Controllable synthesis of monodispersed PbS colloidal quantum dots and their size regulation

Lead sulfide nanocrystals, also known as lead sulfide colloidal quantum dots (PbS CQDs), have a tunable bandgap, a large exciton Bohr radius and a wide size distribution. The high-quality PbS CQDs have shown excellent photoelectric properties in the field of infrared photodetectors. Monodisperse PbS CQDs can be successfully synthesized by hot injection method in solution, using elemental sulfur and lead oxide as reaction precursors. The synthesized CQDs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-Vis- NIR spectrophotometer. It is concluded that the PbS CQDs synthesized under the condition of 120°C and 90 min are truncated octahedrons. I- can further passivate the exposed (200) crystal plane when tetrabutylammonium iodide (TBAI) was used for ligand exchange. The prepared CQDs films can be applied to infrared photodetectors and solar cells. Finally, the particle size of CQDs was analyzed by Scherrer formula and the probability statistical model was proposed. The correction coefficient of the particle size of PbS CQDs related to the shape factor was summarized.