 104 Ω. Chemical bath deposition (CBD) route was used to prepared lead sulphide (PbS) thin films on glass substrates by using triethylamin (Et 3 N) as complexing agent. The influence of varying the concentration of Et 3 N on the electrical, morphological, photoluminescence and structural properties of the deposited thin films were studied. The XRD results justified that independent of Et 3 N molar concentration the crystalline preferentially growth along the (1 1 1) plane. However, the intensities of the (1 1 1), (2 0 0) and (2 2 0) planes were improved as the Et 3 N molar concentration increased. The XRD study promoted that Et 3 N concentration had visible effect on the dislocation density and other structural parameters of the synthesized PbS. The AFM study revealed that both the average roughness and root mean square had direct relation with Et 3 N concentration. The optical study revealed that all the deposited thin films had high reflectance in the IR region. The optical band gap calculated from Stern relation was estimated in the range of 1.57–1.35 eV. The photoluminescence spectra showed well-defined peak at 628 nm for all PbS thin films and the emission intensity directly affected by the crystalline size. The resistance of the thin films found in the order of 104 Ω and had inverse relations with Et 3 N molar concentrations. [ABSTRACT FROM AUTHOR]

• Tartaric acid used as a complexing agent to prepare n -type PbS films. • The presence of Pb and S elements confirmed in the PbS films. • Band gap estimated in the range of 1.02 eV–0.73 eV. • Conductivity of the thin films found in the order of 10−2 (Ω cm) − 1. • Film thickness affected the physical properties of PbS films. Tartaric acid used as a complexing agent to synthesized crystalline lead sulphide thin films on microscope glass via chemical route. The influence of varying the film thickness on the electrical, morphological, photoluminescence and structural properties of the deposited material were studied by employing different techniques. The X-ray diffraction (XRD) study established that the prepared films had face centered cubic crystal structure irrespective of film thickness, however, their crystalline preferentially growth along the (111), (200) and (220) planes. The XRD study also promoted that film thickness had visible effect on the dislocation density and other structural parameters of the synthesized PbS film. The energy dispersive X-ray analysis study confirmed the presence of Pb and S elements in the prepared samples. The optical band gap calculated from Tauc relation was estimated in the range of 1.02 eV to 0.73 eV. Furthermore, dielectric constant, linear optical susceptibility and the refractive index of the films were estimated systematically. The presence of various functional groups were confirmed by Fourier transform-infrared spectroscopy analyses. The prepared films conductivity estimated in the order of 10−2 (Ω cm) − 1 and had direct relations with film thickness. The hot probe measurements verified that the deposited PbS films are n-type semiconductors. [ABSTRACT FROM AUTHOR]

Experimental and computational methods were employed to study the effects of gallium (Ga) doping on the structural and electronic properties of lead sulphide (PbS). Chemical bath deposition method was used to prepare Ga doped and undoped PbS at a deposition temperature of 80 °C and a pH of 11. The X-ray diffraction results confirmed that the prepared Ga doped and undoped PbS had face centered cubic crystal structures with preferential orientations along the (111) plane. The experimental results further revealed that Ga doping had a considerable effect on the structural parameters and optical band gap of PbS. The density functional theory calculated electronic structure further confirmed that Ga doping can cause Fermi level pinning in PbS by introducing a gap state between the conduction and valence bands. In addition, the band structure calculations revealed that PbS is a direct band gap semiconductor with its Fermi level lying exactly in between valance and conduction bands. All the experimental and computational results in the present work established that Ga doping had a significant effects on the structural and electronic properties of PbS. [ABSTRACT FROM AUTHOR]