Photodarkening of blinking quantum dots is not governed by Auger recombination

TL;DR

This study investigates the cause of blinking in quantum dots and finds that it is not primarily due to Auger recombination, but involves a different three-step process of photoexcitation, trapping, and nonradiative decay.

Contribution

The paper provides experimental evidence challenging the assumption that Auger recombination governs quantum dot blinking, proposing an alternative mechanism.

Findings

Blinking dynamics are inconsistent with Auger process expectations.

Quantum dots cycle through photoexcitation, trapping, and slow decay in the 'off' state.

Size and intensity dependence do not match Auger recombination models.

Abstract

The observed intermittent light emission from colloidal semiconductor nanocrystals has long been associated with Auger recombination assisted quenching. We test this view by observing transient emission dynamics of CdSe/CdS/ZnS semiconductor nanocrystals using time-resolved photon counting. The size and intensity dependence of the observed decay dynamics are inconsistent with the those expected from Auger processes. Moreover, the data suggests that in the `off' state the quantum dot cycles in a three-step process: photoexcitation, rapid trapping and subsequent slow nonradiative decay.