Effect of the Thiol−Thiolate Equilibrium on the Photophysical Properties of Aqueous CdSe/ZnS Nanocrystal Quantum Dots

摘要: We study the effect of thiols on emission efficiency aqueous CdSe/ZnS core/shell nanocrystal quantum dots (NQDs). observe that impact thiol addition yields (QYs) is time-, concentration-, and pH-dependent. Further, we use a combination time-resolved spectroscopic methods to determine mechanism by which can cause either increases or decreases in QYs. Specifically, through transient absorption measurements, show improve passivation electron traps, increasing QYs at low concentrations. using nanosecond photoluminescence (PL), higher concentrations, hole traps are introduced reduce PL Last, pH-dependence control studies (e.g., 2-methyl thioethanol an NQD solution dodecanethiol hexane solution), demonstrate it ability generate thiolate sou...