Suppressed Blinking and Pure Single-Photon Emission in Near-Infrared InAs Colloidal Quantum Dots with Strong Exciton Confinement

Abstract

Colloidal quantum dots (QDs) have emerged as potential single-photon emitters for quantum information processing due to their high color tunability and scalable production. However, strong Auger non-radiative recombination, while enabling photon antibunching in single QDs, also causes fluorescence blinking when QDs become charged. This poses a significant challenge in achieving both blinking-free emission and high-purity single-photon emission. Here, we address this issue with highly bright near-infrared (NIR) emitting InAs/InP/ZnSe/ZnS QDs, where the ZnSe layer acts as a confining layer to create a straddling band alignment. Single-QD measurements reveal that QDs with a thin ZnSe shell exhibit frequent Auger-related blinking. In contrast, increasing the thickness of the ZnSe shell reduces photo-charging by isolating excitons from the surface, significantly suppressing blinking. Importantly, these thick-shell QDs maintain high single-photon purity, with a g(2)(0) value below 1%. This results from strong exciton confinement in the cores, confirmed by an ultrafast biexciton Auger decay rate. These findings offer a solution to achieve non-blinking characteristics without compromising single-photon purity, highlighting the potential of InAs-based QDs as efficient quantum light sources for telecommunication applications.