General discussion Finally as a
In JIB-04 to the slightly improved QY value for CdSeTeS/ZnS1 QDs, the QY value for CdSeTeS/ZnS2 QDs dropped remarkably to 12%. However, the PL emission wavelength was the same for both sets of QDs. The conversion of the hydrophobic CdSeTeS/ZnS2 QDs to the water-soluble phase (l-cys-CdSeTeS/ZnS2), resulted in an appreciable increase in the PL QY to 21% and this is directly evident from the increase in the PL intensity as shown in Fig. 4D. From a scientific point of view, this phenomenon is intriguing because conversion of the hydrophobic QDs to water-soluble forms generally results in PL loss  and .
Fig. 5A and B shows the PL decay curves of the core and core/shell QDs where the hydrophobic QDs have been used as a reference for shoot study. While Table 2 lists the PL lifetime parameters. Comparing the average of each of the τ1 (longer lifetime), τ2 (intermediate lifetime) and τ3 (shortest lifetime) for the tri-exponential decay of the core and core/shell QDs, we observed that CdSeTeS1 QDs with a QY value of 92% decayed faster (9.7 ns) than the rest of the QDs ( Table 2). The drop in the QY for CdSeTeS2 (QY = 72%) resulted in a slower decay (15.4 ns) while CdSeTeS/ZnS1 (QY = 73%) produced a slightly faster decay (14.2 ns). CdSeTeS/ZnS2 QDs (QY = 12%) on the other hand, exhibited the slowest decay (22.0 ns). Hence, our data provides concrete evidence of the complimentary relationship between the PL QY and lifetime data trends.