Splitting of luminescence bands of doped quantum dot ensembles in composite with polymers on the silver islands films obtained by chemical deposition method

The study demonstrates significant splitting of the impurity luminescence peak of cadmium sulfide quantum dots doped with copper and manganese ions in polymer composites on substrates with silver nanoparticles obtained by chemical deposition. The influence of polymer concentration and quantum dot type on the splitting is studied. 
Our results demonstrate that the probability of splitting occurrence and the spectral separation between the peaks are governed not by the optical density of the film or the size of the silver islands, but by the inter-island distance, highlighting the critical role of spatial arrangement in the collective optical response of the system.
It is hypothesized that the observed effect can be caused by coupling between the luminescent nanoparticles, which have long luminescence lifetimes, and the silver nanoislands, which act as nanoresonators.