Blinking Behavior of CdSe/CdS Quantum Dots Controlled by Alkylthiols as Surface Trap Modifiers

The blinking behavior of single quantum dots (QDs) is an intrinsic drawback for some biological and photoelectric applications that rely on single-dot emission. Some studies demonstrate that the blinking behavior of QDs is mainly attributed to nonradiative recombination processes associated with traps at the nanocrystal surface. In this study, we systematically investigated the effects of surface ligand alkylthiols on the blinking of CdSe/CdS QDs prepared in the organic phase and observed that the blinking of CdSe/CdS QDs was significantly dependent on the annealing time and structure and concentration of alkylthiol ligands. In the optimal conditions, we prepared thiol-modified CdSe/CdS QDs with a “nonblinking” fraction up to 83%. The mechanism of the blinking suppression was mainly attributed to modifying surface traps of QDs with alkylthiols. In this modification, the decomposition of alkylthiols can slowly release activated “S” under high temperature. Then the activated S can bind to surface traps of QDs, which induces a secondary growth of the core/shell QDs coupled with surface reconstruction and the efficient suppression of the blinking. The method described here can be used to suppress the blinking of other QDs