Single-precursor, one-pot versatile synthesis under near ambient conditions of tunable, single and dual band fluorescing metal sulfide nanoparticles

We present a simple and versatile method for the synthesis of high-quality size-controlled metal sulfide nanoparticles. A single compound (metal xanthate) is the precursor. A Lewis-base solvent is used to achieve a low reaction temperature of 50-150 °C, usually in air. Demonstrated with CdS, the precise control over the particle size (by regulating the temperature or the concentration) enables tuning the absorption and emission spectra of the particles. We also can control the relative intensity of the narrow (30-35 nm wide) excitonic emission (tunable in the range 430-480 nm with ∼2% fluorescence quantum efficiency) and the broad emission associated with deep surface traps (in the range 550-700 nm). Using the same precursor CdS/ZnS core/shell particles are produced with a high PL yield (∼14%).