Effect of heat treatment on the photoluminescence of CdS nanocrystallites in cadmium-rich organic Langmuir Blodgett matrix

► Interaction of Cd-rich organic LB matrix with CdS nanocrystallites investigated. ► Absorption and luminescence correlated with microstructure of composite multilayers. ► Suppression of surface and bulk defects of nanocrystallites due to Cd2+ enrichment. ► Strong enhancement of blue emission from nanocrystallites on vacuum heat treatment. ► Excitonic and defect emissions analyzed to propose an energy level diagram.