Synthesis and Size-Dependent Optical Properties of Cd₃P₂ and (Cd_<i>x</i>Zn_1–<i>x</i>)₃P₂ Quantum Dots

Short-wave infrared (SWIR) materials are highly beneficial in telecommunications and medical imaging. Synthesis of quality SWIR chromophores remains challenging. Furthermore, many SWIR-emitting colloidal quantum dots (QDs) suffer from long radiative lifetimes and weak emission efficiencies. To address these challenges, we present methods to create a size series of Cd₃P₂ QDs and create a sizing curve. The results demonstrate that the growth kinetics and the production of Cd₃P₂ QDs with optical emission at 1.5+ μm are limited by the precursor stoichiometry. To address the overly long radiative lifetimes, we develop surface passivation with CdI₂ and develop a one-pot, hot-injection synthesis of (Cd_<i>x</i>Zn_1-<i>x</i>)₃P₂ QDs, which is shown to accelerate the PL dynamics of Cd₃P₂ QDs. Electron microscopy and elemental analysis point to the Cd₃P₂/(Cd_<i>x</i>Zn_1-<i>x</i>)₃P₂ core/crust structure of these QDs. These results show promise for the further development of core/shell Cd₃P₂/Zn₃P₂ QDs, which will serve as on-demand single-photon emitters in the SWIR region.