Photoluminescence Intermittency and Photo‐Bleaching of Single Colloidal Quantum Dot

Abstract

Photoluminescence (PL) blinking of single colloidal quantum dot (QD)-PL intensity switching between different brightness states under constant excitation-and photo-bleaching are roadblocks for most applications of QDs. This progress report shall treat PL blinking and photo-bleaching both as photochemical events, namely, PL blinking as reversible and photo-bleaching being irreversible ones. Most studies on single-molecule spectroscopy of QDs in literature are related to PL blinking, which invites us to concentrate our discussions on the PL blinking, including its brief history in 20 years, analysis methods, competitive mechanisms and different strategies to battle it. In terms of suppression of the PL blinking, wavefunction confinement-confining photo-generated electron and hole within the core and inner portion of the shell of a core/shell QD-demonstrates significant advantages. This strategy yields nearly non-blinking QDs with their emission peaks covering most part of the visible window. As expected, the resulting QDs from this new strategy also show substantially improved anti-bleaching features.

A White Light‐Emitting Quantum Dot Complex for Single Particle Level Interaction with Dopamine Leading to Changes in Color and Blinking Profile

“…The single particle nature of WLE QDC (deposited on a glass cover slip) was demonstrated based on the blinking activity, that is, time‐dependent alteration between on state (emitting state) and off state (dark state) using CLSM under superresolution. This is a primary signature, of single luminescent nanocrystals, which distinguishes them from multiple nanocrystals . Figure E shows the superresolution representative image of the white colored particles as obtained from Figure D (iii).…”

“…In our case, the probability distributions of the events (on and off) could be fitted well by a truncated power law through a log–log plot extracted from the obtained data points for 40 single particles (Figure H,I), the details of which are described in the Experimental Section. It is to be mentioned here that the exponent of the power‐law distribution (known as α on and α off ) of the on and off events is an important parameter with regard to the luminescence behavior of a blinking single nanocrystal . Hence, any chemical reaction or physical interaction that alters the emission characteristics of a single nanocrystal may lead to change in the exponents (α on and α off ) and their ratio (α on /α off ) in the blinking statistics .…”

“…Chemical methods of suppression of blinking can also be considered to contain hint of the nature of the environment surrounding the emissive Qdot. Notably, the changes in the blinking statistics, especially the exponents of the on and/or off probability distribution, in the presence of an analyte could also be considered a characteristic useful in sensing.…”

“…Colloidal semiconductor quantum dot (Qdot) single particles provide an important option for sensing molecule and phenomenon at the highest resolution using light as the probe. [1][2][3][4][5][6][7][8][9][10][11][12] However, the performance is significantly impeded by intermittency in photoluminescence referred to as blinking. [1][2][3][4][5][6][7][8][9][10][11][12] Chemical methods of suppression of blinking can also be considered to contain hint of the nature of the environment surrounding the emissive Qdot.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] However, the performance is significantly impeded by intermittency in photoluminescence referred to as blinking. [1][2][3][4][5][6][7][8][9][10][11][12] Chemical methods of suppression of blinking can also be considered to contain hint of the nature of the environment surrounding the emissive Qdot. Notably, the changes in the blinking statistics, especially the exponents of the on and/or off probability distribution, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] in the presence of an analyte could also be considered a characteristic useful in sensing.…”