Enhanced Photostability of Core/Shell Quantum Dots under Intense Blue Light Irradiation through Positive Photoaging Mechanism

Abstract

Photostability of semiconductor core/shell quantum dots (QDs) has historically been perceived as intricate and unpredictable. Notably, the long-term luminescence stability of QDs under light exposure does not seem to consistently correspond with their characteristics in the absence of light. In this study, we propose a positive photoaging mechanism of QDs, integrating both ligand/shell-induced photobrightening and surface photo-oxidation, to deal with the photostability nuances. When QDs are subjected to higher energy light, their photobrightening and photodarkening conjointly determine the photostability. Enhanced photostability may not be simply attributed to a thicker shell or the presence of ligands. When adjusted with an optimal shell thickness and supplemented with negatively charged ligands, QDs exhibit enhanced photostability in both solvents and polymers.

Macroscopic Discolorization in Quantum Dot Color Converters for Microdisplay Applications

“…An alternative approach such as embedding QDs in crystalline structure may also enhance the photostability, while it should carefully adjust the colloidal stability of QDs in polymer-based matrix. On the other hand, the use of neutron or positive-charge ligands to mitigate the detachment of ligands, it is possible to better anchor the ligands to the surface, preventing them from being repelled by negative charges and thus maintaining the photostability of the QDCCs …”

General Strategies for Preparing Hybrid Polymer/Quantum Dot Nanocomposites for Color Conversion

“…QDs without proper protection are susceptible to oxidation, leading to structural degradation and decreased fluorescence intensity [29]. Our recent findings suggest that even a polymer matrix may offer only temporary protection against the oxidation process [30,31]. Rather than dealing with the complex photochemical reactions occurring at the QD surface, an alternative approach involves overcoating with an inorganic layer to inhibit QD oxidation [32,33].…”