Deposition, structure and properties of polyamide-CdSe-CdS composite material using sorption-diffusion method

Polyamide (PA) incorporated CdSe-CdS films were deposited using sorption-diffusion method. A single precursor - K2SeS2O6 was used as both sulfur and selenium source. In aqueous solution, SeS2O62− diffused into the polymer where it reacted with Cd2+ ions to form cadmium chalcogenide particles. Crystallinity of the composite material was analyzed via XRD and both CdSe and CdS were detected within the material at all deposition conditions of temperature and SeS2O62− - chalcogenization - exposure time. A complex surface speciation was obtained using XPS analysis. Formation of the protonated amide species was observed in combination with the adsorbed SO42− on the surface of the polymer confirming that SeS2O62− and its decomposition products hydrolyzed to form cadmium chalcogenides and H2SO4. A significant red shift in UV-vis spectrum was observed with the increasing chalcogenization time of PA, whereas Cd2+ solution temperature had very little effect on the apparent thickness and the optical properties of the composite materials. SEM surface analysis revealed sub-micron particles deposited on top of the PA-CdSe-CdS composite materials in continuous overlapping films, showing a possible dual crystal growth mechanism.