Room-Temperature Quantum Emission from Cu<sub>Zn</sub>-V<sub>S</sub> Defects in ZnS:Cu Colloidal Nanocrystals.

Panfil, Yossef E; Thompson, Sarah M; Chen, Gary; Ng, Jonah J; Kagan, Cherie R; Bassett, Lee C · ACS Nano · 2025

basic_science · Level V

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Abstract

We report room-temperature observations of Cu<sub>Zn</sub>-V<sub>S</sub> quantum emitters in individual ZnS:Cu nanocrystals (NCs). Using time-gated imaging, we isolate the distinct ∼3-μs-long, red photoluminescence (PL) emission of Cu<sub>Zn</sub>-V<sub>S</sub> defects, enabling their precise identification and statistical characterization. The emitters exhibit distinct blinking and photon antibunching, consistent with individual NCs containing two to four Cu<sub>Zn</sub>-V<sub>S</sub> defects. The quantum emitters' PL spectra show a pronounced blue shift compared to NC dispersions, likely due to photochemical and charging effects. Emission polarization measurements of quantum emitters are consistent with a σ-character optical dipole transition and the symmetry of the Cu<sub>Zn</sub>-V<sub>S</sub> defect. These observations motivate further investigation of Cu<sub>Zn</sub>-V<sub>S</sub> defects in ZnS NCs for use in quantum technologies.