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

Highlights: • We investigated deposition of a single phase mixed CdSe–CdS on polyamide. • A single precursor – K₂SeS₂O₆ was used. • XRD analysis showed hexagonal CdSe and orthorhombic CdS phases. • Deposition mechanisms involved transient H₂SO₄ formation. - Abstract: 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