Quantum Dot Blinking Suppression

QD State

ON — bright exciton

On-time fraction

100%

Blink events

Photons emitted

Ionization rate

0 s⁻¹

Shell & Surface

CdS shell thickness 1.5 nm

Surface trap density 1.0×

Excitation

Pump rate 14 /s

Simulation speed 1.0×

How it works

A colloidal quantum dot's photoluminescence intermittency ("blinking") is driven by Auger-assisted photoionization: when the dot briefly holds a biexciton or a trapped charge, three-body Auger recombination can eject the extra carrier into a surface trap, leaving the dot singly charged (a trion). A charged dot decays almost entirely non-radiatively (fast Auger recombination of the trion), switching photon output OFF until the trapped carrier returns and neutralizes the core — switching it back ON.

The ionization rate is modeled as a tunneling-limited rate through the shell barrier, scaled by surface trap density and excitation rate:

k_ion = k0 · ρ_trap · exp(−d_shell / λ) · (R_pump / R_ref)
k_neutral ≈ constant (trap detrapping rate)
P(ON) = k_neutral / (k_neutral + k_ion)   [steady-state on-fraction]

Shell thickness d — a thicker CdS/ZnS shell exponentially suppresses Auger ionization by pushing the trap-bound carrier's wavefunction overlap with the core toward zero (tunneling decay length λ). This is the real mechanism behind "giant-shell" non-blinking quantum dots used in single-molecule imaging.
Surface trap density — poorer surface passivation (more dangling bonds / ligand defects) raises the ionization channel rate linearly.
Pump rate — higher excitation intensity increases the biexciton/charging probability per absorption cycle, raising k_ion.
The core glows dim red-orange and the trace drops to baseline while OFF (trion state, dark); it flares bright yellow-white while ON (neutral exciton, radiative).

Real-world relevance: blinking-suppressed ("non-blinking") quantum dots are used as single-molecule fluorescent tags in super-resolution microscopy and long-duration cell tracking, where every dark period is a missed detection event.

Core (neutral, ON) Shell (CdS/ZnS) Emitted photon

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.

Emission intensity trace