Controlled deposition of oriented PbS nanocrystals on ultrathin polydiacetylene templates at the air-solution interface

Lead sulfide nanocrystals with well-defined structure and orientation were obtained on ultrathin polydiacetylene (PDA) substrates, forming a unique hybrid functional material comprised of linear arrays of size-quantized semiconductor nanocrystals that are connected via conjugated polymer strand nanowires. The deposition was carried out at the liquid-gas interface by reacting aqueous solutions of PbCl₂ with controlled amounts of H₂S gas. Following nanocrystal deposition, the samples were transferred onto solid substrates using the Langmuir-Schaffer technique and characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and electron diffraction. AFM showed that the Pb²⁺ concentration is the main parameter that affects the growth. TEM and electron diffraction indicated that the nanocrystals are aligned with the linear PDA film, with a uniaxial orientation relationship in which the <110>_PbS direction is parallel to the linear direction of the polymer substrate.