Using shape to turn off blinking for two-colour multiexciton emission in CdSe/CdS tetrapods

Abstract

Semiconductor nanostructures capable of emitting from two excited states and thereby of producing two photoluminescence colours are of fundamental and potential technological significance. In this limited class of nanocrystals, CdSe/CdS core/arm tetrapods exhibit the unusual trait of two-colour (red and green) multiexcitonic emission, with green emission from the CdS arms emerging only at high excitation fluences. Here we show that by synthetic shape-tuning, both this multi-colour emission process, and blinking and photobleaching behaviours of single tetrapods can be controlled. Specifically, we find that the properties of dual emission and single-nanostructure photostability depend on different structural parameters—arm length and arm diameter, respectively—but that both properties can be realized in the same nanostructure. Furthermore, based on results of correlated photoluminescence and transient absorption measurements, we conclude that hole-trap filling in the arms and partial state-filling in the core are necessary preconditions for the observation of multiexciton multi-colour emission.

Inverse-designed semiconductor nanocatalysts for targeted CO2 reduction in water

“…There has been some debate regarding which geometrical feature, arm length 51 or TP volume, 52 most affects the TP properties. Our results clearly show that both the excitonic structure and the optical properties are determined by the TP volume, more than by the arm length alone.…”

Amine‐Free Synthesis of Colloidal Cesium Lead Halide Perovskite Nanocrystals

“…Because of their strong steric effect, branched capping ligands are usually more preferred for improving the stability of NCs. The phosphine‐based capping ligands, such as trioctylphosphine oxide (TOPO), trioctylphosphine (TOP), and phosphonic acids have been widely used in the synthesis of conventional II–VI semiconductor crystals [42–48] . Because of the highly branched structure and relatively strong coordination ability, the phosphine‐based surface capping groups have been utilized by several research groups to make highly stable PNCs [24,34,39,41,49] …”

Quantum Dots Microstructural Metrology: From Time‐Resolved Spectroscopy to Spatially Resolved Electron Microscopy

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