Facile synthesis and step by step enhancement of blue photoluminescence from Ag-doped ZnS quantum dots

Our results pertaining to the step by step enhancement of photoluminescence (PL) intensity from ZnS:Ag,AI quantum dots (QDs) are presented. Initially, these QDs were synthesized using a simple co-precipitation technique involving a surfactant, polyvinylpyrrolidone (PVP), in de-ionised water. It was observed that the blue PL originated from ZnS:Ag,AI QDs was considerably weak and not suitable for any practical display application. Upon UV (365 nm) photolysis, the PL intensity augmented to similar to 170% and attained a saturation value after similar to 100 min of exposure. This is attributed to the photo-corrosion mechanism exerted by high-flux UV light on ZnS:Ag,AI QDs. Auxiliary enhancement of PL intensity to 250% has been evidenced by subjecting the QDs to high temperatures (200 degrees C) and pressures (similar to 120 bars) in a sulphur-rich atmosphere, which is due to the improvement in crystallanity of ZnS QDs. The origin of the bright-blue PL has been discussed. The results were supported by X-ray phase analysis, high-resolution electron microscopy and compositional evaluation. (C) 2011 Elsevier Inc. All rights reserved.