Blinking suppression and intensity recurrences in single CdSe-oligo(phenylene vinylene) nanostructures: experiment and kinetic model

Abstract

We report time-resolved single molecule fluorescence imaging of individual CdSe quantum dots that are functionalized with oligomeric conjugated organic ligands. The fluorescence intensity trajectories from these composite nanostructures display both a strong degree of blinking suppression and intensity fluctuations with characteristic recurrence times on the order of 10-60 s. In addition, fluorescence decay rate measurements of individual hybrid nanostructures indicate significantly modified non-radiative quantum dot decay rates relative to conventional ZnS-capped CdSe quantum dots. We show that a modified diffusive reaction coordinate model with slow fluctuations in quantum dot electron energies (1S(e), 1P(e)) can reproduce the experimentally observed behaviour.

Blinking Kinetics of Single CdSe/ZnS Nanocrystals by Photon-Counting Statistics at High Temporal Resolution

“…In terms of statistics, these time constants imply that 5,208 and 384 photons can be counted for a unit second as the fluorescence intensities of "on" and "off" states. Figure 4(b) strongly demonstrates that emissions of single NCs flow between two levels ("on" and "off" states) contrary to the previous reports of continuous distribution in emission intensity [18,19].…”

“…Verberk et al suggested a charged "on" state in terms of trap depth [12]. Extending the prolonged "on" state to a three-state model, recent reports [18,19] have suggested that emission states of single NCs are governed by not two levels ("on" and "off") but numerous intermediate levels of continuous distribution. However, we noted that the temporal resolutions of these previous studies were limited to 10-100 ms/bin.…”

Structural and optical properties of electrodeposited Cd0.7Zn0.3Se thin films: Effect of annealing

“…Since last two decades, semiconductor nanoparticles have attracted considerable attention because of their size dependent electronic properties arising from the quantum confinement of electron [1][2][3][4][5][6][7]. II-VI semiconductor materials are recently more important for the optoelectronic devices as well as solar cells fabrication process.…”

Non‐Blinking Semiconductor Colloidal Quantum Dots for Biology, Optoelectronics and Quantum Optics

“…[32] This pioneering work concerning the passivation of electron surface traps by electron-donating groups was extended to conjugated organic ligands oligo(phenylenevinylene). [33] In this work, lifetime time-resolved measurements showed that the blinking reduction comes from a reduction of the lifetime of the electron-hole pair. Since the carriers of the excited electron hole pair have less time to cross the shell of the nanocrystal, blinking is reduced.…”