Development of SnS/PVP core/shell quantum dots with tunable color emission synthesized by microwave heating

Tin sulfide (SnS) is an earth-abundance material of non-toxic nature compared to commercially available quantum dots (QDs). Herein, a novel strategy is reported to improve the spectral tunability and stability of SnS/polyvinylpyrrolidone (PVP) core/shell QDs via microwave irradiation synthesis. Although PVP is used as a capping agent and passivating ligand for SnS QDs, as reported elsewhere, we take advantage of its polarity that allows good interaction with microwave irradiation, which impacts the nucleation and growth of SnS QDs. Furthermore, the amount of PVP in the precursor solutions controls the surface states and color purity of the QDs, and the obtained SnS/PVP QDs exhibit color-tunable emission light from blue to orange. The photoluminescence quantum yield reached the highest reported for SnS QDs, whereas 50% of their fluorescence intensity was maintained after 1-year storage at daylight. This approach provides a synthetic route to produce tunable and efficient colloidal QDs.