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

TL;DR

This study demonstrates a simple synthesis of Ag-doped ZnS quantum dots and enhances their blue photoluminescence through UV photolysis and high-temperature, high-pressure treatments, improving their suitability for display applications.

Contribution

It introduces a straightforward co-precipitation method for ZnS:Ag,Al QDs and details step-by-step enhancement techniques for their photoluminescence.

Findings

PL intensity increased by 170% after UV photolysis

Further enhancement to 250% achieved with high temperature and pressure treatment

Crystallinity improvements correlated with PL enhancement

Abstract

Our results pertaining to the step by step enhancement of photoluminescence (PL) intensity from ZnS:Ag,Al 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,Al QDs was considerably weak and not suitable for any practical display application. Upon UV (365 nm) photolysis, the PL intensity augmented to ~170% and attained a saturation value after ~100 minutes of exposure. This is attributed to the photo-corrosion mechanism exerted by high-flux UV light on ZnS:Ag,Al QDs. Auxiliary enhancement of PL intensity to 250% has been evidenced by subjecting the QDs to high temperatures (200oC) and pressures (~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.