Synthesis and Size-Dependent Optical Properties of Cd<sub>3</sub>P<sub>2</sub> and (Cd<sub><i>x</i></sub>Zn<sub>1-<i>x</i></sub>)<sub>3</sub>P<sub>2</sub> Quantum Dots.

Smith, Logan; Halim, Abdul; Harbison, K Elena; Sapkota, Bibash; Klie, Robert; Diroll, Benjamin T; Fedin, Igor · Nano Lett · 2025

basic_science · Level V

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Abstract

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 Cd<sub>3</sub>P<sub>2</sub> QDs and create a sizing curve. The results demonstrate that the growth kinetics and the production of Cd<sub>3</sub>P<sub>2</sub> 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 CdI<sub>2</sub> and develop a one-pot, hot-injection synthesis of (Cd<sub><i>x</i></sub>Zn<sub>1-<i>x</i></sub>)<sub>3</sub>P<sub>2</sub> QDs, which is shown to accelerate the PL dynamics of Cd<sub>3</sub>P<sub>2</sub> QDs. Electron microscopy and elemental analysis point to the Cd<sub>3</sub>P<sub>2</sub>/(Cd<sub><i>x</i></sub>Zn<sub>1-<i>x</i></sub>)<sub>3</sub>P<sub>2</sub> core/crust structure of these QDs. These results show promise for the further development of core/shell Cd<sub>3</sub>P<sub>2</sub>/Zn<sub>3</sub>P<sub>2</sub> QDs, which will serve as on-demand single-photon emitters in the SWIR region.