Preparation of colloidal lead sulfide nanoparticles by laser ablation in water for optoelectronic devices applications

In present work, lead sulfide PbS nanoparticles NPs are synthesized by laser ablation of lead sulfide target in double distilled water using 0.532 and 1.064 μm wavelengths. The transmission electron microscopy TEM, atomic force microscopy AFM and X-ray diffraction XRD were used so as to determine the shape, size, distribution, and structure of the nanoparticles prepared with different laser wavelengths. X-ray diffraction results confirmed that the lead sulfide nanoparticles crystallized in the cubic phase and presents a preferential orientation along (200) plane and with no observation of any incomplete phases. Optical band gap values of 1.9 and 2eV for the lead sulfide nanoparticles were determined by UV-Vis absorption measurements. It was found that the morphology and size of PbS NPs depend on laser wavelength. To check the possibility of synthesised nanoparticles for optoelectronic devices, a novel type of solution-processed hetero-junction photodetector, prepared by drop cast film of colloidal lead sulfide nanoparticles NPs onto n-type single crystal silicon wafer was demonstrated. The effect of laser wavelength on the electrical characteristics and photosensitivity of p-PbS/n-Si heterojunction has been investigated.