Stability and Fluorescence Quantum Yield of CdSe-ZnS Quantum Dots—Influence of the Thickness of the ZnS Shell

摘要

We investigated the correlation between the thickness of the ZnS shell of CdSe–ZnS quantumdots (QDs), the stability of the particles, and the fluorescence quantum yield. As a measure forstability, a new shell quality test was developed. This test is based on the reaction of the QDs withphotochemically formed thiophenol radicals and communicates an imperfect ZnS shell by a rapidand complete loss of fluorescence. The quantum yield increases from less than 5% for unshelledCdSe up to 50%, with an increase in ZnS shell thickness up to 0.6-0.8 nm. At the same time, theparticles become significantly more stable, as revealed by the shell test.