Plasmon-Enhanced Fluorescence of NIR-Emitting CdxHg1-xTe Quantum Dots by Ag Nanoprisms

Near-infrared (NIR)-emitting colloidal semiconductor nanocrystals (NCs) draw a lot of attention due to various fields of their potential application, such as bio-imaging, photovoltaics, photodetectors, light-emitting diodes, and optical amplifiers for telecommunication. Since they typically suffer from the partial loss of their fluorescence in a solid state, strategies to increase their quantum yields are of outstanding importance. One of the means to improve it is their coupling with structures exhibiting localized surface plasmon resonance (LSPR). As demonstrated for the visible range of light, plasmon-exciton interactions can enhance the photoluminescence (PL) of CdSe and CdTe NCs. In this work, the influence of the electromagnetic field of plasmonic silver NCs on the PL of CdxHg1-xTe NCs in the NIR region with a special emphasis on tuning the distance between these particle species is studied. In a series of samples prepared by a layer-by-layer deposition through polyelectrolytes, a 1.4-fold PL enhancement at a distance of 9-11 nm between the two layers is observed, while at any other separation emission quenching is a dominating effect. These findings corroborate well with theoretical predictions of an emission increase at these specific distances and can be applied to other types of plasmonic and emitting materials.