Optical and structural properties of Sn and Ag-doped PbS/PVA nanocomposites synthesized by chemical bath deposition

In this work, Sn and Ag doped PbS/PVA nanocomposites, in three different concentrations were successfully prepared using the low-cost and simple method of chemical bath deposition (CBD). X-ray diffraction patterns confirmed the formation of the PbS cubic phase in all of the nanocomposites. FE-SEM images showed that PbS NPs are cubic in shape and the doping can alter the shape of grains. DLS analysis applied for solution NPs exhibited a 175 nm size distribution for PbS NPs and decreased by doping Ag and Sn to almost 100 nm and 110 nm, respectively. Optical absorption spectra showed the blue phenomena and the band gaps of Sn: PbS/PVA and Ag: PbS/PVA nanocomposites increased with adding Sn and Ag from 3.08 eV for pure PVA/PbS to 3.33 eV for Sn doped and 3.43 eV for Ag-doped samples. The nonlinear refractive index is decreased from 0.55 m² W^-1 for pure PVA/PbS to 0.11 m² W^-1 and 0.13 m² W^-1 for Sn and Ag-doped samples, respectively. Hence, doping Ag and Sn enhanced the optical sensitivity issue of nanocomposites and raised the optical resistivity. Collectively, our results can be useful in the design of linear and nonlinear optical devices such as sensors and optical switches and limiters.